Current research
Project Proposal
Summary
Objectives and Strategy
Potential Impacts and Major Products
Bibliography
Work plan
Task 1: Project Coordination
Task 2: Santa Clara Valley (Silicon Valley) 3D map
Task 3: Santa Rosa-Healdsburg Corridor geologic map
Task 4: Develop quantitative techniques
Task 5: Release of 3-D Geologic Maps
Task 6: Salinas Valley Neogene basin
analysis
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Three-Dimensional Geologic
Maps and Visualization
Project Proposal FY2002
Traditional
geologic maps that show structures and materials at the Earth's surface
no longer are sufficient for storing, displaying, and transmitting geoscience
information. Fully 3-dimensional geologic maps are needed to provide users
with geologic information of the quality, accuracy, and detail necessary
to solve problems related to natural hazard mitigation, resource management,
mineral and petroleum exploration, contaminant dispersion, and other issues.
The goal of this project is to produce 3-D geologic maps, including developing
the techniques needed to produce 3-D maps that retain all the detail in
traditional maps while extending this information into the subsurface.
Computer-based
representations of areal geology extended into the subsurface as 3-dimensional
geologic maps can now be developed to provide continuous quantitative
3-D geologic information for a variety of practical needs. Such 3-D databases
will allow even the inexperienced user to figuratively 'walk around' in
the Earth to examine the data and extract needed information. One important
application unique to 3-D geologic maps is predictive process modeling
of geologic, tectonic, and hydrologic processes needed for land-use planning,
hazard mitigation, and resource management. Examples of immediate applications
of 3-D maps include ground shaking estimation, refined earthquake relocation,
fault segmentation analysis for probabilistic earthquake forecasting,
resource exploration, contaminant source and dispersion pathway definition,
ground water flow modeling for resource management, and landslide modeling.
Traditional
geologic maps, which show the distribution and orientation of geologic
structures and materials at the ground surface, for decades have served
as effective tools for storing and transmitting geologic information.
The introduction of Geographic Information Systems enhanced traditional
geologic maps in terms of ease of use and communication of surface geologic
information. However, these maps, even enhanced with GIS capabilities,
are no longer sufficient for storing and transmitting subsurface information,
information that is critical in the role of the map as a window into the
subsurface. Fortunately, advances in computer hardware and geologic modeling
and visualization software now provide us the opportunity to construct
3-D geologic maps that retain all the information in a traditional geologic
map while explicitly and quantitatively extending this information throughout
the subsurface. The USGS is a world leader in the production of traditional
geologic maps, and now the time is right for us to move to the next level
by explicitly adding the third dimension.
The GOAL
of the project is to produce, display, and release quantitative 3-dimensional
geologic maps, initially of the San Francisco Bay region. The 3-D maps
will include, in a continuous quantitative volumetric format, the information
contained in traditional 2-D geologic maps and thus can form the bases
for predictive process modeling as well as address, in 3-dimensions, traditional
geologic map-based questions. A critical component of these 3-D maps will
be the explicit inclusion of continuous representations of uncertainties,
a topic not well handled even in traditional geologic maps. Fundamental
techniques peculiar to 3-D map generation will be developed to accomplish
this goal.
The STRATEGY
for accomplishing this goal is based on results of an earlier Venture
Capital Project (3-Dimensional Geologic Maps, Howell and Jachens, 1997),
ongoing experience in constructing a 3-D seismic velocity model for the
greater San Francisco Bay region (Jachens, NEHRP), and extensive work
by the GUMP group and WRD in building 3-D hydrogeologic models of basins.
These earlier efforts not only provide a valuable foundation on which
to build this project, but also highlight a number of technical problems
related to 3-D map building that need to be addressed and many techniques
that need to be developed.
The strategy is laid out below as a series of tasks,
with task 2 being both the overarching task of the project and also the integrator of subsequent subtasks. The list
of tasks represents our current understanding of what will be required to fully accomplish the goals of this project
in the broadest sense, but realistically others will appear as the work progresses and not all can be addressed at
the same time.
The major products from this project fall in 3 main categories:
1. traditional geologic maps and digital databases of the greater San Francisco Bay region and its expanding suburban
fringe; 2. initially a 3-D geologic map of the Santa Clara (Silicon Valley) and surrounding hillsides and, later,
equivalent maps of other parts of the San Francisco Bay region and other areas of California (actually 3-D geologic
models composed of 3-D digital databases linked and integrated by geologic concepts and rules); and 3. a philosophy,
framework, and set of new tools with which to construct, portray, and distribute 3-D geologic map information.
The traditional
geologic maps and digital databases will cover eastern Sonoma and western
Napa Counties, eastern Napa and Solano Counties, and parts of Lake, Mendocino,
and Colusa Counties. Geologic map coverages include the Sacramento and
Healdsburg 30' X 60' quadrangle, 1:24,000 scale quadrangles traversed
by active faults near Santa Rosa, and 1:24,000 scale quadrangles of the
northern Salinas valley. These maps represent completion of ongoing map
database efforts of the former San Francisco Bay Region Project, provide
basic geologic data in areas of rapid development, and address earthquake
hazard issues and provide slip rates important for forecasting future
earthquakes.
The Santa
Clara Valley 3-D geologic map and similar maps elsewhere in the state
will serve as foundations for process modeling on which to base decisions
related to earthquake hazards mitigation, ground water resource management,
and toxic contaminant dispersion. Immediate use of this map will be as
the basis for ground shaking estimation and ground water flow modeling.
The 3-D geologic maps are intended to be 'living' entities in the sense
that they will exist as digital databases linked and integrated by geologic
relationships, and will be designed for continual upgrading as new data
become available.
A successful
philosophy, framework, and set of tools for constructing 3-D geologic
maps with uncertainties should have wide ranging impact within the USGS
and throughout the geoscience community. The need for spatially referenced
geologic information is more critical than ever, but the traditional 2-D
geologic map no longer is sufficient for storing and transmitting spatially-referenced
3-dimensional geoscience information. The 3-D geologic map should find
wide-ranging application by both expert and non-expert alike.
Stanley,
R.G., and Lillis, P. G., 2000, Oil-bearing rocks of Davenport and Pt.
Reyes and offset along the San Gregorio and northern San Andreas faults
[abs.], Stanford University, Stanford, Calif., 3rd Conference on Tectonic
Problems of the San Andreas Fault System Program and Abstracts, September,
2000, unpaginated
Stanley,
R.G., and Lillis, P. G., 2000, Oil-bearing rocks of the Davenport and
Point Reyes areas and their implications for offset along the San Gregorio
and northern San Andreas faults, in Bokelmann, Götz, and Kovach,
R.L., eds., Proceedings of the 3rd Conference on Tectonic Problems of
the San Andreas Fault System: Stanford, Calif., Stanford University Publication
Geological Sciences, v. 21, p. 371-384
Powell, C.L.,
II, 2000, Age and paleoenvironment suggested by mollusks from the Purisima
Formation and related rocks (late Miocene and Pliocene), San Francisco
Bay area, central California, Western Society of Malacologists, Annual
Report, v. 32, p. 20-22
McLaughlin,
R.J., Sarna-Wojcicki, A., Fleck, R.J., Jachens, R.C., Graymer, R.W., Walker,
J.P., Valin, Z.C., and Nilsen, T.H, 2000, Evolution of the San Francisco
Bay structural block and northeastward migration of the San Andreas fault
system, Proceedings, 3d Conference on Tectonic Problems of the San Andreas
Fault System, Bokelmann, G., and Kovach, R. L., eds, Stanford University
Publication, Geological Sciences v.21, p. 370.
Stanley,
R.G., and Lillis, P. G., 2001, Tectonic disruption of a Miocene petroleum
system in coastal California [abs.], Geological Society of America Abstracts
with Programs, v. 33, no. 3, p. A-82.
Fitzgibbon,
T.T., Phelps, G.A., and Jachens, R.C, 2001, GIS tools for the construction
of 3D geologic models, Geological Society of America 2001 Abstracts with
Programs v. 33, p. A-40.
Jachens,
R.C., Wentworth, C.M., McLaughlin, R.J., Fitzgibbon, T.T., Phelps, G.A.,
Langenheim, V.E., Graymer, R.W., and Stanley, R.G., 2001, 3-dimensional
geologic map of the Santa Clara ("Silicon") Valley, California, : Geological
Society of America 2001 Abstracts with Programs v. 33, p. A-39.
Powell, C.L.,
II, and Allen, James, 2001, Invertebrate fossils from the Wilson Grove
Formation (late Miocene - late Pliocene), Sonoma County, northern California.,
Abstracts, North American Paleontological Convention 2001
Powell, C.L.,
II, 2001, Paleontological notes on Tertiary rocks in the Spreckles 15'
quadrangle, Monterey County, California. With description of an unusual
faunule from the Monterey Formation and a new Lucinid bivalve from the
Santa Margarita Formation
Task Leaders:
Jachens, Robert C.
jachens@usgs.gov
345 Middlefield Rd
Menlo Park, CA 94025
Phone: (650)329-5300
FAX: (650)329-5133
Task Text
Status: PROPOSED
Task priority: 1
Task Summary and Objectives:
Task 1 encompasses
project leadership activities such as project design, scheduling, and
sequencing, coordination of the activities of various project personnel
under tasks 2-6, insuring communication amongst project personnel and
between personnel and their clients and collaborators outside of the project,
maintenance of links to related GD and other USGS projects, allocation
of resources, preparation of project reports and continuing proposals,
responses to requests for information, acquisition of reimbursable funds
to enhance project activities, and other project janitorial functions.
These activities will continue throughout the life of the project.
Work to be undertaken during
the proposal year and a description of the methods and procedures
Work under
this task includes standard Project Chief activities such as preparing
for and attending project reviews, preparing continuing proposals, responding
to inquiries and requests from internal and external customers and clients,
monitoring progress of project participants, redirecting activities when
they stray from project goals, holding project meetings to promote communication,
putting out fires, orchestrating general project outreach activities,
etc. Specific activities will include: 1. forming a steering committee
from project participants, 2. investigating feasibility of a special project-related
set of papers/posters at regional GSA/AGU meeting, 3. developing a project
fact sheet, 4. developing a project web-site, and 5. developing 'stories'
for the National Atlas.
Planned Outreach
This project
retains the geologic mapping core of the former San Francisco Bay mapping
project, a project that developed a strong community base of support that
includes city and county geologists, engineers, and planners, other government
agencies - most particularly the National Park Service, as well as the
general public. Members of the project are regularly requested to address
specific questions or to provide general information regarding regional
relations. Most of these inquiries stemmed from the traditional 2-D surface
mapping, and we anticipate that these requests will continue and that
we will respond to them.
As we enter
the 3-D phase of producing maps of the San Francisco Bay region, many
new uses of the expanded geologic information will be possible and many
new derivative products can be produced. These new uses and products,
however, will not be familiar to our normal customers, and so an extensive
outreach effort will be needed both to inform potential customers of the
capabilities and utility of 3-D geology and to solicit their input concerning
the needs they have for 3-D geology, the types of derivative products
that would be most useful, and what elements, properties, and characteristics
they would like to see included in the 3-D geologic maps.
Publications planned for this
task, to be submitted for publication in current or future fiscal years.
Howell, D.G.,
Jachens, R.C., and others, 2001, Mapping the Santa Clara Valley, California,
in 3-Dimensions
Jachens,
R.C., Wentworth, C.M., Gautier, D.L., and Pack, S., 2001, 3D geologic
maps and visualization: a new approach to the geology of the Santa Clara
('Silicon') Valley, California, in Soller, D.R., (ed.), Proceedings, Digital
Mapping Techniques 2001 workshop
Geographic area of task:
United States,
Western US, CA
ACCOMPLISHMENTS
Current year
nonpublication accomplishments and outcomes:
* Built a
preliminary project website, describing goals, plans, and strategies for
accomplishing the project goals. This website continues under development.
(URL XXX)
* Built an
easily accessible internal website for rapid, convenient exchange and
comparison of data and ideas related to constructing the 3D geologic map
of the Santa Clara Valley.
* Applied
for, and was granted authorization to recruit candidates for a USGS Mendenhall
Post Doctoral Fellowship to investigate and develop a model for the sedimentary
architecture of the Plio-Quaternary deposits of the Santa Clara Valley.
* Coordinated
project activities with internal USGS and external projects including:
1) Geologic Division's Southern California Areal Mapping Project and Hydrogeologic
Framework of Aquifer Systems in the Desert Southwestern United States
Project, 2) Water Resource Division's 29 Palms MAGCC, San Bernardino/Rialto-Colton
basin, and Santa Clara Valley cooperative ground water investigations,
and 3) joint USGS/Stanford Project-The San Andreas Fault Observatory at
Depth, a project to drill and instrument a deep site in the seismogenic
part of the San Andreas fault near Parkfield, California.
* Provided
baseline geologic and geophysical information and interpretations for
Bay bridge retrofit (J. Hamilton), Richmond-San Rafael bridge retrofit
(AMEC Earth and Environmental), Santa Clara County Geologist (J. Baker),
City of Los Gatos (J. Nolan and Assoc.), Lexington Reservoir mitigation,
Santa Clara Valley Water District (R. Volpe and P. Frame), California
Div. Mines and Geol. (K. Knudsen), Mid-Peninsula Open Space District (M.
Freeman), and consulting geologist (J. Woodruff), Cal State U. Hayward
fault study (Lettis and Associates), Bay Nature Magazine, Pescadero Watershed
Advisory Comm., Hazard Zonation, San Jose and San Francisco (CDMG)
* Numerous
internal and external lectures, demonstrations, and advisory meetings
describing the project and its goals (see next section)
Highlights-
summary of the most significant outcome:
The most
significant outcome that has resulted from project management activities
is the high degree of visibility and interest in the 3D Geologic Maps
and Visualization Project already evident even though the project is only
8 months old. I and other project members have spent significant amounts
of time responding to requests for lectures, briefings, demonstrations,
and consultation both within and outside of the USGS, including:
Presentations
to external entities
* San Francisco
Bay region municipal water districts, users, and interested parties
* Digital
Mapping Techniques 2001 Workshop (at request of representative from California
Division of Mines and Geology)
* Incorporated
Research Institutes for Seismology executive committee representatives
* Congressional
staffer for local Representative
Presentations
to USGS entities
* Water Resources
Future Science Directions workshop
* National
Earthquake Hazards Reduction Program future science directions planning
committee: recommendations on need for traditional geologic maps, 3D geologic
maps, 3D models to support future process modeling
* Internal
workshop for science planning, EarthScope/USArray
* Water Resources
western states District representatives
* Water Resources/Geologic
Division ad hoc group for coordination of activities in arid southwestern
United States
* Southern
California Areal Mapping Project review
* San Andreas
Fault Observatory at Depth review
Task 2: Construct a 3-dimensional geologic map of
the Santa Clara Valley (Silicon Valley), California, and surrounding hillsides
Task Leaders:
Jachens, Robert C.
jachens@usgs.gov
345 Middlefield Rd
Menlo Park, CA 94025
Phone: (650)329-5300
FAX: (650)329-5133
Task Text
Status: PROPOSED
Task priority: 1
Task Summary and Objectives:
This task
is the heart of the project. The 'ideal target' map will define a volume
of the crust in which the geologic units, contacts, rock types, faults,
folds, other structures, physical properties (seismic velocity and attenuation,
density, magnetic susceptibility, porosity, permeability, etc.), earthquake
hypocenters, and other quantities or parameters will be defined everywhere.
In addition, uncertainties associated with these elements, quantities,
and parameters will be included. It also will serve as a 3-D spatially-reference
archive for the geological data and reasoning that form the foundation
of the map. This obviously is an enormous task that will extend over many
years, but we plan to release interim 3-D maps that satisfy subsets of
the conditions described above, subsets that will satisfy specific modeling
needs related to earthquake, groundwater, and contamination issues.
The study
area has a number of advantages, both in terms of important problems whose
solution will be enhanced with a 3-D geologic map, and in terms of the
means needed to construct the 3-D map. Problems that will benefit from
a 3-D geologic map include: 1. prediction of ground shaking from local
earthquakes (an extremely important issue to Silicon Valley industries
and the infrastructures that support them); 2. analysis of stress accumulation
and interaction in 3-D on active faults, needed to better forecast the
location and magnitude of future earthquakes; 3. accurate location of
earthquake hypocenters; 4. ground water management and contaminant dispersion;
5. natural source contamination by Hg and asbestos. Map construction advantages
include: 1. some initial work already done under NEHRP; 2. geologists
who mapped and/or compiled geology are on project; 3. area is THE 'type'
basin selected by NEHRP for shaking modeling; 4. area is target of new
ground water flow model project-coop with GD, WRD, and Santa Clara Valley
Water District (4 yr funding just approved)
Work to be undertaken during
the proposal year and a description of the methods and procedures:
The fundamental
architecture of the 3D geologic map of Santa Clara Valley has been defined
(see Highlights) and consists of 11 major faults and the following geologic
units (with associated properties and uncertainties): 1. a Mesozoic subduction-related
basement made up of accreted terranes of Franciscan Complex rocks, Coast
Range ophiolite, and forearc sedimentary sequences; 2. Mesozoic granitic
and metamorphic basement SW of the San Andreas fault; 3. older Tertiary
strata that fill 2 deep basins along the valley edges and the La Honda
basin SW of the SAF; 4. Plio-Quaternary non-marine deposits; and 5. Holocene
deposits. Efforts this past year have provided the experience base that
allows us to define 1) the critical elements needed for the 3D map, and
2) the roadmap we should follow in quantifying them.
During this
proposal year, we will focus on producing quantitative 3D representations
of the most important surfaces and their associated uncertainties, and
on understanding the sedimentary architecture of concealed units.
Subtask 2a. Map the Loma Prieta, Hayward, Calaveras,
Monte Vista, and Monte Vista Basin Faults in 3-D. Gravity, magnetic, and surface geologic map data will be integrated
with seismicity, sparse well data, results of a new seismic reflection/refraction profile, seismicity, and deformation
modeling results to map the 3-D shape, location, and attitude of the faults. Hydrologic data and aeromagnetic data
will be interpreted to define faults cutting the basin fill.
Subtask
2b. Analyze Older Tertiary Section within Cupertino Basin. Existing
data on the Miocene and older deposits within the Santa Clara Valley have
been synthesized and interpreted. New mapping planned for the Tertiary
strata at Blossom Hill, will be integrated with results from the coincident
seismic reflection/refraction and gravity profiles and other geophysical
data to unravel the distribution, age, and internal and bounding structures
of the deeper parts of the Cupertino basin.
Subtask
2c. Define Concealed Top of Franciscan Basement. New gravity data
and a refined procedure for inverting gravity data to define the thickness
of Cenozoic deposits (see Subtask 4c) will be used to recalculate the
depth to Franciscan basement rocks concealed beneath the Santa Clara Valley,
and to systematically assess the likely uncertainties associated with
this constrained inversion of the gravity data.
Subtask
2d. Evaluate the Silver Creek fault and Evergreen Basin. Geologic
mapping and potential field geophysical analysis will focus on resolving
discrepancies between two disparate models for the relationship and nature
of the Silver Creek fault relative to the Evergreen basin..
Subtask
2e. Analyze the Shape, Age, and Internal Architecture of the Plio-Quaternary
Section. Work will continue in close cooperation with San Jose State
University and the WRD/Earthquake Hazards/Santa Clara Valley Water District
cooperative project to analyze well data, outcrop information, and geophysical
logs to define the lithology, structure, and sedimentary architecture
of the Plio-Quaternary Santa Clara Gravels and their counterparts buried
beneath the valley. Paleomagnetic studies of cores will provide age data
on the upper 300 m of basin fill.
Subtask
2f. Map 3D Shape and Location of Concealed Ophiolites. This year,
we will begin to apply the magnetic inversion technique developed under
subtask 4b to quantitatively define ophiolitic bodies beneath Santa Clara
Valley. These bodies are important geologic elements, potential sources
of natural contamination by asbestos and Hg, and tend to lie along major
ancient faults that cut the Mesozoic basement. SW of the San Andreas fault,
an enormous concealed body of ophiolitic (Logan) gabbro is a major structural
element in the basement, and an important control on seismic wave propagation.
Planned Outreach:
Planned outreach
under this task initially will be focussed on the process modelling community
who will be the primary users of the initial model. These will include
seismic wave propogation modelers who are estimating ground shaking, relocating
earthquakes, studying earthquake source parameters, and investigating
seismic wave focussing, tectonic modelers who are studying fault block
interactions on the Hayward and Calaveras faults to understand fault creep,
stress interactions, and 3-D stress accumulation in relation to earthquakes
on the Hayward fault, and ground water hydrologists who are building a
refined ground water flow model of the Santa Clara Valley. Contacts will
be maintained to insure that the 3-D geologic map contains the critical
information needed for the specific process models. Personal information
feedback loops will be established with 3-D map users so that the results
of process modelling can be used to guide modifications of the 3-D map,
assess the validity of assigned uncertainties, and correct any errors.
Special attention will be paid to maintaining these feedback loops because
this type of interaction between map producer and map user is not the
norm. The importance of these feedback loops on the quality and accuracy
of the final 3-D geologic maps cannot be overestimated.
Publications delivered/completed
for this Task:
Stanley,
R.G., and Lillis, P. G., 2000, Oil-bearing rocks of Davenport and Pt.
Reyes and offset along the San Gregorio and northern San Andreas faults
[abs.], Stanford University, Stanford, Calif., 3rd Conference on Tectonic
Problems of the San Andreas Fault System Program and Abstracts, September,
2000, unpaginated
Stanley,
R.G., and Lillis, P. G., 2000, Oil-bearing rocks of the Davenport and
Point Reyes areas and their implications for offset along the San Gregorio
and northern San Andreas faults, in Bokelmann, Götz, and Kovach,
R.L., eds., Proceedings of the 3rd Conference on Tectonic Problems of
the San Andreas Fault System: Stanford, Calif., Stanford University Publication
Geological Sciences, v. 21, p. 371-384
Stanley,
R.G., and Lillis, P. G., 2001, Tectonic disruption of a Miocene petroleum
system in coastal California [abs.], Geological Society of America Abstracts
with Programs, v. 33, no. 3, p. A-82.
Jachens,
R.C., Wentworth, C.M., McLaughlin, R.J., Fitzgibbon, T.T., Phelps, G.A.,
Langenheim, V.E., Graymer, R.W., and Stanley, R.G., 2001, 3-dimensional
geologic map of the Santa Clara ("Silicon") Valley, California, : Geological
Society of America 2001 Abstracts with Programs v. 33, p. A-39.
Publications planned for this task, to be submitted for publication in
current or future fiscal years.
Stanley,
R.G., Jachens, R.C., Lillis, P.G., McLaughlin, R.J., Kvenvolden, K.A.,
Hostettler, F.D., McDougall, K.A., and Magoon, L.B., 2001, Subsurface
and petroleum geology of the southwestern Santa Clara Valley ("Silicon
Valley"), California, U.S. Geological survey Professional Paper
Mankinen,
E.A., 2001, Preliminary paleomagnetic results from the Coyote Creek Outdoor
Classroom drill hole, Santa Clara valley, California , U.S. Geological
Survey Open-File Report 01-XXX
McLaughlin,
R.J., Clark, J.C., Brabb, E.E., Helley, E.J., and Colon, C.J., , 2001,
Geologic maps and structure sections of the southwestern Santa Clara Valley,
and southern Santa Cruz Mountains, Santa Clara and Santa Cruz Counties,
California, U.S. Geological Survey Miscellaneous Field Investigation Report
MF-____ , spatial database, digital web publication, Print on Demand format,
5 map sheets, 2 sheets of structure sections, explanation and figures,
interpretive text pamphlet and separate database pamphlet
Wentworth,
C.M., Hansen, R.T., and others, 2001, Preliminary description of cores,
logs, and cuttings from the Coyote Creek Outdoor Classroom and Willow
drill holes, Santa Clara Valley, California, U.S. Geological Survey Open
File Report 01-XXX
Roberts,
C.W., Jachens, R.C., Langenheim, V.E., and others, 2002, Isostatic residual
gravity map of the Santa Clara Valley and vicinity, California
Jachens,
R.C., Langenheim, V.E., and others, 2002, Aeromagnetic map of the Santa
Clara Valley and vicinity, California
Geographic area of task:
United States,
Pacific Coastal States, CA
Polygon Lat/Long:
-122.223 37.3189, -121.899 37.0668, -121.626 37.3629, -121.918 37.6097
ACCOMPLISHMENTS
Current year nonpublication
accomplishments and outcomes:
Progress
has been made on many aspects of constructing a 3D geologic map of the
Santa Clara Valley, and the 8 months since the inception of the project
have permitted us to begin many efforts, most of which will require more
time to complete. To date, we have
* Contracted
a new high-definition aeromagnetic survey to complete modern coverage
of the valley.
* Compiled
best digital position data for bedrock traces of the Hayward, Calaveras,
San Andreas, Pilarcitos, Berrocal, and Monte Vista faults
* Defined
preliminary 3D surfaces of the Hayward, Calaveras, and Loma Prieta faults,
and an un-named fault beneath the Cupertino basin, based on a new high-resolution
catalogue of earthquakes relocated by the double-difference technique,
and compared these surfaces to mapped fault traces.
* Began reexamining
hydrologic evidence for faults cutting alluvium in Cupertino basin.
* Began multi-pronged
effort to refine the critical surface defining the base of the Tertiary
rocks. Detailed gravity was collected along the new seismic reflection/refraction
line along Los Gatos Creek and a new gravity survey of the Cupertino basin
was launched to define possible thrust-related structures at the bottom
of the basin. The new gravity work coupled with basin-depth constraints
from the seismic profile and new, carefully logged wells (one of which
bottomed in serpentinite) provide the basis for a significant refinement
of the 3D preTertiary basement surface.
* Began gravity
and geologic investigation to define local (pull-apart?) basin along Calaveras
fault.
* In cooperation
with Earthquake Hazards team, WRD, and Santa Clara Valley Water District,
determined that the upper sections (810 and 1011 ft) in 2 new wells are
entirely alluvial and probably were deposited within the past 0.5 Ma.
* Examined
driller's logs of Holocene section throughout valley with regard to distribution
of sand and gravel in 3D. No clear spatial pattern is evident.
Highlights- summary of the
most significant outcome:
Our major accomplishment is the definition of the fundamental
architecture of the Santa Clara Valley 3D map, and the construction of a 'strawman' map populated with approximate
surrogates of the surfaces that will make up the final map (see current research). The map
exists in the computer as a set of digital grids that define the critical geologic surfaces in 3D, and a set of instructions
in earthVision® that specify how the surfaces interact when they encounter each other (i.e. which surfaces truncate
against which). This digital map is represented in the flow diagram (see the 'real' 3D map),
and the block diagrams (see current research) can be thought of as cartographic representations
of the digital map. The map volume is divided into fault blocks by 11 major faults, and each fault block includes
up to five major geologic units that will be subdivided to accommodate geologic complexity.
The present
3D map is in a wonderfully flexible format that permits progressive systematic
refinement of the map without disrupting its fundamental architecture.
It also permits the addressing of scientific issues with available 3D
map information without having to wait for the final map. The progressive
refinement takes place surface by surface. Whenever a specific geologic
surface (e.g. the San Andreas fault) is defined to our satisfaction, we
simply replace the surrogate digital grid in the computer with our new
grid, activate the geologic-structure-building software, and, thus, produce
a refined version of the 3D geologic map. Individual fault blocks or geologic
units can be subdivided by additional faults and/or contacts simply by
adding digital surfaces and interaction instructions, and again activating
the geologic-structure-building software. We currently are focussing on
refining surfaces defining the active faults, and the bases of the Holocene
and Tertiary deposits.
New Directions or Major Changes
for Proposal Year:
The project
and this task will continue in the direction outlined in the initial proposal.
Because the Santa Clara Valley 3D geologic map is solidly on course, and
because many of the 'startup' problems for a 3D geologic map have been
successfully addressed, we propose to begin a modest effort constructing
a 3D geologic map of the San Bernardino basin and vicinity in southern
California. This basin straddles the highly active San Jacinto fault and
is thus subject to potentially devastating shaking from local earthquakes
on the San Jacinto and San Andreas faults. Also, the basin has critical
ground water issues related to contamination, water banking, and resource
usage. Therefore, a 3D geologic map is needed on which to base estimates
of ground shaking and on which to design a new ground water flow model.
OneD and 2D maps are not adequate. We will work closely with members of
the Southern California Areal Mapping Project and with the San Diego Project
Office of WRD to construct this 3D geologic map.
Task 3: Santa Rosa-Healdsburg Corridor and North Bay
Geologic Mapping and Umbrella Activities
Task Leaders:
McLaughlin, Robert J
rjmcl@usgs.gov
345 Middlefield Rd
Menlo Park, CA 94025
Phone: (650)329-4945
FAX: (650)329-4936
Task Text
Status: PROPOSED
Task priority: 1
Task Summary and Objectives:
The new,
three dimensional model of geologic mapping will require ongoing mapping
of geologic materials and structures at the Earth's surface. In fact,
construction of 3D geologic maps will almost certainly require collecting
an expanded set of surface observations to enable accurate projection
into the subsurface. Furthermore, because human interaction with the Earth
happens primarily at the surface, accurate surface geologic map databases
are a valuable resource.
The goal
of this task is acquisition of modern geologic maps of the Santa Rosa-Healdsburg
corridor and adjacent areas of the northern San Francisco Bay region.
Geologic mapping here is critical both from the perspective of human/Earth
interaction and for understanding the structure and tectonic evolution
of the Pacific-North American strike-slip plate boundary. The area is
located at the suburban fringe expanding rapidly outward from the central
San Francisco Bay region and thus needs modern geologic maps for hazard
evaluation and land-use planning. Development is rapidly obscuring critical
geologic information, so postponing the mapping is not an option. The
area also straddles the Rodgers Creek-Healdsburg-Maacama fault system
which not only poses a significant potential hazard, but also is a key
element in understanding the San Andreas fault system and its evolution
with time. Modern geologic maps are needed to unravel the slip history
on these faults and to understand the right-stepping development of the
plate margin. This work ties directly with paleoseismologic and related
work being conducted by the National Earthquake Hazards Reduction Program.
Work to be undertaken during
the proposal year and a description of the methods and procedures:
The work outlined under this task extends that outlined
under Task 3 of the project work proposal for FY01. The new geologic map data are composed of previously published
and unpublished maps augmented with newly collected geologic information in critical areas. The new and compiled mapping
is integrated into geologic map databases in Arc/Info using standard methodology developed by the previous San Francisco
Bay Geologic Mapping Project. High quality digital geologic maps are produced from the databases via ArcPlot. FGDC
Metadata are produced to accompany each map database. Maps and map databases are published as MF series maps via the
Internet and USGS Map-on-Demand.
Subtask
3a. Continuation of new geologic mapping of the Santa Rosa, Mark West
Springs, Healdsburg, Jimtown, Geyserville, Mount St. Helena, Asti and
The Geysers 24k quadrangles, in conjunction with compilation of other
new mapping for the Healdsburg 30' X 60' quadrangle.
New mapping in the Santa Rosa 24k quadrangle will contribute to a compilation
of the Napa 30' X 60' quadrangle by the California Division of Mines and
Geology for use in their earthquake hazards zonation. Geologic maps of
the Jimtown and Mark West Springs 7.5'quadrangles, that include most of
the southern Maacama fault, will be completed in FY 01 and submitted to
western publications in FY02. The Geysers, Healdsburg and Santa Rosa 24k
quadrangles will be completed and submitted to team review in FY02
Subtask
3b The new 24k scale mapping under Subtask 3a will provide a stand-alone
geologic framework to complement an ongoing earthquake hazards investigation
by McLaughlin and Sarna-Wojcicki, of the active Rodgers Creek, Healdsburg,
and Maacama fault zones, which underlie the rapidly urbanizing Santa Rosa
area. The mapping focuses on the stratigraphy and structure of Miocene
to Holocene basins along active faults in the northern San Francisco Bay
area. Sedimentologic and geochronologic data are also collected during
the geologic mapping, for use in determining Pleistocene to Holocene slip
rates and segmentation characteristics of the strike-slip faults, and
rates of contractional deformation of well dated deformed datums. These
data also are used to assess the likelihood of active blind thrust faults
beneath the area. Data on paleoflow from late Tertiary and Quaternary
fluvial gravels is integrated with the distributions of geochemically
distinct obsidian clasts in the gravels . Amounts of strike-slip displacement
across the Rodgers Creek., Healdsburg and Maacama faults are then inferred
from estimates of displacement of the obsidian clasts from in-situ source
areas. Ar/Ar age dates and tephrachronology of the late Tertiary volcanic
rocks are used to independently constrain offset across the strike-slip
faults. Fossil data, where present, and other isotopic methods, including
radiocarbon, thermoluminesence and cosmogenic radionuclides, may be employed
where appropriate, to date the Pleistocene-Holocene deposits and the timing
of fault slip.
Subtask 3c In FY02 subsurface data assembled from
water and oil well logs from west of and surrounding Santa Rosa will be tabulated and entered into a 3D model, in
earthVision®, in conjunction with construction of structure sections across the map area.
The geology will be integrated with gravity and aeromagnetic data to model the thickness, configuration and depth
to the top of well dated Late Tertiary volcanic rock units, to constrain rates of shortening and uplift.
Subtask 3d Cooperation will continue with the Earthquake
Hazards Team (C. Prentice and D Schwartz) in providing geologic data for locating and evaluating potential sites for
trenching investigations on the Healdsburg segments of the Rodgers Creek fault and on the Maacama fault.
Planned Outreach:
* The project
web page, SFGEO, continues to be an easy conduit for public access to
our geologic maps and related efforts. New for 2000 are a clickable index
map, "what's new" updates, and revised graphics. http://sfgeo.wr.usgs.gov
* Involvement
will continue with FEMA Project Impact efforts. Berkeley is the current
Impact community, and linkage with that effort has been established. Geologic
map databases will be provided for hazard analysis efforts by USGS and
California Division of Mines and Geology collaborators.
* New 24k
geologic map databases will be provided for use in other earthquake hazard
studies by USGS (C.Prentice, D. Schwartz) and CDMG (D. Wagner, K. Knudsen)
collaborators.
* Discussions
with geothermal operators (Thomas Box, Calpine; and William Smith, Northern
California Power Agency) at The Geysers geothermal field will continue,
to explore availability of deep drill hole data.
* Some vineyard
operators (T. Spence, Jordan Vineyards) are interested in potential uses
of geologic map databases for integration of geology, soil distribution
and topography.
* Interaction
with Sonoma State U., (Dr. Terry Wright; Dr. Thomas Anderson) will continue.
Invited talks on the local geology are attended by students, faculty,
local geotechnical companies, retired oil and geothermal industry geologists
and some property owners. Wright is a USGS Volunteer for Science, contributing
to the geologic mapping.
* A major
cooperative effort with the CDMG (David Wagner, Keith Knudsen) was initiated
in FY 01, with the beginning (7/1/01) of a new project by the State to
produce upgraded 24k scale geologic maps for use in their earthquake hazards
zoning. Meetings with David Wagner resulted in informal agreements to
provide CDMG with our 24k scale geologic mapping in the Napa and Healdsburg
30' X 60' quadrangles. The CDMG will contribute support for geochronologic
and tephrachronologic work.
Publications delivered/completed
for this Task:
Powell, C.L.,
II, 2000, Age and paleoenvironment suggested by mollusks from the Purisima
Formation and related rocks (late Miocene and Pliocene), San Francisco
Bay area, central California, Western Society of Malacologists, Annual
Report, v. 32, p. 20-22
McLaughlin,
R.J., Sarna-Wojcicki, A., Fleck, R.J., Jachens, R.C., Graymer, R.W., Walker,
J.P., Valin, Z.C., and Nilsen, T.H, 2000, Evolution of the San Francisco
Bay structural block and northeastward migration of the San Andreas fault
system, Proceedings, 3d Conference on Tectonic Problems of the San Andreas
Fault System, Bokelmann, G., and Kovach, R. L., eds, Stanford University
Publication, Geological Sciences v.21, p. 370.
Powell, C.L.,
II, and Allen, James, 2001, Invertebrate fossils from the Wilson Grove
Formation (late Miocene - late Pliocene), Sonoma County, northern California.,
Abstracts, North American Paleontological Convention 2001
Powell, C.L.,
II, 2001, Paleontological notes on Tertiary rocks in the Spreckles 15'
quadrangle, Monterey County, California. With description of an unusual
faunule from the Monterey Formation and a new Lucinid bivalve from the
Santa Margarita Formation
Publications planned for this
task, to be submitted for publication in current or future fiscal years.
Graymer,
R.W., Jones, D.L., Brabb, E.E., Barnes, J., Stamski, R.E., and Nicholson,
R.S, 2001, Geologic map and map database of eastern Sonoma and western
Napa Counties, California, U.S. Geological Survey Miscellaneous Field
Studies MF-XXXX
Graymer,
R., Brabb, E., Jones, D., and others, 2002, Geologic map and map database
of the Sacramento 30'X60' quadrangle, California
Graymer,
R.W., Jones, D.L. and Brabb, E.E., 2001, Geologic map and map database
of Solano and eastern Napa Counties, California, U.S. Geological Survey
Miscellaneous Field Studies MF-XXXX
McLaughlin,
R.J., and others, 2002, Geology and structure sections of the Jimtown
1:24,000 quadrangle, Sonoma County, California
McLaughlin,
R.J., and others, 2002, Geology and structure sections of the Mark West
Springs 1:24,000 quadrangle, Sonoma County, California
Blake, M.C.,
Graymer, R.W., and Stamski, R.E, 2001, Geologic map and map database of
western Sonoma, northermost Marin, and southernmost Mendocino Counties,
California, U.S. Geological Survey Miscellaneous Field Studies MF-XXXX
Graymer,
R.W., Knudsen, K., and Mills, S., 2001, Geologic map and map database
of the Stockton 30'X60' quadrangle, California, Graymer, R.W., Knudsen,
K., and Mills, S
Graymer,
R.W., Sarna-Wojcicki, A.M., Walker, J.P., and McLaughlin, R.J., 2001,
Controls on timing and amount of right-lateral offset on the East Bay
Fault System, California
McLaughlin,
R.J., Sarna-Wojcicki, A.M., Fleck, R.J., Jachens, R.C., Graymer, R.W.,
Nilsen, T.H., Walker, J.P., and Valin, Z.C., 2002, Evolution of Pliocene-Quaternary
faulting at the northeast side of San Francisco Bay structural block:
its bearing on eastward migration of the Pacific-North American Plate
boundary
McLaughlin,
R.J., and others , 2003, Geologic map, structure sections and map database
for Healdsburg 7.5'quadrangle, Sonoma County, California, U.S. Geological
Survey Miscellaneous Field Studies Map MF-XXXX.
McLaughlin,
R.J., and others , 2003, Geologic map, structure sections and map database
for the Santa Rosa 7.5'quadrangle, Sonoma County, California, : U.S. Geological
Survey Miscellaneous Field Studies Map MF-XXXX.
McLaughlin,
R.J, 2003, Geologic map, structure sections and map database for The Geysers
7.5'quadrangle, Sonoma County, California, U.S. Geological Survey Miscellaneous
Field Studies Map MF-XXXX.
McLaughlin,
R.J., 2003, Geologic maps, structure sections and map databases for Asti,
Mount St. Helena and Calistoga 7.5' quadrangles, Sonoma County, C, U.S.
Geological Survey Miscellaneous Field Studies Map MF-XXXX.
McLaughlin,
R.J., 2005, Geologic map of the Healdsburg 30' X 60' quadrangle, California,
U.S. Geological Survey Miscellaneous Field Studies Map MF-XXXX.
Valin, Z.C.
and others, 2002, A Deep and shallow well database from oil and water
wells, for basins west of and surrounding Santa Rosa, California: a digital
database.
Graymer,
R.W., 2001, East Bay geology, including the Hayward fault, landslides,
and ancient volcanoes, National Association of Geology Teachers, Far West
Section Field Trip Guidebook to the San Francisco Bay Region
Geographic area of task:
United States,
Pacific Coastal States, CA
Polygon Lat/Long: 39/123, 39/122, 38 30/123, 38 30/122
United States,
Pacific Coastal States, CA
Polygon Lat/Long: 38 30/123, 38 30/122, 38/123, 38/122
United States,
Pacific Coastal States, CA
Polygon Lat/Long: 39/122, 39/121, 38 30/122, 38 30/121
ACCOMPLISHMENTS
Current year nonpublication accomplishments and outcomes:
* Field trip/Workshop
to address Earthquake Hazards and Crustal structure issues in the northern
San Francisco Bay region (6/19/01-6/20/01). A two day workshop organized
by the 3-D Geologic maps and Visualization project(WESP) jointly with
San Francisco Bay Region Earthquake Hazards Project (NEHP). Field trip
included geologic mappers, geophysicists, paleoseismologists, and seismologists
from Western Earth Surface Processes and Earthquake Hazards teams, the
California Division of Mines and Geology, the geotechnical community and
faculty and graduate students from San Francisco State and San Jose State
Universities. The workshop emphasized an integrated scientific approach
to understanding earthquake hazards and crustal structure in the northern
San Francisco Bay region.
* New cooperation
was initiated with California Division of Mines and Geology, with their
new earthquake hazards mapping work in the northern San Francisco Bay
region
* Digital
geologic map files for the Jimtown, Mark West Springs, Santa Rosa and
Healdsburg 7.5'quadrangles were established. Geologic mapping in Jimtown
and Mark West Springs quadrangles will be completed FY 01 and published
in FY02.
* A digital
database was begun of water and oil well locations.
* Undated
late Tertiary volcanic rocks in fault blocks respectively SW of the Healdsburg
fault, and SW and NE of the Maacama fault, were sampled for Ar/Ar dating.
Northwestward-and eastward younging age progressions in the volcanic rocks
in each fault block should allow us to separately constrain the amounts
of displacement across the Healdsburg-Rodgers Creek and Maacama faults.
Highlights- summary
of the most significant outcome:
Our estimate
of long term slip on the Maacama fault, based on the offset of obsidian
clast lithofacies in Plio-Pliestocene gravels since 2.5 MA yielded a rate
of 6.2+/- 1.0 mm/yr. For the Healdsburg-Rodgers Ck fault zone obsidian
clast lithofacies offset yielded a slip rate of 5.8+/- 1.8mm/yr since
2.5 MA. Aggregate slip across the Healdsburg-Rodgers Creek and Maacama
faults based on obsidian clast provenance is 12 +/- 0.9mm/yr. In 1992
a Holocene slip rate of 8 +/- 2 mm/yr since 750 YBP was determined by
D. Schwartz and others for the Rodgers Creek fault southeast of Santa
Rosa.
A separate
estimate of slip across the Maacama fault, based on the offset of 2.5-3.1
MA volcanic rocks, yields a maximum rate of 9.2+/- 0.9 mm/yr. Ar/Ar dating
underway will further constrain this rate.
Preliminary
SW-NE structure sections across the Healdsburg and Mark West Springs 7.5'
quadrangles, were constructed for estimating rates of late Pliocene and
younger contraction across the Healdsburg-Rodgers Creek and Maacama faults.
Preliminary results indicate shortening of 0.1-0.2 mm/yr between the Healdsburg
and Maacama faults since 3.1 MA.
New Directions or Major Changes
for Proposal Year:
A significant
FY01 effort under Task 3 was devoted to completing regional mapping and
compilation of regional geologic map databases to complete the preliminary
map database of the San Francisco Bay region, primarily in the north Bay.
This work largely will be completed this fiscal year. Therefore, some
of the resources devoted to Task 3 this year will be redirected next year
to geologic mapping over the expanding San Francisco Bay region suburban
fringe to the south, in the Salinas-Monterey area. These plans are detailed
in Task 6 of the present proposal.
Task 4: Develop New Quantitative Techniques for Producing
3-D Geologic Maps
Task Leader:
Jachens, Robert C.
jachens@usgs.gov
345 Middlefield Rd
Menlo Park, CA 94025
Phone: (650)329-5300
FAX: (650)329-5133
Task Text
Status: PROPOSED
Task priority: 1
Task Summary and Objectives:
Traditional
geologic maps contain explicit information about the subsurface in the
form of strikes, dips, fold axes, cross sections, fault traces and attitudes,
etc. and implicit information like distribution and apparent thickness
of units, and contacts on topography. This information generally is unevenly
distributed and not suited to creating a fully 3-D map. Quantitative techniques
for projecting surface geologic information into the subsurface need to
be developed.
Gravity and
magnetic surveys will cover most study areas, and these data contain direct
information about geology and structure in 3-D. 3-D methods are needed
for automatic depth estimation from potential field anomalies, compact
body determination, direct fault geometry determination, inversion with
explicit and 'fuzzy' constraints, ideal body theory, joint gravity and
magnetic inversion, and basin analysis.
Direct geologic
information about the subsurface (from well core, well logs, excavations,
seismic profiling, etc.) will be sparse for most areas. These data need
to apply throughout 3-D maps, but brute force interpolations by surface
fitting will seldom yield adequate results. 'Smart' procedures that interpolate
sparse data according to a priori geologic principles, remote geophysical
constraints, statistical representations of properties, self-educating
algorithms, or other methods are desperately needed.
For many
process modeling applications (e.g. ground water flow, reservoir response,
ground shaking estimation), geologic properties may often be represented
better statistically than deterministically. Even where deterministic
representations are preferable, often the data available will not permit
a sufficiently realistic deterministic representation. To satisfy these
cases, research is needed on methods to define the statistical distributions
of properties such as permeability, fracture density and orientation,
elastic properties, magnetic properties, and many others.
Work to be undertaken during
the proposal year and a description of the methods and procedures:
The subtasks
given below are essentially those in last year's proposal. These subtasks
address extremely complex and difficult problems, problems which will
not be solved in a year. Although some progress already has been made
on most subtasks, work will continue on all.
Subtask
4a. Develop quantitative techniques for projecting geologic information.
We will develop a prototype geologic map cross-section software kit in
Arc8. It will focus on building quantitative, locally compatible, suites
of cross-sections for subsequent assembly (with uncertainties and provenance)
into fully 3-D maps. It will simultaneously display the geologic map and
each cross-section along with toolbars grouping object creation (profiles,
fold axial surfaces, data projection), edit (draw, morph), and validation
(stereonet, fold style) tools. A desired element will be the capability
to extract comparable cross-sections from completed 3-D maps. Existing
software will be reviewed as part of this task. Tool kit will be applied
in Santa Clara Valley (task 2).
Subtask
4b. Develop 3-D inversion techniques for gravity and magnetic data.
The first year we will analyze and develop automated 3-D source-depth
estimators for magnetic bodies. We will inventory available techniques
and develop targeted procedures for differentiating reliable Euler Depth
estimators in 3 dimensions from the overwhelming cloud of spurious estimators.
A successful procedure will have widespread application to the Santa Clara
Valley 3-D geologic map construction effort (task 2) because not only
are magnetic ophiolitic bodies a common component of the Mesozoic basement
beneath the valley, they also tend to occur along and define suture zones
between different nonmagnetic Franciscan terranes. Thus, quantitative
inversion of the magnetic data in 3-D will give both lithologic and structural
information.
Subtask
4c. Develop 'smart' interpolation procedures for subsurface data.
We are admittedly poorly informed about the tools that are available under
this general heading, and so an important effort this year will be to
inventory the current state of the science. One procedure that has become
the workhorse of 3-D geologic studies related to mapping, volume property
definition, aquifer studies, and diapir specification, is the mapping
of interfaces between bodies with different densities by interpolation
between sparsely distributed 'pinned' points constrained by surface gravity
measurements. The present procedure is cumbersome, somewhat limited in
its ability to simulate actual geology, and artificially inflexible. This
first year we intend to totally rework this procedure to dramatically
increase its suitability for solving realistic geologic problems. This
will be directly applicable to the Santa Clara Valley 3-D map task (task2)
because the marked density interface between the Cenozoic and Mesozoic
rocks is a critical element in ground shaking studies, earthquake relocations,
ground water flow modeling, tectonic reconstructions, and numerous other
process investigations.
Subtask4d.
Develop or identify and apply statistical vs deterministic representations
of geology and rock properties. Working from well-constrained interpretations
based upon well logs, outcrop information, and geophysical data, develop
probabilistic models of the distribution of sedimentary rocks and selected
properties of those rocks (e.g. grain size, porosity, density, seismic
wave velocity, hydrologic permeability, etc.) Resulting representations
should capture and fully express both the most likely, expected values
of critical properties of sedimentary rocks at any specified location,
and the range of possibilities and inherent uncertainties. Consequences
of model uncertainties are to be tested for relevance to principal objectives
of the 3-D geologic model.
Planned Outreach:
This task is charged with developing the fundamental
tools and procedures upon which construction of a 3-D geologic map will depend. Most of the subtasks require cutting
edge research. The outreach specifically connected with this task will mostly take the form of colleague interaction
between researchers engaged in related studies. No other formal outreach is planned for this task.
Publications delivered/completed
for this Task:
Fitzgibbon,
T.T., Phelps, G.A., and Jachens, R.C, 2001, GIS tools for the construction
of 3D geologic models, Geological Society of America 2001 Abstracts with
Programs v. 33, p. A-40.
Publications
planned for this task, to be submitted for publication in current or future
fiscal years.
Blakely,
R.J., and others, 2002, A method for estimating depth and shape of tabular,
curvilinear contacts from gravity and magnetic anomalies
2002, Joint
inversion of gravity and magnetic anomalies
ACCOMPLISHMENTS
Current year nonpublication
accomplishments and outcomes:
Progress
was made on many aspects of this task, although much work remains to be
done. Specific interim accomplishments include:
* development
of procedures and techniques to make use of new earthquake catalogues
to define active fault surfaces in 3D (see Highlights)
* initial
redesign of gravity inversion scheme for determining 3D configuration
of basins to explicitly incorporate, as constraints, wells that do not
reach basement. Began fundamental redesign of procedure to eliminate instabilities
caused by background noise in the gravity data and abrupt lateral changes
in the assumed density distribution.
* experimentation
and development of procedures to define the uncertainties in the basin
gravity inversion scheme resulting from uncertainties in the assumed density
distributions
* conceptual
design and initial tests of a 3D Euler deconvolution procedure to estimate
the depth and shape of tabular, curvilinear magnetic bodies from aeromagnetic
data, and to apply geologically intelligent clustering alorithms to refine
the estimates
* conceptual
design of a prototype geologic map cross-section software kit in Arc8
for building quantitative, locally compatible, suites of cross-sections
for subsequent assembly (with uncertainties and provenance) into fully
3-D maps. The geologic map (plan view and draped on 3D topography) and
each cross-section will be live-linked and work with toolbars grouping
object creation (profiles, fold axial surfaces, data projection), edit
(draw, morph), and validation (stereonet, fold style) tools.
Highlights- summary
of the most significant outcome:
The most
significant outcome from this task is the development of techniques and
procedures to define 3D fault surfaces from distributions of seismicity.
Researchers in the Earthquake Hazards Team have recently developed a new,
precise method for determining 3D earthquake locations (the double difference
technique) and have produced a refined earthquake catalogue for the San
Francisco Bay region. This new catalogue defines many of the active faults
with remarkable clarity. We have developed clustering, surface fitting,
and successive overlapping cross section techniques that use these earthquake
locations to define faults. We also have examined the relationship between
fault surfaces defined by earthquakes and surface traces defined by geologic
mapping and find them generally to be compatible. Also, initial tests
indicate that, where examined, the present-day seismicity lies along lithologic
boundaries that represent the long-term locations of the fault surfaces.
So far, we have preliminary surfaces defining the Hayward, Calaveras,
and Loma Prieta faults, have concluded that no separate 'Mission' fault
is required to account for the migration of seismicity from the Calaveras
to the Hayward fault, and have tentatively identified a completely concealed,
probable reverse fault that intersects the bottom of the Cupertino basin
and dips SW toward the San Andreas fault. This fault is of particular
interest to me because my house appears to be nearly above its concealed
tip.
Task 5: Visualization and Release of 3-D Geologic
Maps
Task Leaders:
Task Text
Status: PROPOSED
Task priority: 1
Task Summary and Objectives:
The ultimate
generic product of this project is a 3-dimensional geologic map. Rather
than being a 'hard copy', however, the 3-D geologic map will exist in
a computer as a series of interrelated spatially referenced databases,
interpolation and extrapolation rules, geologic relationships, physical
property assignments, and metadata catalogues. The map will be a 'living'
entity, upgraded as new information is obtained, rather than a static
entity current only to the time of its release. The purpose of this task
is to design and develop a visualization, access, and delivery system
by which users can interact with the 3-D map.
We intend for the 3-D maps to be multipurpose entities,
and thus anticipate that few potential users will want the entire 3-D map, nor will most have the hardware and software
capabilities to handle it. Rather, we foresee two general types of users; 1) those who want a specific component of
the entire map (e.g. the seismic wave propagation modeler who needs velocities and densities everywhere), and 2) those
who need local quantitative information (e.g. the consultant interested in a few specific cross sections or critical
interfaces).
Through the
visualization and release system, the user must be able to: 1) examine
the map in 3-dimensions, 2) extract visual renditions for publications,
presentations, and public relations, 3) extract quantitative volumetric
information for process modeling, 4) examine and extract partial map information
such as quantitative cross sections, point information with associated
metadata, critical surfaces such as faults, depositional surfaces, unconformities,
local properties, volume estimates, etc., all with associated uncertainties,
and 5) accommodate the huge dynamic range capabilities of digital systems,
for example in providing highly detailed information at or near the ground
surface while also including less detailed information in the deeper parts
of the crust.
Work to be undertaken during
the proposal year and a description of the methods and procedures:
Most of the
work on this task will be postponed to later years because many of the
critical details that will need to be incorporated into this visualization,
access, and delivery system will not be known with any precision before
we have an actual, prototype 3-D geologic map in place. There are a few
efforts we plan to initiate this year, however, to insure that when we
have a prototype 3-D map in place, we will be ready to develop the user
interface
The primary software platforms that we will use to develop
the 3-D geologic maps will be earthVision® (Dynamic Graphics, Inc.), and ArcView, Arc/Info (ESRI). These software
packages have many visualization and interactive capabilities and are continually being enhanced. One of the efforts
this year will be to maintain close contacts with the developers of these software packages in order to be aware of
planned changes and expanded capabilities of these systems so that we can be ready to take advantage of the changes,
and also to make these developers aware of our specific needs. Dynamic Graphics, Inc., has been very responsive to
our suggestions in the past, and has actively sought our input into the planning for future software modifications.
A significant component of the new 3-D products will
involve design. A 3-D data set offers an array of possible products: static prints of cross sections, serial sections,
block and fence diagrams; web-based displays of the latter as well as programmed dynamic models; and high-end interactive
models that are query based. Designing these visualization products involve honoring the integrity of the data, utilizing
the power of the visualization tools that are available, and embedding the essence of aesthetic presentation to insure
a complete understanding and a widespread use of the information. A host of products will be designed from the 3-D
data sets. These preliminary products will be floated before various audiences in order to determine appeal and usefulness.
Potential styles and venues include paper fact sheets, digital fact sheets, a website, "stories" for the national
atlas, as well as processed data sets in earthVision® and ARC formats.
Planned Outreach:
Everything
about this task is fundamentally outreach. The focus of all the efforts
will be to deliver a useful and effective product to the customers.
ACCOMPLISHMENTS
Current year nonpublication accomplishments and outcomes:
* By the
end of FY2001, we will produce 4 science stories that will provide a view
of the geologic evolution of the San Francisco Bay area in general and
the Santa Clara Valley in particular. These stories will provide the background
for subsequent stories that will focus on the process of 3D mapping and
its uses. The stories are intended to be animations that will add a 4th
dimension to the 3D maps, and will be included on the project website
and likely in the National Atlas.
* We worked
with Skip Pack of Dynamic Graphics, Inc., exploring methods for 3D display
of uncertainties associated with surfaces. Several methods are possible,
with a 'peg-board' display (the length of the peg normal to the surface
reflecting the uncertainty) seem very promising.
* We began
evaluating GeoExpress 2000, a proprietary 3D visualization and data manipulation
package built on medical imaging technology. It has a very flexible interface
that allows the user to place point, line, surface, cross-section, or
volume data into a projected 3D viewing space. Constructing a view is
like building a circuit diagram for the flow of data into a frame. The
circuit is built of modules that typically have one or more input and
output ports. This system seems to have the potential to allow users of
the 3D geologic maps to extract personally tailored subsets of the full
3D map.
Task 6: Salinas Valley Neogene basin analysis
Task Leader:
Graymer, Russell W.
rgraymer@usgs.gov
345 Middlefield Rd
Menlo Park, CA 94025
Phone: (650)329-4988
FAX: (650)329-4936
Task Text
Status: PROPOSED
Task priority: 1
Task Summary and Objectives:
Northern
California is the type area for many plate tectonic models now generally
accepted (arc-forearc systems, accreted terranes, transform-fault systems).
However, fundamental questions remain about the tectonic system, especially
the dynamics of the plate margin, the shaping of the landscape, past and
present, and the relation between the dynamic system and geologic hazards.
Furthermore, Northern California contains a unique intersection of resources,
urban expansion, economic importance, and geologic processes, yet basic
geologic data sets are fatally outdated in much of the area. The Salinas
Valley region provides the perfect site to address both scientific and
societal issues. Northern Salinas Valley is rapidly urbanizing, the central
and southern parts hold known and potential oil fields, and the basin
as a whole typifies the plate margin. Petroleum production has generated
a wealth of well data and seismic profiles. Dwindling groundwater resources
are utilized for agriculture and the growing population. The region is
bounded on the northeast by the San Andreas Fault, on the southwest by
the less-studied Rinconada and Nacimiento faults. The hillsides surrounding
much of the valley are underlain by Miocene and younger sedimentary rocks
similar to those known to be susceptible to landslides in the San Francisco
Bay region. The young rocks and fault zones also make the region an excellent
laboratory for addressing the scientific questions associated with transpressional
plate margin. Fossils in the Salinas Valley area crop out extensively
but have been little studied. These fossils will give insight into stratigraphy,
fault movement, and paleogeography of the Valley. An important problem
of Quaternary history of the area is the nature of the major drainage
change that took place from the Great Valley of California to the Pacific
Ocean in middle Pleistocene time, controlled by both movement on the San
Andreas Fault and Pleistocene climate change.
Work to be undertaken during
the proposal year and a description of the methods and procedures:
Because the
Salinas Valley region is roughly equivalent in size to the San Francisco
Bay region, a multi-year effort is proposed, including 2- and 3-D geologic
mapping, basin analysis, surficial deposits mapping, paleontological studies,
and structural analyses. The initial year's effort will combine regional
geologic mapping and paleontological studies. A new geologic map and map
database of the region will be made, composed of newly collected geologic
information in critical areas augmented by published and unpublished previous
work. New and compiled data will be integrated into geologic map databases
in Arc/Info using standard methodology developed by the San Francisco
Bay Geologic Mapping Project. High quality digital geologic maps will
be produced from the databases via ArcPlot. FGDC Metadata will be produced
to accompany each map database. Maps and map databases will be published
as MF series maps via the Internet and USGS Map-on-Demand. The new work
will continue the collaborative work of Graymer with USGS emeritus scientists
Brabb, Clark, and Jones, and will include new structural, tectonic, and
stratigraphic interpretations. These maps will also continue our work
to address questions of development and ongoing activity of the San Andreas
Fault System in the region. Paleontological studies will focus on poorly
studied Neogene strata, which should record a major restructuring of the
Pacific/NA plate margin and movement along the San Andreas Fault. Existing
and new molluscan and microfossil data will be compiled and analyzed,
and preliminary reports in the OF series will be produced. Biostratigraphic
data will be combined with structural data collected in geologic map studies
to produce a structural framework for the Salinas Valley basin analysis.
In FY03 we
will propose to build on the regional framework developed in FY02 to build
a 3-D geologic map and basin analysis. We envision the integration of
subsurface data from petroleum exploration, potential field geophysical
data, and Quaternary surficial deposits mapping with ongoing geologic
mapping and paleontologic studies.
Planned Outreach:
The web-page
developed for the San Francisco Bay region Project (SFGEO) will be expanded
to include the geology of the Salinas Valley region. This website continues
to provide easy access to our geologic map products to academic, private,
and government collaborators and customers, as well as a variety of materials
designed for the general public (e.g. a web version of a pamphlet on how
to read a geologic map originally designed for the Menlo Park Open-House).
Ties will
be sought with the Northern California Landslide Working Group to pursue
landslide hazard analyses. Ongoing collaboration with the Earthquake Hazards
Team to pursue earthquake hazard analyses established in the San Francisco
Bay region will be extended to the Salinas Valley area. Furthermore, ties
will be pursued with the academic community pursuing research in the area
(e.g. Steve Graham, Stanford Univ.).
Task scientists
will also continue to provide consultation and advice on geologic and
paleontologic questions to the academic and private sector and the general
public via e-mail and phone contact and field trips.
Publications planned for this
task, to be submitted for publication in current or future fiscal years.
Langenheim,
V.E., and others, 2002, Isostatic residual gravity map of the Monterey
30' X 60' quadrangle, California
Geographic area of task:
United States,
Pacific Coastal States, CA
Polygon Lat/Long: 37/122 35.75/120.75
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