The CREST Project
The Consolidated Reporting of EarthquakeS and Tsunamis (CREST) is a project to improve
the nation's ability to rapidly assess the likelihood of a damaging tsunami.
Real-time data from CREST and USGS National Seismic Network (USNSN) stations will be transmitted
to NOAA's West Coast/Alaska Tsunami Warning Center (WC/ATWC) in Palmer, Alaska, and to
the Pacific Tsunami Warning Center (PTWC) in Eva Beach, Hawaii. Real-time data from these stations can be viewed on
Webicorders from Westcoast, AK and HI.
The modern monitoring equipment is being installed at seismic stations in Cascadia, Alaska, and Hawaii will
improve the timeliness and quality of seismic data from areas where tsunamigenic earthquakes can occur.
The tsunami warning centers are operated by the National Oceanic and Atmospheric Administration (NOAA), and
the CREST project is funded by NOAA's National Tsunami Hazard Mitigation Program. The CREST stations will either be operated by universities under contract to the USGS (United States Geological Survey), or be operated directly
by the USGS. 2000 Status Report
Time is of the essence in issuing a tsunami warning for
earthquakes occurring in coastal waters of the US because tsunami waves can
reach land in less than 20 minutes. Data from CREST stations will greatly reduce
the time required to obtain reliable estimates of earthquake location and
magnitude, which govern the initial decision to issue a warning to evacuate
populations from low-lying regions along the coast. With the CREST system in
place, alerts can be generated within minutes of the possibly
tsunamigenic event.
After issuing an initial warning, the Warning Centers use
additional data from tide gauges and deep ocean pressure sensors to
support their decision to either cancel or continue the warning (and refine the extent of the warning area). Rapid analysis of CREST data
will help assess the tsunamigenic potential of the earthquake.
In addition to life-saving tsunami warnings,
the CREST project will provide
rapid and reliable information for state Offices of Emergency Services.
This information is essential to
identify the epicentral region and
guide response activities.
Finally, data from large earthquakes
recorded by CREST instruments will be used to improve the seismic
requirements of the Uniform Building Code, which in turn will reduce the loss
of life in future earthquakes.
CREST Installation Description
Most of the instrumentation in use by regional seismic
networks was installed in the 1970's and is unsuitable for use by the Tsunami
Warning Centers. To increase the usefulness of regional seismic network data to
the Warning Centers, CREST seismic stations must have a frequency response and
dynamic range capable of recording the entire range of earthquake ground
motion. Consequently, where we are upgrading equipment at existing seismic
stations, we are replacing all of the hardware with modern equipment.
In general, we prefer to install the
equipment at very "quiet" locations far from cultural noise, roads, and shorelines
where surf activity generates microseisms.
At each CREST
site we install both a strong-motion accelerometer and a broadband seismometer
to ensure that on-scale data are obtained for local strong shaking as well as
for regional and teleseismic
earthquakes.
The CREST installation usually consists of:
- A footlocker-sized seismometer box -- This consists of a concrete
pad to attach seismometers to (this can be a concrete floor, or a small slab about 2 feet square and 4 inches thick), thermal insulation, and a metal security box around the seismometers (depending on site security).
- Another footlocker-sized box containing a digital datalogger,
communications equipment, and backup power source (also secured against shaking).
- Cabling between the two boxes (can be buried)
- Cabling to GPS antenna (antenna must be outdoors with view of sky)
- Connection to line power
- Communication connection:
- Leased-line modem (telephone line) OR
- Microwave link if available (with leased-line modem) OR
- Radio link (Spread-spectrum radio with leased-line modem) and pole-mounted 2' by 6" Yagi antenna OR
- Internet connection
PNSN Summer 2000 CREST Installation Plan
As of mid-May, 2000, the PNSN is operating 3 CREST stations in Washington, and
2 CREST stations in Oregon. We plan to install two additional sites in Washington, and six in Oregon during summer, 2000. See MAP. An
operational layout is available at:
