The volcanoes of Hawaii Hawaiian volcanoes typically evolve in four stages as volcanism waxes and wanes: (1) early alkalic, when volcanism originates on the deep sea floor; (2) shield, when roughly 95 percent of a volcano's volume is emplaced; (3) post-shield alkalic, when small-volume eruptions build scattered cones that thinly cap the shield-stage lavas; and (4) rejuvenated, when lavas of distinct chemistry erupt following a lengthy period of erosion and volcanic quiescence. During the early alkalic and shield stages, two or more elongate rift zones may develop as flanks of the volcano separate. Mantle-derived magma rises through a vertical conduit and is temporarily stored in a shallow summit reservoir from which magma may erupt within the summit region or be injected laterally into the rift zones. The ongoing activity at Kilauea's Pu‘u ‘O‘o cone that began in January 1983 is one such rift-zone eruption. The rift zones commonly extend deep underwater, producing submarine eruptions of bulbous pillow lava.
The Japan Marine Science and Technology Center (JAMSTEC) funded and led a four-year collaborative survey of the underwater flanks of Hawaii's shield volcanoes. This exploration, involving scientists from the U.S. Geological Survey (USGS) and other Japanese and U.S. academic and research institutions, utilized manned and unmanned submersibles, rock dredges, and sediment piston cores to directly sample and visually observe the sea floor at specific sites. Ship-based sonar systems were used to more widely map the bathymetry from the sea surface. The state-of-the-art multibeam sonar systems, mounted
on the hull of GPS-navigated research vessels, convert the two-way travel
times of individual sonar pings and their echoes into a line of bathymetry
values across the ship track. The resulting swaths across the ocean bottom,
obtained along numerous overlapping ship tracks, reveal the sea floor
in stunning detail. The survey data collected by JAMSTEC form the basis
for the bathymetry shown on the map, augmented with bathymetric data from
other sources. Bathymetry that is predicted from variations in sea-surface
height, observable from satellites, provides the low-resolution (fuzzy)
bathymetry in between ship tracks. Subaerial topography is from a USGS
30-m digital elevation model of Hawaii. Historical lava flows are shown
in red. Prominent terraces (shown in orange and yellow) illustrate the larger size of the islands in the past; O‘ahu and the Maui-Nui complex (Maui, Moloka‘i, Lana‘i, and Kaho‘olawe islands, and Penguin Bank), in particular, are mere vestiges of their former extent. Lo‘ihi, the youngest volcano in the chain, has not yet reached the sea surface. Fields of blocky debris, such as Ko‘olau's Nu‘uanu Slide, were created by catastrophic landslides, which carried large parts of some volcanoes as much as 200 km across the sea floor. Slower-moving, sediment-blanketed slumps, in contrast, typically develop ridges that parallel the paleocoastlines, such as Haleakala's Hana Slump. Eruptions along the submarine part of a volcano's rift zone produce a rugged morphology, as at Kilauea's Puna Ridge. Numerous seamounts of Late Cretaceous age (approximately 80 Ma) are scattered across the deep sea floor and are unrelated to the hot spot that supplies Hawaii's volcanoes. |
Download this map as a PDF file (3.6 MB)
Download the bathymetry image from this map as a PDF file (3.6 MB)
Submarine bathymetry and subaerial topography data sources:
Japan Marine Science
and Technology Center, Yokosuka, Japan
U.S. Geological Survey, Menlo
Park, California
Monterey Bay Aquarium
Research Institute, Monterey, California
University of Hawai‘i, School
of Ocean and Earth Science and Technology, Honolulu, Hawaii
National Geophysical
Data Center, Boulder, Colorado
Scripps Institution of Oceanography,
San Diego, California
U.S. Army Corps of Engineers,
Mobile, Alabama
Global seafloor topography
(predicted bathymetry)
For questions about the content of this report, contact Joel Robinson
Download a current version of Adobe Reader for free.
| Help
| PDF help
| Geopubs main page | I
Maps |
| Privacy
Statement | Disclaimer
| Accessibility |
| Geologic
Division | Volcano Hazards Team
|
This map is also available in print from:
USGS Information Services, Box 25286,
Federal Center, Denver, CO 80225
telephone: 303-202-4210; e-mail: infoservices@usgs.gov