Bermuda earthquake of March 24, 1978: A significant oceanic intraplate event

Journal Article · Mon Aug 10 00:00:00 EDT 1981 · J. Geophys. Res.; (United States)

DOI:https://doi.org/10.1029/JB086iB08p07027· OSTI ID:5939921

Stewart, G S; Helmberger, D V

The Bremuda earthquake (Mapprox.6) occured near the westerly extension of the Kane Fracture Zone roughly 370 km southwest of the island of Bermuda. It is one of the largest oceanic intraplate earthquakes to occur off the eastern coast of North America. Because of its size and location, it has provided an excellent set of WWSSN body waves. They can be used to infer its depth and faulting parameters by waveform modeling techniques. The results indicate a north-northwest striking thrust mechanism (strike = N20 /sup 0/W, dip = 42 /sup 0/NE, rake = 90/sup 0/) with the hypocenter located at a depth of 11 km, which for an oceanic crust places it predominantly in the mantle. The event had a seismic moment of 3.4 x 10/sup 25/ dyne cm, and its time history was modeled with a symmetric trapezoidal time function 3 s in duration. The north-northwest strike of the event is in good agreement with the bathymetry of the area, the epicenter being close to the southwestern edge of the Bermuda Rise. The strike of the event is also close to that of the inferred extensions of the present ridge fracture zones in the region. The strike of the event is also close to that of the inferred extensions of the present ridge fracture zones in the region. The presence of fracture zones is indicative of local weak zones in the lithosphere. The Bermuda earthquake most likely is associated with one of these zones of weakness and is the result of the application of present day stress imposed on the region by the North American plate in the direction of its absolute motion. This is an important event in terms of understanding and estimating seismic hazard on the eastern seaboard of North America.

• Research Organization: Seismological Laboratory, California Institute of Technology, Pasadena, California 91125
• OSTI ID: 5939921
• Journal Information: J. Geophys. Res.; (United States), Vol. 86:B8
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
BERMUDA
EARTHQUAKES
HYPOCENTERS
EARTH MANTLE
EPICENTERS
OCEANIC CRUST
PLATE TECTONICS
RIFT ZONES
SEA-FLOOR SPREADING
SEISMIC WAVES
WAVE FORMS
EARTH CRUST
EUROPE
GEOLOGIC STRUCTURES
ISLANDS
SEISMIC EVENTS
TECTONICS
UNITED KINGDOM
WESTERN EUROPE
580201* - Geophysics- Seismology & Tectonics- (1980-1989)