1984 Morgan Hill earthquake
|Date||April 24, 1984|
|Magnitude||6.2 Mw |
|Depth||8 km (5.0 mi) |
|Areas affected||Santa Clara Valley
|Total damage||$8 million |
|Max. intensity||VIII (Severe) |
|Peak acceleration||1.3g at Coyote Dam |
|Casualties||27 injured |
The 1984 Morgan Hill earthquake (also Halls Valley earthquake) occurred with a moment magnitude of 6.2 on April 24 at 1:15 p.m. local time in Northern California. The epicenter of the shock was located near Mount Hamilton in the Diablo Range of the California Coast Ranges. Nearby communities (including Morgan Hill) sustained serious damage consistent with a maximum Mercalli Intensity of VIII (Severe), with financial losses of around US$8 million.
The earthquake occurred along the Calaveras Fault, with the epicenter 16 kilometers (9.9 mi) northeast of San Jose, and at a depth of 8 km (5.0 mi). The outline of aftershocks show that the rupture propagated southeast over a 25 km (16 mi) section of the fault, as far as San Martin.
The earthquake was reported to be felt over an area of 120,000 square kilometers (46,000 sq mi). Morgan Hill was the worst affected, with a number of mobile homes sliding off foundations, and moderate damage to several masonry buildings in the city. The communities of San Jose, San Martin and Coyote were some areas that experienced minor damage. In Santa Clara County, over 550 buildings were reported to have received at least minor damage.
- ISC (2014), ISC-GEM Global Instrumental Earthquake Catalogue (1900-2009), Version 1.05, International Seismological Centre
- Stover & Coffman 1993, p. 97
- Cockerham, R.S.; Eaton, J.P. (1987), "The Earthquake and its Aftershocks, April 24 through September 30, 1984", The Morgan Hill, California, Earthquake of April 24, 1984, U.S. Geological survey Bulletin 1639, United States Geological Survey, p. 17
- Stover & Coffman 1993, p. 175
- Shakal, A.; Gay, Jr., T. E.; Sherburne, R. (August 1984), "Morgan Hill earthquake - Caused record shaking force", California Geology (California Division of Mines and Geology): 163
- "The Morgan Hill Earthquake of 1984". Earthquakes in Your Backyard - And Tsunamis. Archived from the original on 2009-06-01. Retrieved 2009-05-29.
- Toppozada, Tousson R. "Morgan Hill Earthquake of April 1984". California Division of Mines and Geology. Archived from the original on 2009-06-01. Retrieved 2009-05-29.
- "Remembering the 1984 Morgan Hill Earthquake". West Coast Earthquakes. Archived from the original on 2009-06-01. Retrieved 2009-05-29.
- Stover, C. W.; Coffman, J. L. (1993), Seismicity of the United States, 1568-1989 (Revised), U.S. Geological Survey Professional Paper 1527, United States Government Printing Office