1990 Upland earthquake
Total damage | $12.7 million [2] |
---|---|
Max. intensity | MMI VII (Very strong) [3] |
Peak acceleration | 1.05 g [4] |
Casualties | 30 injured [2] |
The 1990 Upland earthquake occurred at 15:43:37 local time on February 28 with a
Tectonic setting
In the Transverse Ranges west of the right-lateral San Andreas Fault System, some faults exhibit left-lateral slip, including some at the boundary of the Los Angeles Basin and the Transverse Ranges.[5]
Earthquake
While several examinations of earthquake focal mechanisms in the Upland area showed both thrust and strike-slip faulting on opposite ends of the San Jose Fault, the mechanism of the 1990 event showed pure left-lateral motion on a steeply-dipping (70°) and northeast-striking fault. Field investigations revealed that the bilateral rupture did not reach the surface.[6]
Strong motion
The shock was felt from
Damage
Rockslides left some roads closed in the San Gabriel Mountains and Pomona city hall was heavily damaged. In Claremont some buildings were damaged, but only one building in Upland's historic downtown area was tagged for non-occupation. Those that were injured suffered cuts and bruises (mainly from falling objects) but two men were injured as a result of a landslide.[7][8]
See also
- List of earthquakes in 1990
- List of earthquakes in California
- List of earthquakes in the United States
References
- ^ a b c d ISC (2016), ISC-GEM Global Instrumental Earthquake Catalogue (1900–2012), Version 3.0, International Seismological Centre
- ^ a b c USGS (September 4, 2009), PAGER-CAT Earthquake Catalog, Version 2008_06.1, United States Geological Survey
- doi:10.7289/V5TD9V7K
- ^ a b Etheredge, E. C.; Acosta, A. V.; Foote, L. J.; Johnson, D. A.; Maley, R. P.; Porcella, R. L.; Switzer, J. C. (1990), Strong-motion recordings from the ML=5.5 Upland, California earthquake of February 28, 1990, Open-File Report 90-311, United States Geological Survey, pp. 1–5
- ISBN 978-0521190855
- ^ Warren, J.; Roderick, K. (March 1, 1990). "Quake Damage at Least $20 Million : New Slide Recloses Mt. Baldy Road; Aftershocks Continue". Los Angeles Times.
- ^ Malnic, E.; Sahagun, L. (March 1, 1990). "Quake Hits Vast Area of Southland : Seismic: Epicenter near Upland. Some damage but only minor injuries reported. Estimated strength of temblor varies from 5.5 to 6.1". Los Angeles Times.
External links
- M5.5 – 6km NNE of Claremont, CA – United States Geological Survey
- The International Seismological Centre has a bibliography and/or authoritative data for this event.