Press Release

Nevada Seismological Laboratory

20 September 2004

11:00 AM PDT

M 5+ Earthquakes near Mono Lake, California.

A magnitude 5.0 earthquake was recorded today (Monday, September 20) at 9:51 AM PDT near Mono Lake, California, nearly on the Nevada border. It was located at 38.024 N, 118.642 W, with a preliminary depth of 5.5 kilometers (~3 miles). This earthquake follows two larger events on Saturday, September 18, at 4:02 and 4:43 PM PDT; their magnitudes were 5.5 and 5.4, respectively. All three events are within roughly 3 km (~2 miles) of one another. The location of these events is roughly 30 miles south of Hawthorne, Nevada, and 30 miles northwest of Mammoth Lakes, California. Numerous aftershocks (nearly 1000 so far) of the Saturday events have been observed at the Nevada Seismological Laboratory. The largest one, which occurred today, is abnormally large for an aftershock. These events are likely associated with the Huntoon Valley Fault which crosses the California-Nevada border in this area.

The data reported here have been reviewed. For more information, contact the Nevada Seismological Laboratory, (775) 784-4975. The free pamphlet "Earthquakes in Nevada and How to Survive Them," is available on request. The NSL operates a statewide network of seismographic stations and investigates the sizes, frequencies of occurrence, and distribution of earthquakes in the region, and other problems related to seismic risk in Nevada. Visit the NSL web site at www.seismo.unr.edu for further information.