Earthquake swarm near Obsidian Butte, CA

Last updated: 2018-03-26 17:50:55 UTC

Global view of quake


The Anza group at the University of California San Diego operates a broadband seismograph network consisting of 17 three component broadband seismograph stations centered near Anza, California (see map).

On Monday, March 15th, 2004 around 4:00 PM (PST) we recorded a swarm of earthquakes (from ml 1.99 to ml 3.82) located near Obsidian Butte.

If you felt the any of these earthquakes, the USGS would like to know. Please add to the USGS "Did you feel it?" page.

View the most recent map of local events near San Diego or a slightly wider regional view of events recoded by ANZA, or a map of events recoded by ANZA from around the globe.

Initial source parameters for the recent events are shown below. The epicentral distance (distance separating the epicenter of the largest event and the closest station in the recording network) for Anza is 76 km (0.68 degrees).

This map shows the mainshock (red star) and any associated aftershocks (orange stars). Anza network stations are blue triangles.

Global mecator event map

Latitude Longitude Origin time (UTC) Origin time (PDT) Depth (km) ml Author
33.1963 -115.5647 3/16/04 (076) 00:05 3/15/04 (075) 16:05 22 2.38 UCSD:vladik
33.2319 -115.5421 3/16/04 (076) 00:20 3/15/04 (075) 16:20 17 2.52 UCSD:vladik
33.1982 -115.5496 3/16/04 (076) 00:22 3/15/04 (075) 16:22 24 2.83 UCSD:vladik
33.1959 -115.5418 3/16/04 (076) 00:30 3/15/04 (075) 16:30 23 3.82 UCSD:vladik
33.1759 -115.5350 3/16/04 (076) 00:33 3/15/04 (075) 16:33 20 3.82 UCSD:vladik
33.1929 -115.5682 3/16/04 (076) 00:45 3/15/04 (075) 16:45 25 1.99 UCSD:vladik

* The location and magnitude determined for this event are preliminary and are subject to change upon further review of seismic data.

You may also view a plot showing

Of local interest:
We operate a broadband station on Mt. Soledad. At 16:33 (PST) station SOL recorded the P wave from the largest event. Here is a view of that event as picked by our analyst. A pink "P" indicates a P wave arrival, a pink "S" indicates an S wave arrival.

3 component seismometer recordings at Soledad

View a larger image showing the waveforms recorded at Mt. Soledad.

Visit the IRIS website with additional links to seismic data for this event.

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Learn more about the Anza group (including who works here, other networks, nuclear tests in China/India/Pakistan).
Learn more about the ANZA network (includes more station information, research, etc).

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