Magnitude 3.9 quake near El Cajon, CA

Last updated: 2018-03-26 17:50:58 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 Tuesday, April 12, 2005 at 4:06 AM (PDT) we recorded a quake (preliminary ml 3.9) located near El Cajon. The earthquake was felt widely throughout San Diego county, but there have been no reports of damage.

If you felt the quake, 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 event are shown below. The epicentral distance (distance separating the epicenter and the closest station in the recording network) for Anza is 23 km (0.21 degrees).

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

Event Map

Global mecator event map

Event Parameters

Latitude Longitude Origin time (UTC) Origin time (PDT) Depth (km) ml Author
32.7547 -116.8209 04/12/05 (102) 11:06.46 04/12/05 (102) 4:06 AM 21 3.9 CalTech

* 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 04:06 (PDT) station SOL recorded the P wave from this event. Here is a view of that event as picked by our analyst. A red P indicates a P wave arrival, a red 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 EarthScope USArray ANF website with additional links to seismic data for this event.

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

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

Virtual 3-D Model

El Cajon Model Screendump

Screen shot of the virtual 3-D model

You may download an interactive 3-D model by right-clicking (Windows) or CTRL-clicking (Mac) the links below and choosing "Download file to disk". The file has been compressed to ~10MB with gzip and must be expanded before use. Alternatively you can download the uncompressed scene file (18MB). To view the virtual model, you need to download iView 3D - a free viewer available from IVS for Windows, Mac, Linux, Sun and SGI platforms. Click here to download the viewer.

The model consists of an outline of the state of California and major highways (purple lines). The region of San Diego county has high-resolution topography. Brown lines are major faults in the state. The model and its component parts have been accurately geo-referenced. The earthquake hypocenter is plotted as a red diamond. The green lines depict ANZA station telemetry paths. Historical earthquakes are plotted as small white spheres/dots (they clearly define the San Andreas Fault Zone) and earthquakes of magnitude 4.0 and greater are depicted by pink spheres.

Once the file has loaded into iView3D, navigation is accomplished by using the mouse. Click the left mouse button and drag left or right to rotate about the vertical axis. Click the left mouse button and drag up or down to rotate about the horizontal axis. Translations and scaling are both accomplished with either the middle or right mouse buttons in a two-step process.

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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).

URL: [Last updated: 2018-03-26 17:50:58 UTC]