New Mexico, although it is over 1000 kilometers from the nearest plate tectonic boundary (the San Andreas fault in California), is a moderately seismically active region, with earthquakes occurring in most parts of the state. The Socorro area has been the most seismically active portion of New Mexico during at least the past 100 years, and the largest documented earthquakes in New Mexico's history ocurred near Socorro in 1906.

Click on the New York Times headline to see the 1906 newspaper reports of the large earthquakes of July, 1906.

The 1906 earthquakes near Socorro were strongly felt as far away as El Paso, TX and Las Vegas, NM. A scientific study of these earthquakes by H.F. Reid (who also did fundamental research on the great 1906 San Francisco earthquake) was published in the first issue of the Bulletin of the Seismological Society of America (1911). The intensities contoured on the map are estimates of maximum ground acceleration, which ranged from III (about 1% of acceleration due to gravity) near El Paso to VIII (about 25% of acceleration due to gravity) near Socorro.

Click on the front page of the Bulletin of the Seismological Society of America to see two pages from Reid's study of the 1906 Socorro earthquakes.

During the past 35 years, close to 50% of the seismic energy generated by earthquakes in New Mexico has occurred in a region centered near Socorro, encompassing only approximately 2% of the state's total land area.

This relatively high rate of earthquake activity is due to a huge body of molten rock (magma) residing 19 kilometers beneath the Socorro portion of the Rio Grande rift valley. Seismic waves are clearly reflected from the upper surface of the Socorro magma body, and demonstrate that it has an upper surface area in excess of 3400 square kilometers (1300 square miles).

Observations of seismic waves from distant earthquakes which propogate upwards through the magma body and observations of uplift indicate that it is presently being supplied with fresh magma from the Earth's mantle. The present inflation of this body creates a surface uplift of several millimeters per year), and the associated stress creates earthquakes in the region.

Click the image on left for a map of the naturally occurring earthquakes in New Mexico (1962-1998) that illustrates the concentration of seismicity in the Socorro region. Surface uplift rate in the region is shown in the accompanying satellite interferometric synthetic aperture radar (INSAR) image.

Click on the New Mexico flag to see the seismicity of New Mexico compared to some other regions. While not exceptionally active, New Mexico has a significant probability of strongly felt earthquakes.

The New Mexico map available at left shows seismic stations currently operated by the New Mexico Tech Geophysics Program.

 

Click on the left image for a larger view of the Socorro magma body (red), local microearthquakes (circles; 1975–1995) and land surface. The example local earthquake seismogram (yellow) shows strong seismic reflections (PzP, SzS) from the nearly flat upper surface of the body.

 

The table below shows the thirty largest historical earthquakes in New Mexico (through August, 2003).

References | Credits

Download a poster with the above information on it. Two sizes are available.

32" x 49" 36" x 56"
PDF (1.83 MB), Adobe Illustrator (20 MB) PDF (1.96 MB), Adobe Illustrator (20 MB)

 

Page last updated November 17, 2004 by Webmaster