U.S. DEPARTMENT OF THE INTERIOR U.S. GEOLOGICAL SURVEY OPEN-FILE REPORT 2010–1083-F Revised September, 2011 Seismicity of the Earth 1900–2010 TECTONIC SUMMARY Located atop three of the large tectonic plates, Mexico is one of the world's most seismologically active regions. The Mexico and Vicinity relative motion of these crustal plates causes frequent earthquakes and occasional volcanic eruptions. 1 1 2 1 1 3 1 Compiled by Harley M. Benz, Richard, L. Dart, Antonio Villaseñor, Gavin P. Hayes, Arthur C. Tarr, Kevin P. Furlong, and Susan Rhea Most of the Mexican landmass is on the westward moving North America plate. The Pacific Ocean floor south of PRE-INSTRUMENTAL SEISMICITY 1500–1899 Mexico is being carried northeastward by the underlying Cocos plate. Because oceanic crust is relatively dense, 1 U.S. Geological Survey Events causing deaths when the Pacific Ocean floor encounters the lighter continental crust of the Mexican landmass, the ocean floor is 2Institute of Earth Sciences, CSIC, Barcelona, Spain 110° 100° 90° 3Department of Geosciences, Pennsylvania State University, State College, PA 16802 USA 1812 subducted beneath the North America plate creating the deep Middle America trench along Mexico's southern coast. Also as a result of this convergence, the westward moving Mexico landmass is slowed and crumpled creating UNITED STATES the mountain ranges of southern Mexico and earthquakes near Mexico's southern coast. As the oceanic crust is 2011 pulled downward, it melts; the molten material is then forced upward through weaknesses in the overlying 120° 115° 110° 105° 100° 95° 90° 85° 1887 continental crust. This process has created a region of volcanoes across south-central Mexico known as the SAN ANDREAS Los 30° 30° Cordillera Neovolcánica. Santa Cruz Is. Angeles Santa Rosa Is. Atlanta The area west of the Gulf of California, including Mexico's Baja California Peninsula, is moving northwestward FAULT Phoenix MEXICO with the Pacific plate at about 95 mm per year. Here, the Pacific and North America plates grind past each other Santa Catalina Is. creating strike-slip faulting, the southern extension of California's San Andreas fault. In the past, this relative plate San motion pulled Baja California away from the coast forming the Gulf of California and is the cause of earthquakes in San Clemente Is. Diego Mexicali Dallas the Gulf of California region today.

Mexico has a long history of destructive earthquakes and volcanic eruptions. In September 1985, a magnitude 8.1 El Paso UNITED STATES 1568 earthquake killed more than 9,500 people in Mexico City. In southern Mexico, Volcán de Colima and El Chichón 1864 erupted in 2005 and 1982, respectively. Paricutín volcano, west of Mexico City, began venting smoke in a cornfield in 1943; a decade later this new volcano had grown to a height of 424 meters. Popocatépetl and Ixtaccíhuatl 20° 1870 20° BELIZE volcanos ("smoking mountain" and "white lady," respectively), southeast of Mexico City, occasionally vent gas that Baja California Mobile GUATEMALA can be clearly seen from the City, a reminder that volcanic activity is ongoing. In 1994 and 2000 Popocatépetl Austin 1773 1874 HONDURAS renewed its activity forcing the evacuation of nearby towns, causing seismologists and government officials to be Jacksonville 1873 1773 concerned about the effect a large-scale eruption might have on the heavily populated region. Popocatépetl volcano 30° 30° 1873 San Houston New Orleans 1854 NICARAGUA last erupted in 2010. I. de la Guardia Antonio n a F DATA SOURCES AND MAP DISPLAY

Hermosillo i Gulf of California p Isla Guadelupe I. Tiburon p 110° 100° 90° (Mexico) i The earthquake locations shown on the main map (left) and on the depth profiles (lower left) are taken from the i s s Chihuahua M i s s global 1900–2007 Centennial catalog (Engdahl and Villaseñor, 2002) and a catalog of high-quality depth determinations for the period 1964–2002 (Engdahl, personal comm., 2003) . I. Cedros Tampa Major earthquakes (7.5=M=8.2) are labeled with the year of occurrence, while earthquakes (8.0=M=8.2) are labeled with the year of occurrence and also denoted by a white outline (Tarr and others, 2010).

The Seismic Hazard and Relative Plate Motion map (below) shows the generalized seismic hazard (Giardini and others, 1999) and relative plate motion vectors (open arrows with labels; DeMets and others, 1994).

t n S e i g m The pre-instrumental seismicity map (upper left) shows approximate locations of events based on macro-seismic Monterrey s b e p MEXICO e E s c a r reports and field investigations (NOAA National Geophysical Data Center database of significant earthquakes, Saltillo C Pescadero Trough Gulf of Mexico 2010). These are earthquakes for which deaths were reported. e M 25° d a 25° g r d Culiacan Base map data sources include GEBCO 2008 shaded relief, Volcanoes of the World dataset (Siebert and Simkin, o a Key West s l e n 2002), plate boundaries (Bird, 2003), and geographic information from Digital Chart of the World (1992) and ESRI a Florida T Keyes r E (2002). Subduction slab contours are colored and labeled as to depth (Hayes and Wald, 2010). s Durango e c Sigsbee Deep n a r c p h m e Mexico Basin n REFERENCES t Havana

San Jose Canyon Ulloa Bird, Peter, 2003, An updated digital model of plate boundaries: Geochemistry Geophysics Geosystems, v. 4, no. 3, 52 p. Knoll Campeche Bank CUBA Mazatlan San Luis Tampico DeMets, Charles, Gordon, R.G., Argus, D.F., and Stein, Seth, 1994, Effect of recent revisions to the geomagnetic reversal Basin Potosi , Aguascalientes time scale on estimates of current plate motions: Geophysical Research Letters, v. 21, p. 2191–2194. Isla María Madre Isla del la Juventud Isla María Magdalena Digital Chart of the World, 1992: , last Islas Marías http://earth-info.nga.mil/publications/specs/printed/89009/89009_DCW.pdf P A C I F I C Isla María Cleofas accessed Mar. 9, 1996. O C E A N Tres Marias Merida Basin Guadalajara Engdahl, E.R., and Villaseñor, Antonio, 2002, Global seismicity: 1900–1999, in Lee, W.H.K., Kanamori, Hiroo, Jennings, Queretaro Bay of , Banderas canyon P.C, and Kisslinger, Carl, eds., International Handbook of Earthquake and Engineering Seismology: San Diego, Isla Cozumel , A' Campeche Yucatan Volcán de Colima Calif., Academic Press, v. 81(A), Chap. 41, p. 665–690. 20° Morelia Mexico 20° 1932 Peninsula i n s m ESRI, 2002, ESRI data and maps: Redlands, Calif., ESRI. Available at . Islas Revillagigedo City a Cay http://www.esri.com/data/data-maps/index.html 1932 Toluca B (Mexico) Isla Benedicto Vera cru z n Grand Cayman I. Paricutin Puebla a 1995 2003 Cuernavaca t Isla Roca Partida 1941 a GEBCO, 2008, The GEBCO_08_Grid, ver. 20091120, last accessed January 8, 2010 at http://www.gebco.net/. Cayo Norte c F.Z. Isla Socorro 1985 Ixtaccihuatl u Clarion 1973 Popocatépetl Y Isla Clarión B' Cayo Lobos 1908 Cayman Ridge Giardini, D., Grünthal, G., Shedlock, K., Zhang, P., and Global Seismic Hazards Program, 1999, Global Seismic Hazards 60 , 1985 100 Villahermosa MAP EXPLANATION 1979 Map, last accessed January, 2007 at http://www.seismo.ethz.ch/GSHAP/. 1911 CAYMAN TRENCH MIDDLE El Chichón Magnitude classes 1907 BELIZE Turneffe Is. Hayes, Gavin, and Wald, David, 2010, Slab models for subduction zones: U.S. Geological Survey Earthquake Hazards Acapulco , 4–5.9 Active volcanoes 1909 Program, last accessed July 22, 2010 at http://earthquake.usgs.gov/research/data/slab/. 1911 1957 Gulf of 6–6.4 Tuxtla Gutierrez 1928 Honduras Isla de Guanaja Mean slab depth 1928 Islas de la Bahia 6.5–6.9 1902 Isla de la Roatán NOAA National Geophysical Data Center, 2010, last accessed March 31, 2010 at http://www.ngdc.noaa.gov/hazards. 60 km 1999 1928 Isla de Utila AMERICA 60 7–7.4 100 1978 1931 Lightning Bank Siebert, Lee, and Simkin, Thomas, 2002, Volcanoes of the world—An illustrated catalog of Holocene volcanoes and their

GUATEMALA San Pedro , 7.5 200 A Sula Orozco F.Z. B' eruptions: Smithsonian Institution, Global Volcanism Program Digital Information series, GVP-3, last accessed Moctezuma Trough 1917 , 7.6 300 1976 15° 15° January 9, 2007 at http://www.volcano.si.edu/world/. 400 7.7 HONDURAS 500 E 1950 Cayos Miskitos Tarr, A.C., Villaseñor, Antonio, Furlong, K.P., Rhea, Susan, and Benz, H.M., 2010, Seismicity of the Earth 1900–2007: 7.8 A , 600 1902 Tegucigalpa EL SALVADOR U.S. Geological Survey Scientific Investigations Map 3064, scale 1:25,000,000. 7.9 S 1942 100 Plate boundaries e TRENCH T g B Subduction i d 8.0 R I. Providencia Albatross Transform P c 2001 (Colombia) e NICARAGUA 8.1 A p e Divergent t C n I. San Andreas Convergent u Golfo de Fonseca Plateau I a (Colombia) 8.2 h Seismic Hazard and Relative Plate Motion F e Managua Inferred T I. Del Mais Grande Depth of focus I 1992 Lago de C Nicaragua 110° 100° 90°

0–69 km R Z. Los 70–299 km F. Phoenix ec Angeles I tep 300–700 km S un eha San Dallas FIGURE EXPLANATION T 1950 Diego C l i p E COSTA RICA p e r t o n R i d g e Clark Basin El Paso 44 UNITED STATES Peak ground acceleration San Jose 0–0.2 m/s² 120° 110° 105° 100° 95° 90° 85° Austin Universal Transverse Mercator Projection 30° New Orleans 30° 0.2–0.4 Digital map database and cartography by Susan Rhea and Art Tarr San Houston Scale 1:8 000 000 Antonio 0.4–0.8 Manuscript approved for publication Nov. 16, 2011 Gulf of California Chihuahua 0 100 200 300 400 500 600 700 800 0.8–1.6 Kilometers BB-100 0 100 200 300 400 ' 1.6–3.2 . 46 3.2–6.4 DEPTH PROFILE EXPLANATION Distance (km) Magnitude classes Depth of focus 6.4–9.8 -100 0 100 200 300 400 500 600 TRENCH AXIS MEXICO 4–5.9 0–69 km AA' Monterrey TRENCH AXIS -200 -100 0 100 200 300 400 0 Relative plate motion 6–6.4 70–299 km Profiles of earthquake and volcano 47 NORTH AMERICA PLATE locations are constructed from the mapped 0 11.0–19.9 mm/yr 6.5–6.9 300–700 km G u l f o f M e x i c o data. Locations of the profile intersection TRENCH AXIS 20.0–39.9 7–7.4 Nucleation points -100 This and other USGS information products are available at -100 of M>8.3 events with the surface are drawn in the map and 0 http://store.usgs.gov/. 7.5 U.S. Geological Survey 40.0–59.9 labeled to coincide with the profile label. -200 PACIFIC OCEAN 7.6 Active volcanoes Box 25286, Denver Federal Center 17 Box defines extent of earthquakes Denver, CO 80225 58 Any use of trade, product or firm names is for 7.7 included in the profile. Length of the Merida -300 descriptive purposes only and does not imply Guadalajara 60.0–79.9 Earth structure -100 To learn about the USGS and its information products visit -200 profile graphic is the same as in the map. endorsement by the U.S. Government. 7.8 http://www.usgs.gov/. 20° Mexico 20° Air Distance in kilometers from the trench Depth (km) -400 73 City 1-888-ASK-USGS Although this information product, for the most part, PROFILE B Toluc a 7.9 Crust axis is indicated in the X direction, depth PROFILE A is in the public domain, it also contains copyrighted Puebla 80.0–100.0 This report is available at: 44 in kilometers is indicated in the Y -500 -200 materials as noted in the text. Permission to Upper mantle http://pubs.usgs.gov/of/2010/1083/f -300 Plate boundaries 8.0 direction. There is no vertical PROFILE X reproduce copyrighted items for other than personal Transition zone use must be secured from the copyright owner. exaggeration. See Explanation at side for -600 For more information concerning this publication, contact: PACIFIC PLATE BELIZE Subduction 8.1 Lower mantle Center Director, USGS Geologic Hazards Science Center RIVERA color key. Not all earth layers, earthquake -300 Box 25046, Mail Stop 966 Transform -700 Suggested citation: 59 depths or magnitude, are visible on every Denver, CO 80225 -400 MICROPLATE 8.2 Benz, H.M., Dart, R.L., Villaseñor, Antonio, Hayes, G.P., Tarr, GUATEMALA Divergent profile. (303) 273-8579 HONDURAS -800 A.C., Furlong, K.P., and Rhea, Susan, 2011, Seismicity of the Convergent Guatemala Tegucigalpa Earth 1900–2010 Mexico and vicinity: U.S. Geological COCOS PLATE City Or visit Geologic Hazards Science Center Web site at: Inferred http://geohazards.cr.usgs.gov/ Survey Open-File Report 2010–1083-F, scale 1:8,000,000. 110° 100° 90°