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Home , Antarctic Plate, Caribbean Plate, Chile Triple Junction, Cocos Plate, Nazca Plate, Nazca Ridge

U.S. DEPARTMENT OF THE INTERIOR OPEN-FILE REPORT 2015–1031-E U.S. GEOLOGICAL SURVEY This report supplements Open-File Report 2010–1083-E 80°W 70°W 60°W 50°W PRE-INSTRUMENTAL SEISMICITY 1500 – 1899 SAINT LUCIA Seismicity of the 1900–2013 Deaths, , MMI VIII+, or M 8 AND THE GRENADINES M 8.5 labeled with year ARUBA CURAÇAO Seismotectonics of ( Region) 80°W 60°W 40°W 11900900 A A' 1 1 1 2 0 200 400 600 800 1,000 1,200 BARBADOS Compiled by Gavin P. Hayes, Gregory M. Smoczyk, Harley M. Benz, Antonio Villaseñor, AND CURAÇAO Barranquilla Maracaibo Caracas HONDURAS GRENADA 3 Valencia Maracay Demerara Plain and Kevin P. Furlong Cartagena TRENCH AXIS Managua Barquisimeto NICARAGUA 19921992 0 2014 19501950 Clark Basin 10° PANAMA 1U.S. Geological Survey 2 GUYANA Institute of Earth Sciences, Consejo Superior de Investigaciones Científicas, (CSIC), Barcelona, Spain COSTA RICA Panama FRENCH 3Department of Geosciences, Pennsylvania State University, University Park, Pa., USA San Jose Cucuta VENEZUELA SURINAME GUIANA 10°N 11983983 PANAMA –200 Bucaramanga TECTONIC SUMMARY 19341934 GUYANA Equator The South American arc extends over 7,000 kilometers (km), from the Chilean margin offshore of southern , to Medellin Equator ECUADOR its intersection with the Panama zone, offshore of the southern coast of Panama in . It marks the plate –400 Manizales FRENCH boundary between the subducting Nazca plate and the South America plate, where the and lithosphere of the Nazca Bogota SURINAME PROFILE A plate begin their descent into the mantle beneath South America. The convergence associated with this process is Ibague GUIANA responsible for the uplift of the Mountains, and for the active volcanic chain present along much of this deformation front. Cocos Ridge 16191619 Cali Relative to a fixed South America plate, the Nazca plate moves slightly north of eastwards at a rate varying from approximately 80 COLOMBIA –600 millimeters/year (mm/yr) in the south, to approximately 65 mm/yr in the north. Although the rate of subduction varies little along BRAZIL the entire arc, there are complex changes in the geologic processes along the subduction zone that dramatically influence volcanic 16871687 17161716 activity, crustal deformation, generation and occurrence all along the western edge of South America. 19791979 15861586 1906 19581958 11513513 Most of the large in South America are constrained to shallow depths of 0–70 km as a result of both crustal and A Equator 18681868 11942942 11877877 interplate deformation. Crustal earthquakes are caused by deformation and mountain building in the overriding South America plate Quito 16041604 and generate earthquakes as deep as approximately 50 km. Interplate earthquakes occur due to slip along the dipping interface 11970970 AA'' Belem between the Nazca and the South America plates. Interplate earthquakes in this region are frequent and often large, and occur 20°S 20°S PARAGUAY between depths of approximately 10–60 km. Since 1900, numerous magnitude (M) 8 or larger earthquakes have occurred on this Equator ECUADOR Manaus Chile BB'Sao Luis subduction zone interface that were followed by devastating , including the 1960 M9.5 earthquake in southern Chile, the Guayaquil 19061906 0 200 400 600 800 1,000 1,200 11819819 largest instrumentally recorded earthquake in the world. Other notable shallow tsunami-generating earthquakes include the 1906 11921921 TRENCH AXIS M8.5 earthquake near Esmeraldas, Ecuador, the 1922 M8.5 earthquake near Coquimbo, Chile, the 2001 M8.4 Arequipa, Peru 19531953 0 earthquake, the 2007 M8.0 earthquake near Pisco, Peru, and the 2010 M8.8 Maule, Chile earthquake located just north of the 1960 event. 11730730 11822822 URUGUAY Piura 22005005 Large intermediate-depth earthquakes (those occurring between depths of approximately 70 and 300 km) are relatively limited in 90°W –200 ARGENTINA size and spatial extent in South America, and occur within the Nazca plate as a result of internal deformation within the subducting 11751751 plate. These earthquakes generally cluster beneath northern Chile and southwestern Bolivia, and to a lesser extent beneath northern 11960960 Chiclayo Peru and southern Ecuador, with depths from 110 to 130 km. Most of these earthquakes occur adjacent to the bend in the coastline BB'' 15751575 PERU-CHILE TRENCH between Peru and Chile. The most recent large intermediate-depth earthquake in this region was the 2005 M7.8 Tarapaca, Chile, Trujillo –400 11963963 11837837 earthquake. PROFILE B 19701970 PERU 40°S 40°S Earthquakes can also be generated to depths greater than 600 km as a result of continued internal deformation of the subducting 19961996 19471947 Nazca plate. Deep-focus earthquakes in South America are not observed from a depth range of approximately 300–500 km. Instead, –600 deep earthquakes in this region occur at depths of 500–650 km and are concentrated into two zones: one that runs beneath the 11966966 19401940 BRAZIL FALKLAND ISLANDS Peru-Brazil border and another that extends from central Bolivia to central Argentina. These earthquakes generally do not exhibit (ISLAS MALVINAS) MAP EXPLANATION Callao 11974974 large magnitudes. An exception to this was the 1994 Bolivian earthquake in northwestern Bolivia. This M8.2 earthquake occurred Magnitude 10°S Lima –800 at a depth of 631 km, which was until recently was the largest deep-focus earthquake instrumentally recorded (superseded in May 8.0 11994994 22007007 Cuzco 19631963 2013 by a M8.3 earthquake 610 km beneath the Sea of Okhotsk, Russia), and was felt widely throughout South and . 1837 8.5 19081908 Subduction of the Nazca plate is geometrically complex and influences the and seismicity of the western edge of South America. The intermediate-depth regions of the subducting Nazca plate can be segmented into five sections based on their angle of Peru Basin 11996996 Cuiaba 100°W 80°W 60°W 40°W 20°W 11942942 subduction beneath the South America plate. Three segments are characterized by steeply dipping subduction; the other two by 19601960 Brasilia 0200 400 600 800 1,000 near-horizontal subduction. The Nazca plate beneath northern Ecuador, southern Peru to northern Chile, and southern Chile 2001 11922922 La Paz MILES B Arequipa descend into the mantle at angles of 25° to 30°. In contrast, the slab beneath southern Ecuador to central Peru, and under central Goiania 0200 400 600 800 1,000 11913913 Cochabamba BOLIVIA KILOMETERS Chile, is subducting at a shallow angle of approximately 10° or less. In these regions of “flat-slab” subduction, the Nazca plate 22001001 Santa Cruz de La Sierra moves horizontally for several hundred kilometers before continuing its descent into the mantle, and is shadowed by an extended zone of crustal seismicity in the overlying South America plate. Although the South America plate exhibits a chain of active volcanism resulting from the subduction and partial melting of the Nazca oceanic lithosphere along most of the arc, these regions of inferred shallow subduction correlate with an absence of volcanic activity. 22005005 SEISMIC HAZARD AND RELATIVE PLATE MOTION 11959959 Campo Grande Belo Horizonte Pacific 11976976 100°W 80°W 60°W 40°W The of the triple junction in southern Chile (), are controlled by the interactions of the 20°S CAYMAN ISLANDS HAITI DOMINICAN REPUBLIC FIGURE EXPLANATION Antarctica, South America, and Scotia plates. Immediately south of the Chile triple junction, the Antarctica plate subducts beneath PERU-CHILE TRENCH JAMAICA VIRGIN 10% in 50 year peak ground ISLANDS, U.S. acceleration South America at a rate of approximately 16 mm/yr. There have been no moderate-to-large earthquakes associated with this CHILE 20°N 20°N 22007007 2 PARAGUAY PLATE 0−0.2 m/s convergence over the past century. Moving south and east through , plate motions between the South America and the HONDURAS SAINT LUCIA CURAÇAO 0.2−0.4 Scotia plates are predominantly left-lateral, at rates of 5–10 mm/yr. This plate boundary hosted two M7.8 earthquakes in December Chile Basin BARBADOS 20°S 11995995 Rio de Janeiro NICARAGUA 0.4−0.8 1949, near the Chile-Argentina border in . Farther south, the Antarctica plate moves towards the east with respect 11950950 Niteroi Sao Paulo 0.8−1.6 PANAMA TRINIDAD AND to the at rates of less than 10 mm/yr, decreasing towards the south. Several M6–6.5 earthquakes have been observed in TOBAGO 1.6−3.2 19871987 Santos the region over the past half-century, all with left-lateral strike-slip faulting mechanisms. Salta VENEZUELA 3.2−6.4 Asuncion GUYANA 6.4−9.8 FRENCH 11966966 Curitiba COLOMBIA SURINAME DATA SOURCES CC' 6655 mmm/yrm/yr GUIANA Relative plate motion –200 0 200 400 600 800 1,000 5588 mmm/yrm/yr 7−20 mm/yr 11983983 The earthquakes portrayed on the main map and the depth profiles are taken from two sources: (a) the Centennial earthquake TRENCH AXIS San Miguel De Tucuman 21−40 catalog (Engdahl and Villaseñor, 2002) and annual supplements for the interval 1900–2007, where the magnitude floor is 5.5 ECUADOR C 19181918 CC'' Santos Equator 41−60 globally, and (b) a catalog of earthquakes having high-quality depth determinations for the period 1964–2002 and a magnitude Equator Plateau range of 5.0–5.4 (Engdahl, written commun., 2003) 0 61−80 1922 Sala y Gomez Ridge SOUTH AMERICA 19181918 The nucleation points of great earthquakes larger than M8.3 are designated with a label showing the year of occurrence. Their 6655 mm/yrmm/yr PLATE 81−110 rupture areas are shown as light gray polygons. Major earthquakes (M7.5–8.2) are labeled with the year of occurrence, whereas PERU –200 Porto Alegre Plate boundaries earthquakes (M8.0–8.2) are labeled with the year of occurrence and also denoted by a white outline (Tarr and others, 2010). 19431943 BRAZIL Subduction 19771977 Cordoba 30°S Transform The Seismic Hazard and Relative Plate Motion panel displays the generalized seismic hazard of the region (Giardini and others, Santa Fe Divergent PROFILE C Others 1999) and representative relative plate motion vectors using the NUVEL-1A model (DeMets and others, 1994.) –400 19711971 7711 mmm/yrm/yr Rosario BOLIVIA Pre-instrumental seismicity was obtained from the National Oceanic and Atmospheric Administration (NOAA) National Geophysi- 11906906 11985985 URUGUAY cal Data Center (2010) database of significant earthquakes; locations are approximate, based on macro-seismic reports and field -30° Valparaiso Santiago 40°W investigations. We selected earthquakes with associated reports of moderate to major damage, deaths, estimated magnitude of VIII –600 Buenos Aires or greater (if known), Modified Mercalli Intensities VIII or greater, or tsunami generation. Base map data sources include GEBCO La Plata Montevideo NAZCA PLATE PARAGUAY 2008, Volcanoes of the World dataset (Siebert and Simkin, 2002), plate boundaries (Bird, 2003), Digital Chart of the World (1992), 11914914 11928928 20°S 20°S and Esri (2002). Slab contours are from Hayes and others (2012). ARGENTINA 7733 mmm/yrm/yr 2010 19391939 REFERENCES Concepcion 11953953 Bird, Peter, 2003, An updated digital model of plate boundaries: Geochemistry, , Geosystems, v. 4, no. 3, 52 p., doi: 11960960 19621962 10.1029/2001GC000252. D 11975975 MAP EXPLANATION URUGUAY 11960960 ARGENTINA DeMets, Charles, Gordon, R.G., Argus, D.F., and Stein, Seth, 1994, Effects of recent revisions to the geomagnetic reversal time scale DD'' CHILE on estimates of current plate motions: Geophysical Research Letters, v. 21, no. 20, p. 2191–2194. 1960 Digital Chart of the World, 1992: http://earth-info.nga.mil/publications/specs/printed/89009/89009_DCW.pdf, last accessed Magnitude classes 1960 March 9, 1996. 5.5–5.7 Nucleation points and 7744 mmm/yrm/yr in year of occurrence Engdahl, E.R., and Villaseñor, Antonio, 2002, Global seismicity 1900–1999, Lee, W.H.K., Kanamori, Hiroo, Jennings, P.C., and 5.7–6.0 Kisslinger, Carl, eds., International Handbook of Earthquake and Engineering : International Association for Active volcanoes 40°S Earthquake Engineering, v. 81(A), chap. 41, p. 1–26. 6.0–6.3 5511 mmm/yrm/yr Esri, 2002, Esri data and maps: Redlands, Calif., Environmental Systems Research Institute (Esri). [Also available at 6.3–6.6 Mean slab depth http://www.esri.com/data/data-maps/index.html.] Arabian 40°S 40°S 6.6–6.9 60 km GEBCO, 2008, The EBCO_08_Grid, ver. 20091120: UNESCO, General Bathymetric Chart of the , UNESCO, accessed Jan. 8, Basin 100 2010 at http:/www.gebco.net/. 6.9–7.1 200 40°S Giardini, Domenico, Grünthal, Gottfried, Shedlock, K.M., Zhang, Peizhen, and Global Seismic Hazards Program, 1999: Global 300 FALKLAND ISLANDS 100°W 7.1–7.4 400 (ISLAS MALVINAS) seismic hazards map, accessed February 18, 2014, at http://www.seismo.ethz.ch/static/GSHAP/. 500 Hayes, G.P., Wald, D.J, and Johnson, R.L., 2012, Slab 1.0—A three-dimensional model of global subduction zone geometrics: Journal 7.4–7.7 600 of Geophysical Research, v. 117, doi: 10.1029/2011JB008524. 7.7–8.0 Plate boundaries PLATE National Oceanic and Atmospheric Administration (NOAA), 2010, National Geophysical data center: National Oceanic and SCOTIA PLATE Atmopheric Administration, accessed March 31, 2010, at http://www.ngdc.noaa.gov/hazard/hazards.shtml. Greater than Subduction 8.0 Transform Siebert, Lee, and Simkin, Thomas, 2002, Volcanoes of the world—An illustrated catalog of Holocene volcanoes and their eruptions: 120°W 100°W 80°W 60°W 40°W 20°W Chile Triple Junction Divergent Smithsonian Institution, Global Volcanism, Program Digital Information series, GVP–3, last accessed Jan. 9, 2007, at Depth of focus DD' Inferred 0200 400 600 800 1,000 http://www.volcano.si.edu/world/. –200 0 200 400 600 (! Less than 69 km Country MILES Tarr, A.C., Villaseñor, Antonio, Furlong, K.P., Rhea, Susan, and Benz, H.M., 2010, Seismicity of the Earth 1900–2007: U.S. (! Boundary TRENCH AXIS 70–299 km 0200 400 600 800 1,000 Geological Survey Scientific Investigations Map 3064, scale 1:25,000,000. [Available at http://pubs.usgs.gov/sim/3064/.] KILOMETERS (! Greater than 300 km 1911 8.0-8.2 Magnitude earthquake location FALKLAND ISLANDS zones* 0 1935 7.5-8.2 Magnitude (ISLAS MALVINAS) Falkand earthquake location Rupture zones* Plateau 50°S DEPTH PROFILE EXPLANATION Distance (km) *Aftershock zones for large earthquakes represent the area over XX'–200 which significant aftershock activity was observed in the immediate Magnitude classes –200 0 200 400 vicinity of the main shock, within tectonic environments coupled to This and other USGS information products are available at Publishing support provided by: Depth of focus Profiles of earthquake and locations PROFILE D the main shock system. For example, for the 2011 M 9.0 Tohoku http://store.usgs.gov/ Denver Publishing Service Center Less than 6.0 (! 11949949 earthquake, extensive occurred on the interplate thrust U.S. Geological Survey 6.0–6.5 Less than 69 km are constructed from the mapped data. Manuscript approved for publication February 11, 2015 Tierra del Fuego contact between the Pacific and North America plates, as well as in Box 25286, Denver Federal Center 6.5–7.0 (! 70–299 km Locations of the profile intersection with the TRENCH AXIS the overlying upper plate, and on faults within the Any use of trade, firm, or product names is for descriptive 7.0–7.5 (! surface are drawn in the map and labeled to -50° Denver, CO 80225 Greater than 300 km –400 outboard of the subduction zone. We do not include more distant purposes only and does not imply endorsement by the U.S. 7.5 0 coincide with the profile label. Box defines triggered aftershocks such as those that occurred on upper plate To learn about the USGS and its information products visit Government. 7.6 Nucleation point extent of earthquakes included in the profile. >! faults within mainland Japan. http://www.usgs.gov/. Although this information product, for the most part, is in Length of the profile graphic is the same as 1-888-ASK-USGS 7.7 Drake Passage the public domain, it also contains copyrighted materials as Active volcanoes in the map. Distance in kilometers from the noted in the text. Permission to reproduce copyrighted 7.8 This report is available at: trench axis is indicated in the Y direction. 100°W 90°W 80°W 70°W 60°W 50°W 40°W MAP LOCATION http://pubs.usgs.gov/of/2015/1031/e items must be secured from the copyright owner. Earth structure 7.9 There is no vertical exaggeration. See –200 South America Albers Equal Area Projection Scale 1:14,000,000

Depth (km) Suggested citation: Air explanation at side for color key. Not all Digital map database and cartography by Greg Smoczyk For more information concerning this publication, contact: Hayes, G.P., Smoczyk, G.M., Benz, H.M., Villaseñor, Antonio, 8.0 Crust Earth layers and earthquake depths or SCALE 1:14,000,000 Center Director, USGS Geologic Hazards Science Center and Furlong, K.P., 2015, Seismicity of the Earth 1900–2013, Upper mantle Box 25046, Mail Stop 966 magnitude are visible on every profile. Seismotectonics of South America (Nazca Plate Region): 8.1 Denver, CO 80225 Transition zone 0200 400 600 800 1,000 U.S. Geological Survey Open-File Report 2015–1031-E, 1 sheet, PROFILE X MILES (303) 273-8579 Greater then Lower mantle –400 scale 1:14,000,000 http://dx.doi.org/10.3133/of20151031E. or equal to 8.2 Or visit Geologic Hazards Science Center Web site at: 0200 400 600 800 1,000 http://geohazards.cr.usgs.gov/ ISSN 2331-1258 (online) KILOMETERS http://dx.doi.org/10.3133/of20141031E