Phnom

Penh

Ho Chi

Minh City

B

B'

C

C'

2004

2005

2007

2012

D

D'

A

A'

L aos

Gulf of Thailand

Dao Phu Quoc

BURMA

(MYANMAR)

THAILAND

MALAYSIA

88° 92° 96° 100° 104° 108°

14°

88° 92° 96° 100° 104° 108°

10°

6°

2°

2°S

6°S

10°S

14°

10°

6°

2°

2°S

6°S

10°S

EQUATOR EQUATOR

Mergui

Archipelago

Andaman Islands

(India)

Bangkok

Andaman Sea

South China Sea

Ipoh

Kuala

Lumpur

Singapore

Langkawi

Kepulauan

Lingga

Kepulauan

Anambas

Kepulauan

Natuna Besar

Kepulauan

Rian

Nicobar Islands

(India)

Great Nicobar Is.

(India)

Banda

Aceh

Banka

Belitang

Palembang

INDONESIA

Java Sea

Sumatra

Medan

IND IAN OCEA N

Simeulue Is.

(Indonesia)

Nias

Tanahmasa

Tanahbasa

Siberut

Sipura

Pagai Utara

Paga Selatan

Padang

SUMATRA

FAULT

Enggano

Java

Jakarta

Bandung

TanjungkarangTelukbetung

SUNDA-JAVA TRENCH

INVESTIGATOR RIDGE

NINETY EAST RIDGE

INDO-AUSTRALIA PLATE

SUNDA PLATE

ANDAMAN

FAULT

SYSTE

SAGAING FAULT

M

Rangoon

Andaman

Basin

Batu Islands

Mentawai

Islands

SUNDA-JAVA TRENCH

Krakatau

M ≥ 4.5, Outboard of trench

M ≥ 4.5, Inboard of trench

M ≥ 8.0

Distance Along Section (km)

0 1,000 2,000 3,000

1980

1990

2000

2010

12°S

10°S 

8°S

6°S

4°S

16° 14° 12° 10° 8° 6° 4° 2° 0° 2°S

94°

94° 96° 98° 100° 102°

92°

92°

90°

90°

88°

88°

86°

86°

84°

84°

Time-Space Plot of Seismicity in the Sumatra Arc

1973–2011

N

DEPTH PROFILE EXPLANATION

Profiles of earthquake and volcano 

locations are constructed from the 

mapped data. Locations of the profile 

intersections with the surface are drawn 

in the map and labeled to coincide with 

the profile label. Box defines extent of 

earthquakes included in the profile. 

Length of the profile graphic is the same 

as in the map. Distance in kilometers 

from the trench axis is indicated in the 

X direction, depth in kilometers is 

indicated in the Y direction. There is no 

vertical exaggeration. See Explanation 

at side for color key. Not all earth 

layers, earthquake depths or 

magnitudes, are visible in every profile.

Earth structure

Air

Crust

Upper mantle

Transition zone

Lower mantle

Depth of focus

0–69 km

70–299 km

300–700 km

Magnitude classes

4.0–4.4

4.5–4.9

5.0–5.4

5.5–5.9

6.0–6.4

6.5–6.9

7.0–7.4

7.5–7.9

8.0–8.4

8.5–8.9

≥9.0

Nucleation points

of M>8.3 events

Active volcanoes

Distance (km)

TRENCH AXIS

Depth (km)

PROFILE X

100

0

-100

-200

-300

-400

-500

-600

-700

-800

-900

-1,000

-300 -100 100 0 300 500

5 6

6 0

6 4

6 8

4 4

4 4

4 5

Seismic Hazard and Relative Plate Motion 90°E 95°E 100°E 105°E 110°E

15°

10°

5°

0°

5°S

10°S

SUNDA PLATE

INDO-AUSTRALIA PLATE

Jakarta

Bandung Semarang

Singapore

Medan

Ho Chi Minh

City

Bangkok

Rangoon

4 4

5 6

FIGURE EXPLANATION

Plate boundaries

Subduction

Transform

Divergent

Others

Peak ground acceleration

0–0.2 m/s2

0.2–0.4

0.4–0.8

0.8–1.6

1.6–3.2

3.2–6.4

6.4–9.8

India:Sunda

Australia:Sunda

Relative plate motion (mm/yr)

D D 0

0

PROFILE D

-200

-200

-300

-400

-500

-600

-700

-100

-100

100 200 300 400 500

C C’

PROFILE C

TRENCH AXIS

-100 100 200 0 300 400

0

-200

-300

-400

-500

-600

-100

TRENCH AXIS

PROFILE B

-200 100 200 -100 0 300 400

0

-200

-300

-100

B B’

TRENCH AXIS

PROFILE A

A A’ -100 0 100 200 300 400

0

-200

-300

-100

100 0 100 200 300 400 500 600 700 KILOMETERS

SCALE 1: 6 000 000

100 0 100 200 300 400 500 MILES

Pre-Instrumental Seismicity 1500–1899

M ≥ 8.0, tsunami, or deaths

1881

1861

1797

1833

Magnitude

Historic rupture zones

< 8.0

8.0–8.5

95°E 100°E 105°E

5°

0°

5°S

10°S

0–69 km

70–299 km

300–700 km

Inferred

Subduction

Transform

Divergent

MAP EXPLANATION

Magnitude classes

Plate boundaries

4.0–4.4

4.5–4.9

5.0–5.4

5.5–5.9

6.0–6.4

6.5–6.9

7.0–7.4

7.5–7.9

8.0–8.4

8.5–8.9

≥9.0

Depth of focus

Mean slab depth (km)

Nucleation points

Aftershock zones

Active volcanoes

60

100

200

300

400

500

600

Country 

Boundary

U.S. Department of the Interior

U.S. Geological Survey

Seismicity of the Earth 1900–2012

Sumatra and Vicinity

Compiled by Gavin P. Hayes,1 Melissa Bernardino,2 Fransiska Dannemann,3 Gregory Smoczyk,1 Richard Briggs,1 Harley M. Benz,1 Kevin P. Furlong, and Antonio Villaseñor 4 5

1U.S. Geological Survey

2Department of Geological Sciences, University of Colorado Boulder, Colo., USA

3Department of Geological Sciences, Indiana University, Bloomington, Ind., USA

4Department of Geosciences, Pennsylvania State University, State College, Penn., USA

5Institute of Earth Sciences, Consejo Superior de Investigaciones Científicas, (CSIC), Barcelona, Spain

2013

TECTONIC SUMMARY

The plate boundary southwest of Sumatra, Indonesia, is part of a long tectonic collision zone that extends over 

8,000 km from Papua, New Guinea, in the east, to the Himalayan front in the west. The Sumatra-Andaman part of the 

collision zone forms a subduction-zone megathrust boundary, the Sunda Arc (Sunda-Java trench), which accommodates 

convergence between the Indo-Australia and Sunda plates. This convergence is responsible for the intense seismicity 

and volcanism in Sumatra. Plate-boundary related deformation is also not restricted to the subduction zone and 

overriding plate; the subducting Indo-Australia plate actually comprises two somewhat independent plates (India plate 

and Australia plate), with small amounts of motion relative to one another, that are joined along a broad, actively 

deforming region producing seismicity up to several hundred kilometers west of the trench. This deformation is 

exemplified by the recent April 2012 earthquake sequence, which includes the April 11, 2012 M 8.6, and M 8.2 

strike-slip events and their subsequent aftershocks.

The relative motion between the Indo-Australia and Sunda plates is rapid, decreasing from roughly 63 mm/yr near 

the southern tip of Sumatra (Australia plate relative to Sunda plate) to 44 mm/yr north of Andaman Islands (India 

relative to Sunda) and rotating counterclockwise to the northwest, so that relative motion near Jakarta is nearly 

trench-normal but becomes nearly trench parallel near Burma. As a result of the rotation of relative plate motion along 

the strike of the arc and the interaction of multiple tectonic plates, several interrelated tectonic elements compose the 

Sumatra-Andaman part of the plate boundary. Most strain accumulation and release occurs along the Sunda megathrust 

of the main subduction zone, where lithosphere of the subducting Indo-Australia plate is in contact with the overlying 

Sunda plate down to a depth of 60 km. Strain release associated with deformation within the subducting slab is 

evidenced by deeper earthquakes that extend to depths of less than 300 km on Sumatra and 150 km or less along the 

Andaman Islands. The increasingly oblique convergence between these two plates moving northwest along the arc is 

accommodated by crustal seismicity along a series of transform and normal faults. The Sumatra Fault, a major 

transform structure that bisects Sumatra, accommodates the northwest-increasing lateral component of relative plate 

motion. East of the Andaman Islands, back-arc spreading in the Andaman Sea produces a zone of distributed normal 

and strike-slip faulting. Similar to the Sumatra Fault, the Sagaing Fault near Burma also accommodates the strike-slip 

component of oblique plate motion. 

Paleoseismic studies using coral reefs as a proxy for relative land level changes associated with earthquake 

displacement suggest that the Sunda arc has repeatedly ruptured during relatively large events in the past, with records 

extending as far back as the 10th century. In northern Simeulue Island, the southern terminus of the 2004 megathrust 

earthquake rupture area, a cluster of megathrust earthquakes occurred over a 56-year period between A.D. 1390 and 

1455 resulting in uplift substantially greater than that caused by the 2004 event. Studies that look at large sheeted 

deposits of sand on land interpreted as the transport of debris from a tsunami wave also indicate that this region has 

gone through significant tsunamis in the past, albeit infrequently.

Prior to 2004, the most recent megathrust earthquakes along the Sunda Arc were in 1797 (M 8.7–8.9), 1833 (M 

8.9–9.1), and 1861 (M 8.5). Since 2004, much of the Sunda megathrust between the northern Andaman Islands and 

Enggano Island, a distance of more than 2,000 km, has ruptured in a series of large subduction zone earthquakes—most 

rupturing the plate boundary south of Banda Aceh. The great M 9.1 earthquake of December 26, 2004, which produced 

a devastating tsunami, ruptured much of the boundary between Burma and Simeulue Island offshore Banda Aceh. 

Immediately to the south of the great 2004 earthquake, the M 8.6 Nias Island earthquake of March 28, 2005, ruptured a 

400-km section between Simeulue and Batu Islands. Farther south in the Mentawai Islands, two earthquakes on 

September 12, 2007 of M 8.5 and M 7.9 occurred in the southern portion of the estimated 1797 and 1833 rupture zone, 

which extends from approximately Enggano Island to the northern portion of Siberut Island. Smaller earthquakes have 

also been locally important: a M 7.6 rupture within the subducting plate caused considerable damage in Padang in 

2009, and a M 7.8 rupture on October 25, 2010, occurred on the shallow portion of the megathrust to the west of the 

Mentawai Islands, and caused a substantial tsunami on the west coast of those islands.

In addition to the current seismic hazards along this portion of the Sunda arc, this region is also recognized as 

having one of the highest volcanic activity levels in the world. One of the most dramatic eruptions in human history 

was the Krakatau eruption on August 27–27, 1883, a volcano just to the southeast of the island of Sumatra, which 

resulted in over 35,000 casualties.

Subduction and seismicity along the plate boundary adjacent to Java is fundamentally different from that of the 

Sumatran-Andaman section. Relative motion along the Java arc is trench-normal (approximately 65–70 mm/yr) and 

does not exhibit the same strain partitioning and back-arc strike-slip faulting that are observed along the Sumatra 

margin. Neither has the Java subduction zone hosted similar large magnitude megathrust events to those of its neighbor, 

at least in documented history. Although this region is not as seismically active as the Sumatra region, the Java arc has 

hosted low-to intermediate-magnitude extensional earthquakes and deep-focus (300–700 km) events and exhibits a 

similar if not higher volcanic hazard. This part of the arc has also hosted two large, shallow tsunami earthquakes in the 

recent past which resulted in high tsunami run-ups along the southern Java coast.

DATA SOURCES

The earthquakes portrayed on the main map (above) are taken from two sources: (1) the Centennial earthquake 

catalog (Engdahl and Villaseñor, 2002), and annual supplements for the interval 1900–2007, where the magnitude 

floor is 5.5 globally, and (2) the NEIC PDE Catalog M4.0 and larger from 1973 to July 19, 2012.

1900–2001 Centennial catalog M=5.5–9.5(Engdahl and Villaseñor, 2002)

2002–2012 NEIC catalog M=5.5–9.2

1964–2001 EHDB catalog M=4.0–5.4 (Engdahl, written commun.)

2002–2012 NEIC catalog M<5.5 

The nucleation points of great earthquakes (M≥8.3) are designated with a label showing the year of occurrence. 

Their rupture areas are shown as pale reddish polygons. 

The Seismic Hazard and Relative Plate Motion panel displays the generalized seismic hazard of the region 

(Giardini and others, 1999) and representative relative plate-motion vectors using the Morvel model (DeMets and 

others, 2010).

Pre-instrumental seismicity was obtained from the NOAA National Geeophysical Data Center (2010) database of 

significant earthquakes; locations are approximate, based on macro-seismic reports and field investigations. We 

selected earthquakes with associated reports of moderate to major damage, 10 or more deaths, a estimated magnitude 

of 7.5 or greater (if known), Modified Mercalli Intensities X, or tsunami generation.

Base map data sources include GEBCO 2008 shaded relief, Volcanoes of the World dataset (Siebert and Simkin, 

2002), plate boundaries (Bird, 2003), and geographic information from Digital Chart of the World (1992), and ESRI 

(2002). Slab contours are from Hayes and Wald (2010).

REFERENCES

Abercrombie, R.E., Antoloi, M., Felzer, K., and Ekström, G., 2001, The 1994 Java tsunami earthquake—Slip over a 

subducting seamount: Journal of Geophysical Research, v. 106, p. 6595—6607.

Ammon, C.J., Kanamori, Hiroo, Lay, T., and Velasco, A.A., 2006, The 17 July Java tsunamic earthquake: Geophysical 

Research Letters, 33, L24308, doi: 10.1029/2006GL028005.

Bird, Peter, 2003, An updated digital model of plate boundaries: Geochemistry Geophysics Geosystems, v. 4, no. 3, 52 

p.

DeMets, Charles, Gordon, R.G., and Argus, D.F., 2010, Geologically current plate motions: Geophysical Journal 

International, v. 181, p. 1—80, doi: 10.1111/j.1365-246X.2009.04491.x.

Digital Chart of the World, 1992: Accessed March 9, 1996, at 

http://earth-info.nga.mil/publications/specs/printed/89009/89009_DCW.pdf.

Engdahl, E.R., and Villaseñor, Antonio, 2002, Global seismicity 1900‒1999, in Lee, W.H.K., Kanamori, Hiroo, Jennings, 

P.C., and Kisslinger, Carl, eds., International Handbook of Earthquake and Engineering Seismology, v. 81(A), chap. 

41, p. 1‒26.

ESRI, 2002, ESRI data and maps: Redlands, Calif., ESRI, http://www.esri.com/data/data-maps.

GEBCO, 2008, The GEBCO_08_Grid, ver. 20091120: GEBCO. Accessed July 5, 2012, at http://www.gebco.net.

Giardini, Domenico, Grünthal, Gottfried, Shedlock, K.M., Zhang, Peizhen, and Global Seismic Hazards Program, 

1999, Global Seismic Hazards Map: Accessed on Jan. 9, 2007, at http://www.seismo.ethz.ch/static/GSHAP/.

Hayes, Gavin, and Wald, David, 2010, Slab models for subduction zones: U.S. Geological Survey Earthquake Hazards 

Program. Accessed on Feb. 23, 2010 at http://earthquake.usgs.gov/research/data/slab.

Malod, J.A., Karta, K., Beslier, M.O., and Zen, M.T., Jr., 1995, From normal to oblique subduction—Tectonic 

relationships between Java and Sumatra: Journal of Southeast Asian earth Sciences, v. 12, p. 85–93. 

National Oceanic and Atmospheric Administration (NOAA), 2010: National Geophysical data Center (NGDC): 

National Oceanic and Atmospheric Administration. Accessed on Mar. 31, 2010, at 

http://www.ngdc.noaa.gov/ngdc.html.

Siebert, Lee, and Simkin, Thomas, 2002, Volcanoes of the world—An illustrated catalog of Holocene volcanoes and their 

eruptions: Smithsonian Institution, Global Volcanism Program Digital Information Series, GVP-3. Accessed on Jan. 

9, 2007, at http://www.volcano.si.edu/world.

Spence, W., 1986, The 1977 Sumba earthquake series—Evidence for slab pull force acting at a subduction zone: 

Journal of Geophysical Research, v. 91, no. 87, p. 7225–7239.

Tarr, A.C., Villaseñor, Antonio, Furlong, K.P., Rhea, Susan, and Benz, H.M., 2010, Seismicity of the Earth 1900–2007: 

U.S. Geological Survey Scientific Investigations Map 3064, scale 1:25,000,000.

Open-File Report 2010–1083-L

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Mercator projection

Suggested citation:

Hayes, G.P., Bernardino, Melissa, Dannemann, Fransiska, Smoczyk, 

Gregory, Briggs, Richard, Benz, H.M., Furlong, K.P., and Villaseñor, 

Antonio, 2013, Seismicity of the Earth 1900–2012 Sumatra and vicinity: 

U.S. Geological Survey Open-File Report 2010–1083-L, scale 1:6,000,000, 

http://pubs.usgs.gov/of/2010/1083/l/ 

0 250 500 750 KILOMETERS

0 250 500 750 KILOMETERS