2010 Mentawai earthquake and tsunami

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2010 Mentawai earthquake
Shakemap October 2010 Indonesia.jpg
Indonesia Sumatra relief location map.jpg
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Indonesia relief location map.jpg
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UTC  time2010-10-25 14:42:22
ISC  event 15264887
USGS-ANSS ComCat
Local dateOctober 25, 2010 (2010-10-25)
Local time21:42:22
Magnitude7.8 Mw
Depth12.8 miles (20.6 km)
Epicenter 3°29′13″S100°04′55″E / 3.487°S 100.082°E / -3.487; 100.082 [1] [2]
Fault Sunda megathrust
Type Thrust fault
Areas affected Indonesia
Max. intensity V (Moderate) [1]
Casualties408 dead + 303 missing [3]

The 2010 Mentawai earthquake occurred with a moment magnitude of 7.8 [1] on 25 October off the western coast of Sumatra at 21:42 local time (14:42 UTC). [4] The earthquake occurred on the same fault that produced the 2004 Indian Ocean earthquake. It was widely felt across the provinces of Bengkulu and West Sumatra and resulted in a substantial localized tsunami that struck the Mentawai Islands. [5]

Contents

Tectonic setting

The island of Sumatra lies above the Sunda megathrust, the interface between the subducting Australian Plate and the overriding Sunda Plate. Movement on this structure has been responsible for many large historical megathrust earthquakes. The most recent sequence of large ruptures started with the 2004 Indian Ocean earthquake and included the 2005 Nias–Simeulue earthquake and the 2007 Sumatra earthquakes. [6] [7]

Earthquake

Map showing previous rupture areas close to the location of the October 2010 earthquake USGS Sunda Trench.JPG
Map showing previous rupture areas close to the location of the October 2010 earthquake

The earthquake occurred around 150 miles (240 km) west of Bengkulu, close to the Mentawai Islands, southwest of South Pagai. The USGS first reported the hypocenter of the quake at 20.5 miles (33.0 km) deep, [4] but later changed it to 8.8 miles (14.2 km) deep [8] and then 12.8 miles (20.6 km). The USGS also estimated the magnitude at 7.5 before revising the measurement to 7.8. [1] The intensity was MM IV in Bengkulu and MM III in Padang. [9]

The October 2010 earthquake is thought to have been a result of thrust faulting along or near the plate interface from the calculated focal mechanism and the focal depth. According to seismic hazard potentials and deformation features, the Sunda Trench can be divided into several segments. The southern segment lies to the south of Siberut Island. The rupture area of this earthquake is situated within the southern segment, where historical earthquakes include the earthquake of 1797 and the Mw ~ 9.0 1833 Sumatra earthquake. [1] [10]

Unlike in 2004, the tsunami caused by the October 2010 earthquake did not propagate westwards and other Indian Ocean nations were unaffected. It has been suggested that the tremor may have been a large aftershock of the much larger Sumatran earthquakes of September 2007. [11] The earthquake occurred around seven hours after the eruption of Mount Merapi on the Indonesian island of Java. However, the two events are not thought to be linked. [12]

Impact

Epicentre in relation to North and South Pagai October 2010 Sumatra Earthquake.png
Epicentre in relation to North and South Pagai

The earthquake's worst effects were felt on the remote Mentawai Islands. On the island of South Pagai, the tsunami reached a height of 3 m (9 ft) and swept as far as 600 m (1800 ft) inland. A maximum run-up of 16.86 m (55.3 ft) at Sibigau Island. [13] According to Indonesian officials, more than 20 villages were hit by the tsunami, displacing more than 20,000 people [12] and affecting about 4,000 households. The coastal village of Betu Monga on South Pagai was reported to have been destroyed with many residents still missing. [14] Many residents of the villages of Peurogat and Beleerakso were also reported to be missing. [12] Eighty percent of the houses in the North Pagai village of Muntei Baru were reported damaged or destroyed. [15]

According to a spokesperson for the Indonesian Agency for Meteorology, Climatology and Geophysics (BMKG), the quake was felt in several mainland towns, but no damage or deaths were reported. [16] The Mentawai Islands may have acted as a barrier, shielding the Sumatran coast by absorbing the brunt of the tsunami. [15] As of October 30, 2010, the confirmed death toll stands at 435, with 110 more unaccounted for. Many of the missing are believed to have been swept out to sea. [3]

Relief teams were initially unable to reach the islands due to poor weather conditions and rough seas. The Indonesian military was mobilized and international aid organizations also began a relief effort. [12] [14] The first aid began to arrive on October 27, two days after the earthquake and tsunami. [15]

Tsunami

Many villages on the islands were affected by the tsunami, which reached a height of 3 m (9 ft) and swept as far as 600 m (1800 ft) inland. The tsunami caused widespread destruction that displaced more than 20,000 people and affected about 4,000 households. 435 people were reported to have been killed, with over 100 more still missing. [3] The subsequent relief effort was hampered by bad weather [14] and the remoteness of the islands, which led to delays in the reporting of casualties. [17]

A tsunami run-up of 9.3 meters was recorded on the island of South Pagai. At least 75 people drowned when waves up to 5.5 meters swept the village Purorougat. [18] Located off South Pagai is Sibigau Island, where the maximum tsunami run-up height was 16.7 meters. The tsunami was also recorded in the southern part of Siberut, where it was at least 1 meter high. [19]

Aftershocks

Several aftershocks have been recorded since the initial quake, [20] the more significant of which are listed below.

Early warning system problems

The BMKG issued a tsunami warning based on seismographic data. [30] An alert was broadcast from radios and mosque loudspeakers on the mainland, prompting thousands to flee to higher ground. [11] It was later cancelled, but officials said that a tsunami warning system installed following the 2004 Indian Ocean earthquake and tsunami had failed to function properly. According to Indonesian officials, two of the system's buoys out at sea had been vandalized and were inoperative. [31] The claim of a breakdown was disputed by German officials who were working with the Indonesians to maintain and develop the system. Jörn Lauterjung, the head of the German-Indonesia Tsunami Early Warning Project, said that it had "worked very well", only one sensor had not been working and its failure had not harmed the system's operation. [32] However, the epicentre of the earthquake was so close to the islands that a warning would probably have been too late in any case, as the tsunami only took about five to ten minutes to reach Pagai. [14]

Response

See also

Related Research Articles

<span class="mw-page-title-main">Mentawai Islands Regency</span> Regency in West Sumatra, Indonesia

The Mentawai Islands Regency are a regency of West Sumatra Province which consists of a chain of about a hundred islands and islets approximately 150 kilometres off the western coast of Sumatra in Indonesia. They cover a land area of 6,033.76 km2 and had a population of 76,173 at the 2010 Census and 87,623 at the 2020 Census; the official estimate as at mid 2022 was 89,401 - comprising 46,431 males and 42,970 females. Siberut at 3,838.25 square kilometres is the largest of the islands. The other major islands are Sipura, North Pagai, and South Pagai. The islands lie off the Sumatran coast, across the Mentawai Strait. The indigenous inhabitants of the islands are known as the Mentawai people. The Mentawai Islands have become a noted destination for surfing, with over 40 boats offering surf charters to international guests.

<span class="mw-page-title-main">Simeulue Regency</span> Regency in Sumatra, Indonesia

Simeulue Regency is a regency in the Aceh special region of Indonesia. It occupies the whole island of Simeulue, 150 km off the west coast of Sumatra, with an area of 1,838.09 square kilometres. It had a population of 80,674 at the 2010 census and 92,865 at the 2020 census; the official estimate as at mid 2022 was 94,876.

<span class="mw-page-title-main">2005 Nias–Simeulue earthquake</span> 2005 earthquake in Sumatra, Indonesia

The 2005 Nias–Simeulue earthquake occurred on 28 March off the west coast of northern Sumatra, Indonesia. At least 915 people were killed, mostly on the island of Nias. The event caused panic in the region, which had already been devastated by the massive tsunami triggered by the 2004 Indian Ocean earthquake, but this earthquake generated a relatively small tsunami that caused limited damage. It was the third most powerful earthquake since 1965 in Indonesia.

<span class="mw-page-title-main">2006 Pangandaran earthquake and tsunami</span> Destructive tsunami earthquake south of Java Island

An earthquake occurred on July 17, 2006 at 15:19:27 local time along a subduction zone off the coast of west and central Java, a large and densely populated island in the Indonesian archipelago. The shock had a moment magnitude of 7.7 and a maximum perceived intensity of IV (Light) in Jakarta, the capital and largest city of Indonesia. There were no direct effects of the earthquake's shaking due to its low intensity, and the large loss of life from the event was due to the resulting tsunami, which inundated a 300 km (190 mi) portion of the Java coast that had been unaffected by the earlier 2004 Indian Ocean earthquake and tsunami that was off the coast of Sumatra. The July 2006 earthquake was also centered in the Indian Ocean, 180 kilometers (110 mi) from the coast of Java, and had a duration of more than three minutes.

<span class="mw-page-title-main">North Pagai</span> Island in West Sumatra, Indonesia

North Pagai is the smallest of the four principal Mentawai Islands off the west coast of Sumatra in Indonesia. It is south of Sipora and north of South Pagai Island.

<span class="mw-page-title-main">South Pagai</span> Island in West Sumatra, Indonesia

South Pagai is one of the Mentawai Islands of the west coast of Sumatra in Indonesia. The island is south of North Pagai Island. The population figure given for South Pagai refers to South Pagai District alone. The largely unpopulated south portion of Sikakap District covers the southern part of North Pagai Island and the northern part of South Pagai Island, as well as various small islands in the strait between the two.

<span class="mw-page-title-main">September 2007 Sumatra earthquakes</span> Earthquakes affecting Indonesia

The September 2007 Sumatra earthquakes were a series of megathrust earthquakes that struck the Sunda Trench off the coast of Sumatra, Indonesia, with three of magnitude 7 or greater. A series of tsunami bulletins was issued for the area. The most powerful of the series had a magnitude of 8.5, which makes it in the top 20 of the largest earthquakes ever recorded on a seismograph.

<span class="mw-page-title-main">Sunda megathrust</span> Geological feature

The Sunda megathrust is a fault that extends approximately 5,500 km (3300 mi) from Myanmar (Burma) in the north, running along the southwestern side of Sumatra, to the south of Java and Bali before terminating near Australia. It is a megathrust, located at a convergent plate boundary where it forms the interface between the overriding Eurasian plate and the subducting Indo-Australian plate. It is one of the most seismogenic structures on Earth, being responsible for many great and giant earthquakes, including the 2004 Indian Ocean earthquake and tsunami that killed over 227,000 people. The Sunda megathrust can be divided into the Andaman Megathrust, Sumatra(n) Megathrust and Java(n) Megathrust. The Bali-Sumbawa segment is much less active and therefore does not have the "megathrust" term associated with it.

<span class="mw-page-title-main">2010 Chile earthquake</span> Magnitude 8.8 earthquake in Chile on 27 February 2010

The 2010 Chile earthquake and tsunami occurred off the coast of central Chile on Saturday, 27 February at 03:34 local time, having a magnitude of 8.8 on the moment magnitude scale, with intense shaking lasting for about three minutes. It was felt strongly in six Chilean regions that together make up about 80 percent of the country's population. According to the United States Geological Survey (USGS) the cities experiencing the strongest shaking—VIII (Severe) on the Mercalli intensity scale (MM)—were Concepción, Arauco, and Coronel. According to Chile's Seismological Service, Concepción experienced the strongest shaking at MM IX (Violent). The earthquake was felt in the capital Santiago at MM VII or MM VIII. Tremors were felt in many Argentine cities, including Buenos Aires, Córdoba, Mendoza, and La Rioja. Tremors were felt as far north as the city of Ica in southern Peru.

<span class="mw-page-title-main">April 2010 Sumatra earthquake</span>

The April 2010 Sumatra earthquake occurred on April 7 at 5:15 AM local time with a moment magnitude of 7.8 and a maximum Mercalli intensity of V (Moderate). The shock occurred near the Banyak Islands, off the island of Sumatra in Indonesia. A tsunami watch was issued according to the Pacific Tsunami Warning Center in Honolulu which was later canceled. A 40 cm surge was reported in the Banyak Islands an hour after the quake, along with 62 injuries. Power outages were reported throughout the province of North Sumatra as well as in Aceh. This quake is one in a sequence of large earthquakes along the Sunda megathrust in the 2000s.

<span class="mw-page-title-main">Sikakap</span> Sub-district in West Sumatra, Indonesia

Sikakap is a sub-district on the Indonesian island of North Pagai, in the Mentawai Islands off Sumatra. The sub-district contains both Sikakap and Matobe, while Sikakap village incorporates the hamlets of Central Sikakap, East Sikakap and Sibaibai. Overall, the total population was 3,194 as of 2016. Also part of the sub-district is the Sikakap Strait between North and South Pagai, a designated Regional Marine Conservation Area. The Strait, an area of 3,960 hectares, has a coastal length of 19.79 kilometres (12.30 mi) and is a major contributor to West Sumatra's fishing industry.

The 2012 Indian Ocean earthquakes were magnitude 8.6 and 8.2 Mw  undersea earthquakes that struck near the Indonesian province of Aceh on 11 April at 15:38 local time. Initially, authorities feared that the initial earthquake would cause a tsunami and warnings were issued across the Indian Ocean; however, these warnings were subsequently cancelled. These were unusually strong intraplate earthquakes and the largest strike-slip earthquake ever recorded.

<span class="mw-page-title-main">2016 Sumatra earthquake</span> Earthquake off the coast of Sumatra, Indonesia

The 2016 Sumatra earthquake was a 7.8 magnitude earthquake which struck on 2 March 2016 in the Indian Ocean, approximately 800 kilometers southwest of Sumatra in Indonesia. Tsunami warnings were issued for Indonesia and Australia, but were withdrawn two hours later. There were no deaths directly related to the earthquake.

<span class="mw-page-title-main">2004 Alor earthquake</span> Earthquake in Indonesia

The 2004 Alor earthquake occurred on the island of Alor at 21:26:41 UTC on 11 November. Alor is an island located in Indonesia, the largest island of the Alor Archipelago with almost 16,800 residents. The earthquake had a magnitude of 7.5, on the moment magnitude scale, and an epicenter on Alor at a depth of 10 km (6.2 mi). It was recorded on 301 stations. The epicenter of the earthquake was located 1,600 km (990 mi) east of the capital of Jakarta. Hundreds of homes and much infrastructure was damaged with 23 deaths and thousands of casualties.

<span class="mw-page-title-main">2008 Simeulue earthquake</span> Earthquake in Indonesia

On February 20, 2008, an earthquake with a moment magnitude of 7.4 struck off the coast of Sumatra at a hypocentre depth of 26 km. The earthquake had an epicenter located on the island of Simeulue, northwest from Sinabang, a small town on the island. Three people were killed and an additional 25 seriously injured as a result of the earthquake.

<span class="mw-page-title-main">2021 Flores earthquake</span> Earthquake in Indonesia

An earthquake occurred 112 km, offshore, north of Maumere in the Flores Sea on December 14. The quake had a moment magnitude of 7.3 according to the United States Geological Survey (USGS). One person was killed and 173 others suffered injuries.

References

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  2. ↑ "Google Maps". maps.google.com. Google Maps. Retrieved 2010-10-27.
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  14. 1 2 3 4 "Indonesia tsunami: Death toll soars to 282". BBC News Online, 19:47 GMT, 27 October 2010.
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  19. ↑ Hill, Emma M.; Borrero, Jose C.; Huang, Zhenhua; Qiu, Qiang; Banerjee, Paramesh; Natawidjaja, Danny H.; Elosegui, Pedro; Fritz, Hermann M.; Suwargadi, Bambang W.; Pranantyo, Ignatius Ryan; Li, LinLin; Macpherson, Kenneth A.; Skanavis, Vassilis; Synolakis, Costas E.; Sieh, Kerry (2012). "The 2010 Mw 7.8 Mentawai earthquake: Very shallow source of a rare tsunami earthquake determined from tsunami field survey and near-field GPS data". Journal of Geophysical Research: Solid Earth. American Geophysical Union. 117 (B6). Bibcode:2012JGRB..117.6402H. doi:10.1029/2012JB009159. hdl: 10220/8666 .
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  27. ↑ "Magnitude 5.0 – SOUTHWEST OF SUMATRA, INDONESIA". earthquake.usgs.gov. USGS. 2010-10-26. Archived from the original on 2010-10-28. Retrieved 2010-10-27.
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  31. ↑ Indonesian tsunami warning system 'was not working'. Daily Telegraph, 6:13PM BST, 26 October 2010.
  32. ↑ "Indonesian Volcano Unleashes Biggest Blast Yet". NPR. 2010-10-28. Archived from the original on 2010-10-30. Retrieved 2013-10-11.
  33. ↑ "Toll Passes 270 in Indonesia Tsunami Disaster Archived 2010-10-30 at the Wayback Machine ". The Jakarta Globe, October 27, 2010
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  35. ↑ "Canada Offers Condolences Following Natural Disasters in Indonesia". Foreign Affairs Canada. 2010-10-27.
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  38. ↑ "Statement by the President on the Tsunami in Indonesia". Embassy of the United States Jakarta, Indonesia. 2010-10-26. Archived from the original on 2010-11-01. Retrieved 2010-10-27.
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