2011 Tarlay earthquake explained

2011 Tarlay earthquake
Timestamp:2011-03-24 13:55:13
Isc-Event:16357310
Anss-Url:usp000hyfx
Local-Time:20:25:13 (UTC+06:30)
Magnitude:6.8
Depth:10km (10miles)
Countries Affected:Myanmar, Thailand, Laos, China
Casualties:75–151 killed, 212 injured
Intensity:[1]

The 2011 Tarlay earthquake occurred on 24 March in Shan State, Myanmar. The earthquake measured 6.8 and had an epicenter northwest of the border between Myanmar, Thailand and Laos. It occurred in a region accommodating tectonic deformation brought by the collision between the Indo-Australian and Eurasian plates. Strike-slip faulting along the Nan Ma Fault was identified as the cause. There were between 75 and 151 fatalities; including one death in Thailand. An additional 212 people were injured. Hundreds of buildings and some transport infrastructure were damaged in Myanmar and Thailand.[2] In the aftermath of the disaster, the Burmese government provided aid and relief supplies to the affected region. Neighbouring countries China, India and Thailand provided monetary assistance. Several international humanitarian organizations also supported in the relief and recovery.

Tectonic setting

See also: Geology of Myanmar. Myanmar lies at the junction of the Alpine–Himalayan Orogenic Belt and Indonesian Island Arc System. In northern Myanmar, continental collision is ongoing between the northward moving Indian Plate and the Eurasian Plate. Collision also occurs along the Indo-Burman Ranges (Patkai, Naga and Chin Hills) and Arakan Mountains of western Myanmar.[3] In this zone of highly oblique collision, most of the motion is accommodated by the north-south trending Sagaing Fault, a major right-lateral strike-slip fault that runs through the western and central part of Myanmar. Additional deformation is distributed and accommodated within eastern Myanmar and Thailand extending into Laos. Deformation within the Shan Plateau is partly accommodated by a set of southwest-northeast trending left-lateral strike-slip faults. Major faults in the Shan Plateau include the Mae Chan, Nam Ma, Menxing, Menglian, Nantinghe, Wanding, and Longling faults.[4] The faults closest to the epicenter are the Mae Chan and Nam Ma faults, about east of the Sagaing Fault.[5] [6]

Earthquake

The 6.8 earthquake occurred with a focal depth of and epicenter north-northwest of Tachilek, Shan State; north of the Golden Triangle region. It was one of the largest earthquake recorded in the area. A focal mechanism solution obtained for the earthquake indicated left-lateral slip along a vertical fault plane. Large earthquakes also struck the area in 1988 (7.0) and 1995 (6.8).[7]

Geology

The northeast-southwest trending Nan Ma Fault runs through Myanmar, northern Laos and China for a length of . Geomorphic studies along the central section of the fault where the Mekong River crosses it suggest it was previously a right-lateral fault. It produced up to of right-lateral displacement between 5 and 20 million years ago.[8] The fault reactivated as a left-lateral fault and its average slip rate is estimated at per year. The fault branches from a single structure into multiple subparallel splay segments at its westernmost end. The earthquake ruptured one of these segments at the westernmost Nan Ma Fault.

Surface rupture

The mainshock produced a long surface rupture along the westernmost segment of the Nam Ma Fault. The surface offset peaked at almost . Based on inferring InSAR data, the coseismic slip along the fault rupture was concentrated within the shallow of the crust. The maximum slip was estimated at at depths of . Clear surface faulting was observed on farmland; at the paddy fields southeast of the epicenter, of surface rupture was mapped. The measured offset ranged between and with an average of . In Tarlay, offsets were in the order of several tens of centimetres.

Ground motion

See also: Spectral acceleration. The earthquake was associated with 24 seconds of significant ground motion. Resonance may have occurred in the frequency range of 1.82–2.1, affecting many low to medium-rise buildings. The horizontal ground motion was the primary cause of building destruction during the earthquake.[9] The highest peak ground acceleration, 0.20 g, was instrumentally measured south of the epicenter in Mae Sai, Thailand. This measurement was the highest ever recorded in Thailand from an earthquake.[10] Damage in Tarlay corresponded to a Modified Mercalli intensity (MMI) of VIII (Severe), while damage to a road about from the epicenter was given MMI X (Extreme).[1]

Impact

The death toll in Myanmar stood at 74 to 150;[11] [12] 212 people were injured;[13] 3,152 made homeless; and 18,000 were affected. At least 413 buildings were damaged and one bridge collapsed in Shan State. Around 90 villages were moderately or heavily damaged; in 50 of those villages, more than half the building stock were damaged or destroyed. In 40 other villages, damage was more than 30 percent of all buildings.[14] At least 40 people died and 50 others were injured in Tarlay; one hospital collapsed in the town.[15] Ground subsidence of was observed at a bridge between Kengtung and Tachileik. In Tachileik, two people died and six were injured.[16] Twenty-five people died and 57 were injured when a Baptist church collapsed during a service in Kyakuni village.[17] In Monglin, at least 128 homes were razed.[18] Fourteen Buddhist monasteries and nine government infrastructure were damaged.[19]

In Mae Sai, Thailand, one person died when a wall collapsed. Sixteen people, including seven Burmese and five Chinese nationals were also injured. Buildings in the district cracked and the spire of an 11th-century stupa toppled. No structural collapses occurred but ground effects such as liquefaction and lateral spreading were observed. The MMI in Mae Sai corresponded to VI (Strong). Shaking also caused panic in Chiang Rai and Bangkok.[20] In Hanoi, Vietnam, windows shattered and some people evacuated from their homes.[21] Strong shaking was felt in the provinces of Luang Namtha and Bokeo in Laos without casualties or damage. In Xishuangbanna Prefecture, Yunnan, some homes and schools cracked.[22] Tall buildings were temporarily evacuated in Chiang Rai, Menghai County, Nanning and Hanoi.[23] [24]

On 28 March, The Irrawaddy reported many injured survivors at the Tachilek Hospital had "disappeared". The hospital was overwhelmed by an estimated 700 patients a day before the alleged disappearances. Remaining patients and hospital workers said the survivors were "sent away" by local authorities after journalists reported and distributed media on damage and casualties. Locals also reported up to 200 may have died in Shan State.[25]

Aftermath

Most residents in Tachileik spent the night outdoors after being advised by government officials about aftershocks through loudspeakers. Many people in the town did not return to their homes and businesses were closed. Authorities were hampered by road closures in their effort to locate some injured people in the affected areas. The United Nations Office for the Coordination of Humanitarian Affairs received reports of intermittent disruption of services including power, water and telecommunications. A damaged bridge at Tarlay made access to the town challenging for aid and rescue.[26]

More than US$ 3 million had been donated by various countries and organizations for the relief effort.[27] The government of Myanmar provided Ks 1,162 million worth of supplies to the area.[28] On 25 March, the Ministry of Social Welfare, Relief and Resettlement supplied relief tents, tarpaulins, blankets, clothing and food items via a military plane.[29] Two days later, government officials visited Tachilek and Tarlay, meeting affected residents. Affected families were also handled cash assistance, clothing and food. Patients at the Tachilek Station Hospital were also given cash. Government officials also surveyed repair works at the Kengtung–Tachilek Union Highway, Tachilek–Tahlay Road and Tahlay Bridge. By the afternoon of 27 March, buses and small vehicles could drive along the roads and bridge.[30]

The Chinese government provided US$500 thousand in disaster relief and reconstruction of damaged infrastructure.[31] On 26 March, the Thai government donated ฿3 million to the Burmese government and announced further assistance would be provided.[32] India's prime minister Manmohan Singh said his government would provide US$ 1 million for "relief and rehabilitation" in the affected area.[33] Korea also donated US$ 200 thousand to the Myanmar Red Cross Society.[34] Malteser International provided €10 thousand in emergency relief; at its Yangon warehouse, shelters and non-food items were prepared for 300 families.[35] World Vision distributed water and food to over 1,300 residents.[36]

See also

Notes and References

  1. Classification of road damage due to earthquakes. 10.1007/s11069-011-0025-0. 16 June 2024. 2011. Nat Hazards. Springer Science. Panjamani Anbazhagan. Sushma Srinivas. Deepu Chandran. 60. 2 . 425–460.
  2. Web site: National Earthquake Information Center . M 6.9 - 27 km NNW of Tachilek, Myanmar . United States Geological Survey . 10 June 2023 . 24 March 2011 . 9 April 2023 . https://web.archive.org/web/20230409111021/https://earthquake.usgs.gov/earthquakes/eventpage/usp000hyfx/executive . live .
  3. Book: Zaw . Khin . Swe . Win . Barber . A. J. . Crow . M. J. . Nwe . Yin Yin . 48 . Myanmar: Geology, Resources and Tectonics. Geological Society, London, Memoirs . 2017 . The Geological Society of London . 1–17 . 10.1144/M48.1 . Chapter 1 Introduction to the geology of Myanmar. Geological Society, London, Memoirs .
  4. Web site: Magnitude 6.8 - Myanmar . 12 May 2012 . . 11 November 2012 . dead . https://web.archive.org/web/20110630101620/http://earthquake.usgs.gov/earthquakes/recenteqsww/Quakes/usc0002aes.php . 30 June 2011 .
  5. Web site: McCaughey . Jamie . Tapponnier . Paul . Myanmar earthquake of March 24, 2011 - Magnitude 6.8 . Earth Observatory of Singapore . 12 August 2023 . https://web.archive.org/web/20121024030242/http://www.earthobservatory.sg/media/news-and-features/295-myanmar-earthquake-of-march-24th-magnitude-68.html . 24 October 2012 . 25 March 2011.
  6. Morley. C.K.. 2007. Variations in Late Cenozoic–Recent strike-slip and oblique-extensional geometries, within Indochina: The influence of pre-existing fabrics. Journal of Structural Geology. 29. 1. 36–58. 10.1016/j.jsg.2006.07.003. 2007JSG....29...36M .
  7. Wang . Yu . Lin . Yu-Nung Nina . Simons . Mark . Tun . Soe Thura . Shallow Rupture of the 2011 Tarlay Earthquake (Mw 6.8), Eastern Myanmar . Bulletin of the Seismological Society of America . 2014 . 104 . 6 . 2904–2914 . 10.1785/0120120364 . 2014BuSSA.104.2904W . 10 June 2023 . 7 August 2023 . https://web.archive.org/web/20230807184810/https://authors.library.caltech.edu/53322/1/2904.full.pdf . live .
  8. Tun . Soe Thura . Wang . Yu . Khaing . Saw Ngwe . Thant . Myo . Surface Ruptures of the Mw 6.8 March 2011 Tarlay Earthquake, Eastern Myanmar . Bulletin of the Seismological Society of America . 2014 . 104 . 6 . 2915–2932 . 10.1785/0120130321. 2014BuSSA.104.2915T .
  9. Mase . Lindung Zalbuin . Likitlersuang . Suched . Tobita . Tetsuo . Ground Motion Parameters and Resonance Effect During Strong Earthquake in Northern Thailand . Geotechnical and Geological Engineering . 2021 . 39 . 3 . 2207–2219 . 10.1007/s10706-020-01619-5. 2021GGEng..39.2207M . 226202384 .
  10. Ornthammarath . Teraphan . A note on the strong ground motion recorded during the Mw 6.8 earthquake in Myanmar on 24 March 2011 . Bulletin of Earthquake Engineering . 2013 . 11 . 1 . 241–254 . 10.1007/s10518-012-9385-4. 2013BuEE...11..241O . 109326024 .
  11. News: Reuters. Quake kills 74 in Myanmar, aftershock rattles Thailand. 25 March 2011. The Jerusalem Post. 25 March 2011. 18 January 2012. https://web.archive.org/web/20120118051006/http://www.jpost.com/Headlines/Article.aspx?id=213832. live.
  12. News: Asia. World. At least 75 killed in Burma quake: officials. 25 March 2011. Bangkok Post. 25 March 2011.
  13. News: CATDAT Damaging Earthquakes Database 2011 – Annual Review. Earthquake Report. 9 January 2012. 14 January 2012. https://web.archive.org/web/20120530043215/http://earthquake-report.com/2012/01/09/catdat-damaging-earthquakes-database-2011-annual-review/ . 30 May 2012.
  14. News: Myanmar: Earthquake homeless need urgent shelter . 13 June 2023 . The New Humanitarian . ReliefWeb . 1 April 2011 . 7 August 2023 . https://web.archive.org/web/20230807184825/https://reliefweb.int/report/myanmar/myanmar-earthquake-homeless-need-urgent-shelter . live .
  15. News: Myanmar earthquake: Over 70 people dead . 11 June 2023 . Associated Press . NDTV . 26 March 2011 . 11 June 2023 . https://web.archive.org/web/20230611034535/https://www.ndtv.com/world-news/myanmar-earthquake-over-70-people-dead-451184 . live .
  16. News: Zhang. Xiang. 40 killed in Tarlay in Myanmar quake. https://web.archive.org/web/20110515034544/http://news.xinhuanet.com/english2010/world/2011-03/25/c_13797933.htm. dead. 15 May 2011. 25 March 2011. Xinhua News Agency. 25 March 2011.
  17. News: Baptist church collapses after quake, killing 25 . 13 June 2023 . BWAid . ReliefWeb . 24 March 2011 . 9 November 2015 . https://web.archive.org/web/20151109051944/http://reliefweb.int/report/myanmar/baptist-church-collapses-after-quake-killing-25 . live .
  18. News: Fang. Yang. Death toll of Myanmar's earthquake rises to 74, 111 people injured. https://web.archive.org/web/20110515063751/http://news.xinhuanet.com/english2010/world/2011-03/25/c_13798341.htm. dead. 15 May 2011. 25 March 2011. Xinhua News Agency. 25 March 2011.
  19. News: Dozens killed as quake slams Myanmar, Thailand . 11 June 2023 . NBC News . 24 March 2011 . 11 June 2023 . https://web.archive.org/web/20230611020957/https://www.nbcnews.com/id/wbna42249702 . live .
  20. News: Burma earthquake sends shockwaves across Thai border . 11 June 2023 . Associated Press . The Guardian . 24 March 2011 . 11 June 2023 . https://web.archive.org/web/20230611010226/https://www.theguardian.com/world/2011/mar/24/thai-burma-earthquake-chiang-rai . live .
  21. News: Mydans . Seth . Earthquake Hits Myanmar . The New York Times . 11 June 2023 . 24 March 2011 . 1 May 2013 . https://web.archive.org/web/20130501115851/http://www.nytimes.com/2011/03/25/world/asia/25myanmar.html . live .
  22. News: Sherpa . Sherpem . Quake hits Myanmar and the Golden Triangle area . 11 June 2023 . Reuters . DW News . 25 May 2011 . Lucas . Grahame . 11 June 2023 . https://web.archive.org/web/20230611010956/https://www.dw.com/en/quake-hits-golden-triangle-area/a-6483271 . live .
  23. News: AFP. South Asia. Two dead as strong quake hits Myanmar: Officials . 24 March 2011. The Straits Times. 25 March 2011.
  24. News: Yan. Xinhuanet. Myanmar quake rocks part of south China. https://web.archive.org/web/20110512151025/http://news.xinhuanet.com/english2010/china/2011-03/25/c_13796749.htm. dead. 12 May 2011. 24 March 2011. Xinhua News Agency. 25 March 2011.
  25. News: Naing . Saw Yan . Myanmar: Junta Possibly Concealing Earthquake Casualties . 13 June 2023 . The Irrawaddy . 28 March 2011 . https://web.archive.org/web/20110731153255/http://irrawaddy.org/article.php?art_id=21023 . 31 July 2011.
  26. News: Ponnudurai . Parameswaran . Quake Toll Climbs . 13 June 2023 . Radio Free Asia . Khin . May Zaw . 25 March 2011 . 13 June 2023 . https://web.archive.org/web/20230613080014/https://www.rfa.org/english/news/myanmar/quake-03252011140322.html . live .
  27. News: Hseng . Sai Zom . Victims of Shan Quake Still Waiting for More Aid . 12 August 2023 . The Irrawaddy . 3 May 2011.
  28. News: Government of Myanmar . State has provided quake-hit Tahlay with supplies worth K 1162.7 million Vice-President Dr Sai Mauk Kham inspects reconstruction tasks in quake-hit Tachilek, Tahlay . 12 August 2023 . ReliefWeb . 26 June 2011.
  29. News: Government of Myanmar . Myanmar: Relief aids supplied to earthquake victims . 13 June 2023 . ReliefWeb . 26 March 2011 . 7 August 2023 . https://web.archive.org/web/20230807184822/https://reliefweb.int/report/myanmar/myanmar-relief-aids-supplied-earthquake-victims . live .
  30. News: Government of Myanmar . Myanmar: Maj-Gen Aung Than Htut, Commander, SWRR Minister tour earthquake-hit township and villages, provide cash assistance, relief aids to earthquake victims . 13 June 2023 . ReliefWeb . 27 March 2011 . 7 August 2023 . https://web.archive.org/web/20230807184814/https://reliefweb.int/report/myanmar/myanmar-maj-gen-aung-htut-commander-swrr-minister-tour-earthquake-hit-township-and . live .
  31. Web site: Government of the People's Republic of China . Chinese Government Provided Disaster Relief for Quake-hit Myanmar . 13 June 2023 . 28 March 2011 . 13 June 2023 . https://web.archive.org/web/20230613082317/http://english.mofcom.gov.cn/aarticle/newsrelease/significantnews/201103/20110307469374.html . live .
  32. News: Suvansombut . Nuppol . Thailand donated 3 million THB to help quake stricken Myanmar . 13 June 2023 . National News Bureau of Thailand . 26 March 2023 . https://web.archive.org/web/20110530181049/http://thainews.prd.go.th/en/news.php?id=255403260008 . 30 May 2011.
  33. News: India provides USD 1 million assistance to quake-hit Myanmar . 13 June 2023 . The Times of India . ReliefWeb . 29 March 2011 . 7 August 2023 . https://web.archive.org/web/20230807185308/https://reliefweb.int/report/myanmar/india-provides-usd-1-million-assistance-quake-hit-myanmar . live .
  34. News: Government of Myanmar . Cash donated for quake victims of Tahlay . 12 August 2023 . ReliefWeb . 5 May 2011.
  35. News: Malteser International . Earthquakes in Myanmar: Malteser International staff on its way to earthquake region . 13 June 2023 . ReliefWeb . 25 March 2011 . 7 August 2023 . https://web.archive.org/web/20230807185317/https://reliefweb.int/report/myanmar/earthquakes-myanmar-malteser-international-staff-its-way-earthquake-region . live .
  36. News: World Vision . Myanmar: World Vision Responds in Tar Lay and Mong Lin Townships . 13 June 2023 . ReliefWeb . 26 March 2011 . 7 August 2023 . https://web.archive.org/web/20230807195240/https://reliefweb.int/report/myanmar/myanmar-world-vision-responds-tar-lay-and-mong-lin-townships . live .

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