2021 Maduo earthquake explained

2021 Maduo earthquake
Timestamp:2021-05-21 18:04:13
Isc-Event:620437814
Anss-Url:us7000e54r
Local-Date:22 May 2021
Local-Time:02:04 (China Standard Time)
Magnitude:7.4
7.4
Depth:17km (11miles)
Location:34.586°N 98.255°W
Affected:Qinghai & Tibet, China
Damages:¥4.1 billion ($646 million USD)[1]
Intensity:[2]

[3]
Aftershocks:Multiple. Largest is an 5.5[4]
Casualties:
  • 19 injured (official)[5]
  • 20 dead, 300 injured, 13 missing (anonymous source)

The 2021 Maduo earthquake, also known as the 5.22 earthquake struck Madoi County in Qinghai Province, China on 22 May at 02:04 local time.[6] The earthquake had a moment magnitude and surface-wave magnitude of 7.4.[7] [8] [9] [10] Highway bridges, roads and walls collapsed as a result of the earthquake.[11] According to an anonymous source, at least 20 people were killed, 300 were injured, and 13 were missing.[12] Officials stated that there were no deaths but 19 people sustained minor injuries.[13] It was the strongest in China since 2008.[14] It was assigned a maximum intensity of X in Machali, Maduo County on the China seismic intensity scale and Modified Mercalli intensity scale.[15] This earthquake was preceded by another unrelated earthquake that occurred 5 hours earlier in Yunnan.[16] [17]

Tectonic setting

Western Sichuan is situated at the edge of the Tibetan Plateau in a vast zone of complex continental deformation caused by the collision of the Indian Plate with the Eurasian Plate. As the thrusting of the Indian Plate beneath the Eurasian Plate along the Himalayas continues, the continental crust within the Eurasian Plate is actively uplifted and thickened, forming the Tibetan Plateau. As there are no active thrust structures within the plateau, compression is accommodated by strike-slip motion along large structures including the Altyn Tagh Fault, Kunlun Fault, Haiyuan Fault and Xianshuihe fault system. Left-lateral strike-slip motion squeezes the crustal blocks of the Tibetan Plateau outwards, forcing it to move eastwards. Meanwhile, the strike-slip motion also results in east-west extension of the plateau, causing normal faults to break within the thickened crust.[18] [19]

One of these blocks is the Bayan Har block; bounded to the east by the Longmenshan Fault, Kunlun Fault to the north, and Xianshuihe fault system in the south.

Earthquake

According to the United States Geological Survey (USGS), the earthquake occurred as a result of dominantly left-lateral strike-slip faulting with a component of normal dip-slip. It had an estimated focal depth of 10–17 km. In a matter of days after the event, expert seismologists in China confirmed that the event occurred on the Kunlunshankou–Jiangcuo Fault; a left-lateral fault located within the Bayan Har block. This fault is located approximately 70–80 km south of the much larger Kunlun Fault.[20]

Analysis of the USGS preliminary finite fault model of the slip distribution suggest the rupture was about 180 km long and the greatest slip was at 3.3 meters.[21] A research paper soon to be published in Science Bulletin found that the largest surface displacements measured 2.4 meters, while the use of satellite imagery to model the earthquake rupture found a maximum slip of 6 meters near the hypocenter.[22] In another earthquake model, up to 7 meters of coseismic slip occurred on the shallow 12 km of the rupture. Meanwhile, another study published in Geophysical Research Letters inferred a maximum slip of 9.3 meters at a depth of 7 km.[23] Field analysis show the quake occurred on the Jiangcuo Fault.[24] Parallel to the Jiangcuo Fault are the Maduo-Grande, South Gande, Dari, and Xizangdagou-Changmahe faults, which did not rupture. Based on inferring the locations of the aftershock zone, which extended for approximately 170 km, and the location of the mainshock epicenter, the event involved a bilateral rupture on the strike-slip fault.[25] At the eastern and western termination of the earthquake rupture, a secondary segment also ruptured. The secondary rupture in the west measured longer than that of the east. Further analysis of the event by seismologists indicate it was a supershear earthquake.[26]

Scientific reactions

Experts from the China Earthquake Networks Center (CENC) said that it is unlikely that another similar-sized earthquake would strike the same area again in the near future.[27] They added that this earthquake likely occurred within the Bayan Har block, a piece of continental crust in the Tibetan Plateau. Its main boundaries are the Xianshuihe Fault to the south and the Kunlun Fault to the north.[28] The largest earthquakes in the vicinity of the May 22 event are the 2001 Kunlun earthquake and the 1937 Tuosuo Lake earthquake,[29] [30] both measuring 7.8 on the moment magnitude scale and involving a rupture on the Kunlun Fault.[31] [32] The earthquake was unexpected and a surprise to seismologists who had previously thought the Bayan Har block was not capable of producing large earthquakes, and that its interior was tectonically stable.

Aftershocks

The magnitude 7.4 earthquake was followed by many aftershocks, the largest measuring up to 5.5 on the body wave magnitude scale. Two additional aftershocks measured 5.4 . The aftershocks were distributed along the entire length of the rupture.

Only aftershocks of magnitude 5.0 or greater are included in this table.

Time (UTC)LatitudeLongitudeMagnitude MMISource
2021-05-21 18:04:1334.586°N98.255°E7.4X
2021-05-21 18:10:4134.576°N98.295°E5.2-[33]
2021-05-21 18:12:1534.624°N98.473°E5.5VII
2021-05-21 18:13:0134.482°N99.084°E5.4VI[34]
2021-05-22 02:29:3734.936°N97.448°E5.1-[35]
2021-05-22 02:38:4534.540°N98.927°E5.1-[36]
2021-05-22 03:21:1834.730°N98.086°E5.2-[37]
2021-05-30 04:50:0934.614°N98.220°E5.1-[38]
2021-05-30 06:55:1534.587°N34.587°N5.2-[39]
2021-06-03 05:55:1834.723°N97.841°E5.0VI[40]
2021-07-08 13:23:2534.676°N97.917°E5.1-[41]
2021-08-13 04:21:3734.598°N97.428°E5.4VII[42]

Intensity

2021 Maduo earthquake seismic intensities
Locations Felt area (km3)
Machali69
Machali, Huanghe Township, Dawu Town, Youyun Township, Maqên County1,079
Tehetu Township, Huashixia, Gyaring Lake, Youyun Township2,295
Youyun Township, Dawu Township, Maqin County, Tehetu Township, Darlag County10,650
Dangluo Township, Tehetu Township, Jiangqian Township, Qingzhen Township, Xiagongma Township, Ganglong Township, Gadê County, Qumarlêb County, Yüxü, Qingshuihe Town, Dulan County, Qaidam, Sêrxü County39,611

The Ministry of Emergency Management and the China Earthquake Administration conducted a field analysis of 55 affected areas to investigate the effects of the earthquake. The survey results were compiled to create an intensity map of the earthquake which was released on 28 May.[43] According to the findings, 3 cities, prefectures, 7 counties, 32 townships in Qinghai Province, and 1 city, prefecture, 1 county, 4 townships in Sichuan Province were located within the seismic intensities VI–X on the China seismic intensity scale.[44]

The meizoseismal area of the earthquake was in Machali, a town in Maduo County, Golog Tibetan Autonomous Prefecture. The earthquake has its maximum intensity of shaking felt in this region. It was assigned X on the China seismic intensity scale for an area of 69 km2. Such level of intensity would result in bridge piers collapsing and surface fissuring. Intensity IX was felt in two separate areas for 1,069 km2 and 375 km2 respectively along the fault trace. Intensity VIII was felt for a larger 2,295 km2. The earthquake was felt as far as Lanzhou, Xi'an and Chengdu.[45]

Impact

Official words from Chinese authorities stated that 30,000 residents were affected, no deaths occurred and 19 people from Maduo and Maqin counties were injured.[46] Most residents sustained minor injuries, 17 of whom were discharged from the hospitals after receiving treatment.[47] [48] The relatively few number of casualties was attributed to the low population density of the area around the earthquake. On June 1, according to an unidentified Tibetan source, there were 20 deaths, over 300 injured, and 13 missing. The source cited by Radio Free Asia stated that residents in Maduo County and Tibet were prohibited to spread any information of casualties. An estimated 32,000 or more people were displaced.[49]

The earthquake caused damage to at least 625 homes and seven barns in the Huanghe Township area. In Zhalinghu Township, two homes and a barn collapsed due to the shock. Another barn was destroyed in Machali Town. In Huashixia Town, the earthquake collapsed 16 homes. Two parallel bridges of the G0613 Xining–Lijiang Expressway in Maduo County collapsed under the effects of the shock.[50] [51] The bridges were identified as the Yematan No. 2 Bridge of Yugong Expressway and Changma Bridge of Huajiu Expressway.[52] Sections of other major highways were also seriously damaged and deformed beyond use.[53] According to the Qinghai Provincial Transportation Department, the all roads and highways affected by the earthquake were temporarily closed and immediately attended to by repair workers.[54]

Displaced residents relocated to three temporary residential settlements. Cotton tents were used as makeshift homes to those affected. Medical workers were also brought to the scene to assist. Some 186 boarding schoolchildren in Huanghe Township had to be moved to temporary shelters because of the tremors.[55] Immediate repair works to communication services and power lines were also carried on. Checks were also conducted at nearby reservoirs and hydroelectric power stations for damage.[56]

Many land fissures, landslides, and ground failures were reported around a zone greater than 100 km in length. Total destruction was observed to homes at Xuema, a small village located at the eastern terminus of the rupture where a small zone of the intensity was assigned IX. A 1.5-km-long surface fissure caused by liquefaction was reported near the village. Approximately 100 meters the north, a 1.5-km-long surface rupture was reported. Major damage was reported in brick structures. The collapse of a house buried two people while another two had minor injuries.[57]

See also

Further reading

External links

Notes and References

  1. A summary of seismic activities in and around China in 2021. China Earthquake Networks Center. Yanyan Han. Yang Zang. Lingyuan Meng. Yue Wang. Shiguang Deng. Yawei Ma. Mengyu Xie. 2022 . 2 . 3 . 100157 . 10.1016/j.eqrea.2022.100157 . 2022EaRA....200157H . 250027593 . free.
  2. News: Zhang Ni . 四、五月份是强震高发期？地震专家解析网友疑惑 . 23 May 2021 . Xinhua Newspaper Network . 22 May 2021 . Chinese.
  3. Wenkai Chen . Dun Wang . Can Zhang . Qiang Yao . Hongjun Si . Estimating seismic intensity maps of the 2021 Mw 7.3 Madoi, Qinghai and Mw 6.1 Yangbi, Yunnan, China earthquakes . Journal of Earth Science . 2021 . 33 . 4 . 839–846 . 10.1007/s12583-021-1586-9 . 247246109 .
  4. Web site: M 5.5 - Southern Qinghai, China . earthquake.usgs.gov . USGS . 30 May 2021.
  5. News: Li Ning . 19 people were injured and 17 people were discharged from hospital after the May 22 earthquake in Maduo, Qinghai . 31 May 2021 . Xinhua News Agency . Xinhuanet . 27 May 2021 . Chinese.
  6. News: Yue Hongbin, Yan Jiaqi . 青海省玛多县发生7.4级地震 西宁震感强烈 . 22 May 2021 . People's Daily . 22 May 2021.
  7. Web site: Global CMT Catalog Search 202105211804A . globalcmt.org . . 22 November 2021 . 21 May 2021.
  8. Web site: M 7.3 - Southern Qinghai, China. 2021-05-21. earthquake.usgs.gov.
  9. Web site: A magnitude 7.4 earthquake occurred in Maduo County, Guoluo Prefecture, Qinghai Province at 2:4 on May 22 . China Earthquake Administration . 22 May 2021 . Chinese.
  10. Web site: M 7.4 - SOUTHERN QINGHAI, CHINA - 2021-05-21 18:04:14 UTC . . 2 November 2021 . 21 May 2021.
  11. News: 青海玛多7.4级地震 县城区域有围墙倒塌 救援队伍已集结 . 22 May 2021 . Sina Corp . 22 May 2021.
  12. Web site: At Least 20 Dead, More Than 300 Injured in Qinghai Quake as China Imposes Information Lockdown. Radio Free Asia.
  13. News: 13 people were slightly injured in Qinghai Maduo earthquake . 22 May 2021 . Xinhua News Agency . 22 May 2021.
  14. Web site: Powerful earthquakes hit Chinese cities, 3 dead. 2021-05-25. newsonair.com. 25 May 2021. https://web.archive.org/web/20210525195525/http://newsonair.com/Main-News-Details.aspx?title=Powerful-earthquakes-hit-Chinese-cities,-3-dead&id=417624. dead.
  15. News: Tang Guorong . The Ministry of Emergency Management released the intensity map of the Qinghai Maduo M7.4 earthquake . 29 May 2021 . Beijing News . Chinese.
  16. Web site: M 6.1 - 28 km NW of Dali, China. 2021-05-21. earthquake.usgs.gov.
  17. Web site: Welle (www.dw.com). Deutsche. China: Earthquakes shake northwestern, southwestern regions DW 21.05.2021. 2021-05-25. Deutsche Welle. en-GB.
  18. J. R. Elliott, R. J. Walters, P. C. England, J. A. Jackson, Z. Li, B. Parsons . Extension on the Tibetan plateau: recent normal faulting measured by InSAR and body wave seismology . Geophysical Journal International . 2010 . 183 . 2 . 503–535 . 10.1111/j.1365-246X.2010.04754.x . 2010GeoJI.183..503E . 134590278 . free .
  19. Weijun Gan . Peizhen Zhang . Zheng-Kang Shen . Zhijun Niu . Min Wang . Yongge Wan . Demin Zhou . Jia Cheng . Present-day crustal motion within the Tibetan Plateau inferred from GPS measurements . Journal of Geophysical Research: Solid Earth . 2007 . 112 . B8 . 10.1029/2005JB004120 . American Geophysical Union. 2007JGRB..112.8416G . free .
  20. Zhiyu Gao . Yanchuan Li . Xinjian Shan . Chuanhua Zhu . Earthquake Magnitude Estimation from High-rate GNSS Data: A Case Study of the 2021 Mw 7.3 Maduo Earthquake . Remote Sensing . 8 November 2021 . 13 . 4478 . 4478 . 10.3390/rs13214478. 2021RemS...13.4478G . free .
  21. Yujiang Li . Luyuan Huang . Rui Ding . Shuxin Yang . Lei Liu . Shimin Zhang . Haoqing Liu . Coulomb stress changes associated with the M7.3 Maduo earthquake and implications for seismic hazards . Natural Hazards Research . 2021 . 1 . 2 . 95–101 . 10.1016/j.nhres.2021.06.003 . 2021NatHR...1...95L . 2666-5921. free .
  22. Jihong Liu . Jun Hu . Zhiwei Li . Zhangfeng Ma . Lixin Wu . Weiping Jiang . Guangcai Feng . Jianjun Zhu . Complete three-dimensional coseismic displacements related to the 2021 Maduo earthquake in Qinghai Province, China from Sentinel-1 and ALOS-2 SAR images . Earth and Space Science Open Archive . 2021 . 19 . 10.1002/essoar.10507403.1 . 237916038 . 4 July 2021.
  23. Rumeng Guo . Hongfeng Yang . Yu Li . Yong Zheng . Lupeng Zhang . Complex Slip Distribution of the 2021 Mw 7.4 Maduo, China, Earthquake: An Event Occurring on the Slowly Slipping Fault . Seismological Research Letters. 2022 . 93 . 2A . 653–665 . 10.1785/0220210226 . 2022SeiRL..93..653G . 244817728 .
  24. Junjie Ren . Zhiwen Zhang . Hailong Gai . Wenjun Kang . Typical Riedel shear structures of the coseismic surface rupture zone produced by the 2021 Mw 7.3 Maduo earthquake, Qinghai, China, and the implications for seismic hazards in the block interior . Natural Hazards Research . 2021 . 1 . 4 . 145–152 . 10.1016/j.nhres.2021.10.001 . 2021NatHR...1..145R . 239552856 . free .
  25. Weilai Wang . Lihua Fang . Jianping Wu . Hongwei Tu . Liyi Chen . Guijuan Lai . Long Zhang . Aftershock sequence relocation of the 2021 MS7.4 Maduo Earthquake, Qinghai, China . Science China Earth Sciences . 2021 . 64 . 8 . 1371–1380 . 10.1007/s11430-021-9803-3. 2021ScChD..64.1371W . 236181805 .
  26. Xu Zhang . Wanpeng Feng . Hailin Du . Sergey Samsonov . Lei Yi . Supershear Rupture During the 2021 MW 7.4 Maduo, China, Earthquake . Geophysical Research Letters . 2022 . 49 . 6 . 10.1029/2022GL097984 . 2022GeoRL..4997984Z . 247485288 . free .
  27. News: 专家：青海玛多县地震原震区近期发生7级以上地震的可能性不大 . 22 May 2021 . Xinhua News Agency . 22 May 2021 . Chinese . Xue Tao.
  28. Yujun Sun, Taoyuan Fan, Chunjing Zhou, Zhonghai Wu . The Evolution of Stress and Strain around the Bayan Har Block in the Tibetan Plateau . Journal of Earthquakes . 2015 . 2015 . 10.1155/2015/971628 . 971628. free .
  29. Web site: M 7.8 - southern Qinghai, China . earthquake.usgs.gov . USGS . 22 May 2021.
  30. Web site: M 7.8 - southern Qinghai, China . earthquake.usgs.gov . USGS . 22 May 2021.
  31. Jianming Guo, Aiming Lin, Guoqiang Sun, Jianjing Zheng . Surface Ruptures Associated with the 1937 M 7.5 Tuosuo Lake and the 1963 M 7.0 Alake Lake Earthquakes and the Paleoseismicity along the Tuosuo Lake Segment of the Kunlun Fault, Northern Tibet . Bulletin of the Seismological Society of America . 2007 . 97 . 2 . 474–496 . 10.1785/0120050103 . 2007BuSSA..97..474G . 22 May 2021.
  32. D. P. Robinson, C. Brough, S. Das . The Mw 7.8, 2001 Kunlunshan earthquake: Extreme rupture speed variability and effect of fault geometry . Journal of Geophysical Research . 2006 . 111 . B8 . B08303 . 10.1029/2005JB004137. 2006JGRB..111.8303R . free .
  33. Web site: M 5.2 - Southern Qinghai, China . earthquake.usgs.gov . USGS . 30 May 2021.
  34. Web site: M 5.4 - Southern Qinghai, China . earthquake.usgs.gov . USGS . 30 May 2021.
  35. Web site: M 5.1 - Southern Qinghai, China . earthquake.usgs.gov . USGS . 22 May 2021.
  36. Web site: M 5.2 - southern Qinghai, China . earthquake.usgs.gov . USGS . 22 May 2021.
  37. Web site: M 5.2 - Southern Qinghai, China . earthquake.usgs.gov . USGS . 22 May 2021.
  38. Web site: M 5.1 - Southern Qinghai, China . earthquake.usgs.gov . USGS . 30 May 2021.
  39. Web site: M 5.2 - Southern Qinghai, China . earthquake.usgs.gov . USGS . 30 May 2021.
  40. Web site: M 5.0 - Southern Qinghai, China . earthquake.usgs.gov . USGS . 3 June 2021.
  41. Web site: M 5.1 - Southern Qinghai, China . earthquake.usgs.gov . USGS . 8 July 2021.
  42. Web site: M 5.4 - Southern Qinghai, China . earthquake.usgs.gov . USGS . 22 August 2021.
  43. News: Xinhua . Qinghai Maduo M7.4 earthquake intensity map released, the highest intensity is 10 degrees . 30 May 2021 . People's Daily . 29 May 2021.
  44. Web site: 玛多"5·22"地震抗震救灾新闻发布会(第八场)召开. 2021-05-29. Qinghai Daily. 2021-12-19. 2021-06-03. https://web.archive.org/web/20210603045655/http://www.qh.gov.cn/zwgk/system/2021/05/29/010384131.shtml. live.
  45. Web site: 青海玛多县发生7.4级地震 兰州西安成都等多地有震感_台网. 2021-05-25. sohu.com. en.
  46. Web site: UNICEF Sends Supplies to Children Affected by an Earthquake in Qinghai Province. 2022-01-19. unicef.cn. en.
  47. News: Xu Peng . 青海玛多"5.22"地震最新通报：17人受轻伤12人出院 2万余人转移安置 . 24 May 2021 . Legal Daily . Rule of Law Daily-Legal Network . 23 May 2021 . Chinese.
  48. News: Hu Guilong . Zhang Tianfu . 青海玛多7.4级地震：17人受轻伤，避险转移安置2万余人 . 23 May 2021 . China News Network . 23 May 2021 . Chinese.
  49. News: China Focus: Quake-hit areas in China resume school . 3 July 2021 . Xinhua News Agency . 24 May 2021 . Xining, China.
  50. News: Liu . Pai . Ms 7.4 earthquake in Maduo County, Qinghai: Five people were slightly injured and the bridge collapsed severely . 23 May 2021 . Baidu . China News Network . 22 May 2021.
  51. Web site: G0613西丽高速野马滩大桥因地震双向坍塌. Sohu. G0613 Xili Expressway Yematan Bridge collapsed by earthquake. live. https://web.archive.org/web/20210525162353/https://www.sohu.com/a/467903027_162522 . 2021-05-25 .
  52. News: Rush to the rescue, Yunnan, Qinghai earthquake, closely aligned with our compatriots . 31 May 2021 . Xinhua News Agency . 22 May 2021.
  53. News: Sun . Zonghe . No casualties have been reported due to the collapse of some roads and bridges due to the Mado 7.4 earthquake in Qinghai . 23 May 2021 . Baidu . 22 May 2021.
  54. News: Tang Ying . Ministry of Transport: All highways damaged by the earthquake in Yunnan and Qinghai have been rushed through . 31 May 2021 . China News . CCTV News Client . 27 May 2021 . Chinese.
  55. Web site: 186 children accommodated at temporary shelter in quake-hit county in Qinghai - Xinhua English.news.cn. 2021-05-23. Xinhua News Agency.
  56. News: Chinanews . 青海玛多7.4级地震：17人受轻伤，避险转移安置2万余人 . 23 May 2021 . ce.cn . 23 May 2021 . Chinese.
  57. Zhang . Yanbo . Xu . Yueren . Li . Wenqiao . Liu . Runchao . Mu . Ruoyu . Li . Jiayi . Zhang . Da . Li . Haofeng . Tian . Qinjian . Coseismic surface rupture characteristics and earthquake damage analysis of the eastern end of the 2021 MS 7.4 Madoi (Qinghai) earthquake . Earthquake Research Advances . 2022 . 2 . 2 . 100133 . 10.1016/j.eqrea.2022.100133 . Elsevier. 2022EaRA....200133Z . 247422588 . free .

This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "2021 Maduo earthquake".

Except where otherwise indicated, Everything.Explained.Today is © Copyright 2009-2024, A B Cryer, All Rights Reserved. Cookie policy.