1988 Lancang–Gengma earthquakes

Coordinates: 22°47′20″N 99°36′40″E / 22.789°N 99.611°E / 22.789; 99.611
Source: Wikipedia, the free encyclopedia.
1988 Lancang–Gengma earthquakes (澜沧江－耿马地震)
epicenter.
epicenter.
1988 Lancang–Gengma earthquakes (China)
epicenter.
epicenter.
1988 Lancang–Gengma earthquakes (Yunnan)
UTC time1988-11-06 13:03:19
 1988-11-06 13:15:43
ISC event419867
 419869
USGS-ANSSComCat
 ComCat
Local date6 November 1988
Local time21:03
 21:15
MagnitudeMw 7.0
 Mw 6.9
Depth18 km (11 mi)
 15 km (9.3 mi)
EpicenterChina–Myanmar border region
22°47′20″N 99°36′40″E / 22.789°N 99.611°E / 22.789; 99.611
TypeStrike-slip
Areas affectedChina, Burma and Thailand
Total damageUS$ 270 million in 1988
Max. intensityCSIS IX (1st shock)

CSIS X (2nd shock)
LandslidesYes
ForeshocksYes
Aftershocks600+
Casualties748–939 fatalities, 7,700+ injured

The 1988 Lancang–Gengma earthquakes (

border with Shan State, Burma.[1] The earthquake measured moment magnitude (Mw ) 7.0 and was followed 13 minutes later by a 6.9 Mw  shock.[2] These earthquakes were assigned a maximum China seismic intensity
of IX and X, respectively. Between 748 and 939 people were killed; more than 7,700 were injured. Both earthquakes resulted in US$270 million (in 1988 dollars) in damage and economic losses. Moderately large aftershocks continued to rock the region, causing additional casualties and damage.

Tectonic setting

A simplified diagram of bookshelf-style faulting

The

deformation as a result of the India–Asia collision, where the Indian Plate is underthrusted beneath the Eurasian Plate. The Shan Plateau formed by uplift along the Shan Scarp Fault Zone, an inactive shear zone and thrust fault along its western base.[3][4] Located east of the Shan Scarp Fault is the active Sagaing Fault, a dextral transform fault that separates the Burma Plate from the Sunda Plate. At the northern boundary of the Shan Plateau lies the Red River Fault, an active 1,000 kilometres (620 mi) long dextral fault.[5]

Earthquakes in this part of

Salween rivers. Dextral structures follow a north-west or north-southernly strike. The earthquakes of 1988 were the result of slip along a dextral fault zone.[7]

In 1995, another earthquake measuring 6.8 Mw  struck the same area.[9] It left at least 11 people dead, destroyed over 100,000 homes, and damaged an additional 42,000.[10] The earthquake may have been triggered by the transfer of stress from the 1988 events.[8]

Earthquake

See also: Earthquake rupture
Major earthquakes in the Yunnan–Shan border region
1912
1923
1923
1950
1950
1976
1952
1952
1941
1941
1995
1922
1922
1988
1988
2011
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Major earthquakes (M6.5+) in the Yunnan–Shan border region[2]

The earthquakes originated along the Longlin–Lancang

Fault Zone; a northwest–southeast striking, 210 kilometres (130 mi)-long structure. Its northern section is a single strand while the southern section comprises a complex anastomosis of faults. Forming in the early to mid-Miocene, this dextral fault has accumulated 17 kilometres (11 mi) of displacement. Its estimated slip rate is 3.4 mm (0.13 in) per year.[11] It was previously a sinistral fault as 30 km (19 mi) of left-lateral offset was observed in a batholith from geological studies.[12]

Right-lateral offsets of 1.4–2 metres (4 ft 7 in – 6 ft 7 in) were measured along the

reverse) component was also measured. These surface ruptures followed a north–northwest strike for about 24 kilometres (15 mi). The first mainshock ruptured an estimated 53 kilometres (33 mi)–70 kilometres (43 mi)-long by 26 kilometres (16 mi)-km-wide fault zone extending northwest–southeast.[11] The maximum measured dextral surface offset was 2.0 metres (6 ft 7 in) and vertical offset was 0.5 metres (1 ft 8 in).[12][14] The fault zone ruptured with a velocity estimated at 2 km (1.2 mi) per second.[11]

Thirteen minutes later, an earthquake with a surface-wave magnitude of 7.2 struck 63 kilometres (39 mi) north–northwest of the first shock.[15] On the moment magnitude scale, it measured 6.9.[2][15] The rupture area was nearly twice that of the 7.7 mainshock. The event sequence is considered a doublet earthquake.[16][11]

Right before the first mainshock, a 2.6 foreshock preceded the disaster, it was the only recorded foreshock in the earthquake sequence.

The two events are largest earthquakes to affect both Yunnan Province and Shan State since 1970 and 1912, respectively. In January 1970, a magnitude 7.7 struck Tonghai County,[17] and in May 1912, Shan State was hit with a magnitude 7.8 earthquake.[18]

Earthquake sequence

Previous seismicity
Date Time (UTC) Magnitude Depth (km) Ref.
1987-11-25 13:09:47 mb 4.6 33.0 [19]
1988-08-14 17:50:52 mb 4.7 [20]
Mainshocks
Date Time (UTC) Magnitude Depth (km) Ref.
1988-11-06 13:03:19 Mw  7.0–7.7
Ms  7.6 		18.0 [13][15][2]
13:15:43 Mw  6.9
Ms  7.2 		10.0 [21][15][2]

Aftershocks

A large aftershock measuring 6.1 Mw  occurred 24 days after the mainshocks.[15] It caused additional injuries and further damage. By December 20, over 600 aftershocks had been recorded.

Aftershocks magnitude 5.0 or greater
Date Time (UTC) Magnitude Depth (km) Notes Ref.
1988-11-06 13:21:04 mb 5.8 10.0 [22]
13:39:48 mb 5.0 [23]
14:13:24 mb 5.1 [24]
16:00:32 mb 5.1 [25]
20:24:24 mb 5.4 [26]
1988-11-07 02:39:56 Mw 5.2 [27]
1988-11-15 10:28:14 Mw 5.3 17.7 [28]
1988-11-18 18:21:44 mb 5.0 10.0 [29]
1988-11-19 01:37:14 mb 5.0 33.0 [30]
1988-11-27 04:17:56 Mw 5.5 15.7 One person injured and some damage.[31] [31]
1988-11-30 08:13:29 Mw 6.1 14.5 Further damage in the affected region. Several people injured. Felt in Kumming.[32][33] [32]
1988-12-19 11:06:57 mb 5.0 33.0 [34]
1988-12-22 03:49:46 mb 5.0 10.0 [35]
1989-05-07 00:38:18 Mw 5.6 33.0 One person died and 91 injured. At least 5,300 homes were damaged in Gengma County. Damaged totaled US$54 million.[36] [37]
1989-06-04 15:07:46 mb 5.0 10.0 [38]

Intensity

Strong ground motion map for the first mainshock

The first mainshock produced shaking which was assigned a maximum of IX on the

Heihe River, west of Fubang Township. Landslides, surface ruptures, liquefaction and ground failure were observed.[16]

Intensity VIII encompassed

Ximeng County to the west. This zone had an axis length of 52 kilometres (32 mi) and a width of 20 kilometres (12 mi), covering an area of 820 km2 (320 sq mi). Nearly every house in the region collapsed, with very few left intact. The earthquake also caused landslides and ground failures throughout.[16]

Cangyuan County in the north to Shangyun, and Lancang County in the south were within the area of VII. The western boundary also extended into Ximeng County, well beyond the Myanmar–China border, into Shan State. Damage was less extreme although some houses collapsed. Light homes remained intact, and much of the damage to ordinary homes reported include cracking of walls. Landslides, ground cracks and sand boils occurred. This zone covered a large area of 3,680 km2 (1,420 sq mi).[16]

Strong to weak shaking was felt in

Mercalli intensity in Chiang Mai was VI (Strong), damaging some buildings.[41]

The second mainshock had a maximum intensity of X.

Cangyuan County in the west. Many houses totally collapsed or were severely compromised in this zone. Many buildings were also seriously damaged. Lightly constructed homes collapsed or tilted due to damage resulting from the rupture. Liquefaction and fissures ejecting water were observed. This zone is a north-west ellipse with a major axis of 25 kilometres (16 mi) and a minor axis of 8 kilometres (5.0 mi), covering an area of 160 km2 (62 sq mi).[16]

The zone of intensity VIII extended from Gengma in the north to Yanshuai and Nuoliang Township in the south. Few homes remained standing and lightweight houses tilted. Damage to the ground was identical to those observed in the zone of IX. This zone followed a north-west ellipse area of 940 km2 (360 sq mi).[16]

Aiguo New Village, Gengxuan Town, Gengma County in the north, to south of the Shuangjiang River in the east, to south of Lancang Shangyun in the south, and west to Minliang of

Adobe houses totally collapsed as a result. Intensity VII was felt for an area of 3,020 km2 (1,170 sq mi). Intensity VI from the second shock covered an area of 32,700 km2 (12,600 sq mi).[16]

Aftermath

Ximeng County was within the seismic intensity VIII zone

Early figures of fatalities were 18 and 37, which could not be revised due to the communication disruptions. Over the next few days, international media reported at least 600 inhabitants killed, mainly in the village of Shanmato which was obliterated. Telecommunication services were cut and severely disrupted. This meant provincial government officials could not provide updated figures on the dead.[42]

On November 9, the death toll totaled 938.[43] Chinese officials stated 748 people died; at least 7,700 people seriously injured; over 3 million affected and 267,000 homeless.[16] They added that the death toll could have been higher had the earthquakes struck near a city. When the earthquakes struck, many residents were outdoors, which factored in the unexpectedly low death toll. A fatality figure of 938 was given to the United Nations and became widely reported.[17] The reported death toll by the Emergency Events Database was 939.[44] It was regarded as China's "worst earthquake in more than a decade".[45] At the time of the earthquakes, the population of Lancang and Gengma counties were 237,000 and 81,000, respectively.[46] In Lancang County, at least 607 people died including 279 in Zhanmapo.[47]

Seventeen counties were heavily damaged. Many homes, roads and communication lines in Lancang and Mengliang counties were destroyed.[33] An estimated 200,000 buildings including 144,000 houses were razed. Over 1.308 million rooms collapsed and 934,800 were damaged.[48] At least 500,000 buildings including 253,000 homes were badly damaged.[33] More than 4,000 essential facilities in Yunnan were damaged. About 1,000 schools, 98 clinics and 29 reservoirs were destroyed. Landslides in the area also damaged highways. The majority of homes constructed of wood and mud, collapsed due to the extreme ground motions, killing its inhabitants.[42] Over 1,000,000 m3 (35,000,000 cu ft) of rockslides damaged highways and blocked rivers, halting water transportation. Kunming, the capital of Yunnan Province, was undamaged, although the earthquakes were felt strongly. More damage was reported in Chiang Rai, Thailand. The total cost of damage was estimated at US$ 269 million (US$693 million in 2023).

Many buildings generally fared well during the earthquakes because of improved construction practices and

seismic retrofitting works prior. Buildings which had survived were built with the consideration of the local seismic hazard. Some buildings including a cinema which was designed to withstand seismic intensity VIII and a residential block made to resist intensity IX were undamaged. These buildings were strengthened before the earthquakes.[48]

Response

Due to its remote location and the lack of communication and damaged roads, rescue and aid transportation efforts faced difficulties getting to the affected areas.[49] Rescus and medical personnel only reached the affected zone on 9 November.[50] The Yunnan government ordered an airlift of medical and relief supplies to help those affected. The governor of Yunnan Province, He Zhiqiang, along with several medical doctors were brought to the disaster scene.[42] Several thousand troops and many military vehicles also visited the affected areas, according to the Ministry of Civil Affairs.[51] Much information about the earthquakes and its devastation were hidden by the Chinese government as the country was going through major political and cultural revolutions at the time.[52] In the early decades of China's communist regime, the guideline was that natural disasters and accidents would not be disclosed unless foreign nationals were involved.[17] It was only in the few years prior to 1988 were these events publicized. At a press conference following the earthquakes, officials disclosed that a magnitude 7.7 event in 1970 resulted in 10,000 deaths.[17]

See also

References

  1. ^ "谨以此片 纪念澜沧11.6大地震三十周年（一）". Sohu. Sohu. 2018-11-07. Retrieved 28 February 2021.
  2. ^ a b c d e ISC (27 June 2022), ISC-GEM Global Instrumental Earthquake Catalogue (1900–2009), Version 9.1, International Seismological Centre
  3. ^ Soe Min. "Fault segmentation and active tectonic criteria of the Shan Scarp Fault Zone, Shan Plateau Region, Myanmar". Mnces 2019.
  4. doi:10.1016/j.jseaes.2004.03.006.{{cite journal}}: CS1 maint: multiple names: authors list (link
    )
  5. S2CID 224901911
    .
  6. hdl:10220/45249.{{cite journal}}: CS1 maint: multiple names: authors list (link
    )
  7. ^
    doi:10.1002/2013JB010762.{{cite journal}}: CS1 maint: multiple names: authors list (link
    )
  8. ^
    ISSN 0303-2434.{{cite journal}}: CS1 maint: multiple names: authors list (link
    )
  9. ^ "M 6.8 - Myanmar". USGS-ANSS. Archived from the original on 2020-10-31.
  10. doi:10.7289/V5TD9V7K
  11. ^
    S2CID 129586363
    .
  12. ^ a b Yu Wang. "Earthquake Geology of Myanmar" (PDF). Dissertation – via Caltech.
  13. ^ a b National Earthquake Information Center. "M 7.7 - Myanmar-China border region". United States Geological Survey. Archived from the original on 2019-11-06. Retrieved 2021-02-23.
  14. S2CID 130422667.{{cite journal}}: CS1 maint: multiple names: authors list (link
    )
  15. ^
    doi:10.1029/89EO00376
    .
  16. ^ a b c d e f g h i Yang, Jideng; Wang, Shiqin. "1988年11月6日云南省澜沧-耿马7.6、7.2级地震". National Seismology Data Center. Yunnan Seismological Bureau. Archived from the original on 11 July 2021. Retrieved 22 February 2021.
  17. ^ a b c d Kristof, Nicholas D. (19 November 1988). "Chinese Disclose That Quake In 1970 Killed About 10,000". The New York Times. Archived from the original on 27 July 2018. Retrieved 23 July 2022.
  18. PMID 31424339
    .
  19. ^ "M 4.6 - Myanmar-China border region". earthquake.usgs.gov. Retrieved 2021-02-23.
  20. ^ "M 4.7 - Myanmar-China border region". earthquake.usgs.gov. Retrieved 2021-02-23.
  21. ^ National Earthquake Information Center. "M 6.4 - Myanmar-China border region". United States Geological Survey. Archived from the original on 2021-11-04. Retrieved 2021-02-23.
  22. ^ National Earthquake Information Center. "M 5.8 - Myanmar-China border region". United States Geological Survey. Retrieved 2021-02-23.
  23. ^ National Earthquake Information Center. "M 5.0 - Myanmar-China border region". United States Geological Survey. Retrieved 2021-02-23.
  24. ^ National Earthquake Information Center. "M 5.1 - Myanmar-China border region". United States Geological Survey. Retrieved 2021-02-23.
  25. ^ National Earthquake Information Center. "M 5.1 - Myanmar-China border region". United States Geological Survey. Retrieved 2021-02-23.
  26. ^ National Earthquake Information Center. "M 5.4 - Myanmar-China border region". United States Geological Survey. Retrieved 2021-02-23.
  27. ^ National Earthquake Information Center. "M 5.2 - Myanmar-China border region". United States Geological Survey. Retrieved 2021-02-23.
  28. ^ National Earthquake Information Center. "M 5.3 - Myanmar-China border region". United States Geological Survey. Retrieved 2021-02-23.
  29. ^ National Earthquake Information Center. "M 5.0 - Myanmar-China border region". United States Geological Survey. Retrieved 2021-02-23.
  30. ^ National Earthquake Information Center. "M 5.0 - Myanmar-China border region". United States Geological Survey. Retrieved 2021-02-23.
  31. ^ a b National Earthquake Information Center. "M 5.5 - Myanmar-China border region". United States Geological Survey. Retrieved 2021-02-23.
  32. ^ a b National Earthquake Information Center. "M 6.1 - Myanmar-China border region". United States Geological Survey. Retrieved 22 February 2021.
  33. ^ a b c UN Department of Humanitarian Affairs (8 November 1988). "China - Earthquake Nov 1988 UNDRO Information Reports 1-7". reliefweb.
  34. ^ National Earthquake Information Center. "M 5.0 - Myanmar-China border region". United States Geological Survey. Retrieved 2021-02-23.
  35. ^ National Earthquake Information Center. "M 5.0 - Myanmar-China border region". United States Geological Survey. Retrieved 2021-02-23.
  36. doi:10.7289/V5TD9V7K
  37. ^ National Earthquake Information Center. "M 5.6 - Myanmar-China border region". United States Geological Survey. Retrieved 2021-02-23.
  38. ^ National Earthquake Information Center. "M 5.0 - Myanmar-China border region". United States Geological Survey. Retrieved 2021-02-23.
  39. doi:10.7289/V5TD9V7K
  40. ^
    S2CID 129529222
    .
  41. ^ Lukkunaprasit, Panitan (1989). State of seismic risk mitigation in Thailand (PDF). Thailand: Chulalongkorn University. Archived from the original (PDF) on 4 March 2022.
  42. ^ a b c Associated Press (8 November 1988). "Chinese quake registers 7.6, death toll hits 600" (PDF). The Observer. Archived (PDF) from the original on 23 November 2021. Retrieved 22 January 2021.
  43. ^ Kristof, Nicholas D. (Nov 9, 1988). "Toll Reported in China Earthquake Reaches 938". The New York Times.
  44. PMID 15958426
    .
  45. ^ "Chinese earthquake worst there in decade". Desert Sun. 9 November 1988. pp. A2. Retrieved 16 May 2023.
  46. ^ "China says toll from quake hits 938, will increase". Desert Sun. New York TImes. 9 November 1988. Retrieved 15 May 2023.
  47. ^ Kristof, Nicholas D. (10 November 1988). "China now says earthquake left 100,000 homeless". New York Times. Retrieved 15 May 2023.
  48. ^ a b Hu, Qingchang; Chung, Yicun (1989). "Yunnan November 6, 1988; M7.6, 7.2 Earthquakes". Earthquake Engineering Research Institute. Archived from the original on 1 August 2013. Retrieved 19 May 2021.
  49. ^ "铭记"11.6"（二）". Sohu. Sohu. 2018-11-08. Retrieved 28 February 2021.
  50. ^ "Teams reach quake area". Vol. 132, no. 19. Press Democrat. 9 November 1988. p. 8. Retrieved 15 May 2023.
  51. ^ Tyson, James L. (9 November 1988). "Peking sends help to Yunnan, 'China's earthquake center'". The Christian Science Monitor. Retrieved 22 January 2021.
  52. ^ Associated Press (10 July 2010). "Hundreds injured in China earthquake". The Guardian. Retrieved 22 January 2021.

External links

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