The 1995 Menglian earthquake or 1995 Myanmar–China earthquake occurred on 12 July at 05:46:43 local time in the Myanmar–China border region. The earthquake had an

epicenter The epicenter, epicentre () or epicentrum in seismology is the point on the Earth's surface directly above a hypocenter or focus, the point where an earthquake or an underground explosion originates. Surface damage Before the instrumental pe ...

on the

Myanmar Myanmar, ; UK pronunciations: US pronunciations incl. . Note: Wikipedia's IPA conventions require indicating /r/ even in British English although only some British English speakers pronounce r at the end of syllables. As John Wells explai ...

side of the border, located in the mountainous region of

Shan State Shan State ( my, ရှမ်းပြည်နယ်, ; shn, မိူင်းတႆး, italics=no) also known by the endonyms Shanland, Muang Tai, and Tailong, is a state of Myanmar. Shan State borders China (Yunnan) to the north, Laos ( ...

. It registered 7.3 on the Chinese surface wave magnitude scale () and 6.8 on the

moment magnitude scale The moment magnitude scale (MMS; denoted explicitly with or Mw, and generally implied with use of a single M for magnitude) is a measure of an earthquake's magnitude ("size" or strength) based on its seismic moment. It was defined in a 1979 pape ...

(). With a maximum Mercalli intensity assigned at VIII, the quake killed eleven people and left another 136 injured. Over 100,000 homes in both countries were destroyed and 42,000 seriously damaged. Some damage to structures were also reported in Chiang Mai and

Chiang Rai Chiang Rai ( th, เชียงราย, ; nod, , เจียงฮาย, ) is the northernmost major city in Thailand, with a population of about 200,000 people. It is located in Mueang Chiang Rai District, Chiang Rai Province. Chiang Rai ...

Thailand Thailand ( ), historically known as Siam () and officially the Kingdom of Thailand, is a country in Southeast Asia, located at the centre of the Indochinese Peninsula, spanning , with a population of almost 70 million. The country is b ...

. The low death toll from this earthquake was attributed to an early warning issued prior to it happening. Precursor events including foreshocks and some seismic anomalies led to an evacuation of the area before the mainshock struck. It is thought to be one of the few successfully predicted earthquakes in history.

Tectonic setting

The Shan Plateau which encompass Yunnan and Shan State is crisscrossed by strike-slip structures to accommodate crustal rotation of the Sunda Block and deformation as a result of the India-Asia collision where the

Indian Plate The Indian Plate (or India Plate) is a minor tectonic plate straddling the equator in the Eastern Hemisphere. Originally a part of the ancient continent of Gondwana, the Indian Plate broke away from the other fragments of Gondwana , began ...

is underthrusted beneath the

Eurasian Plate The Eurasian Plate is a tectonic plate that includes most of the continent of Eurasia (a landmass consisting of the traditional continents of Europe and Asia), with the notable exceptions of the Indian subcontinent, the Arabian subcontinent and ...

. The Shan Plateau formed by uplift along the Shan Scarp Fault Zone, an inactive shear zone and reverse or

thrust fault A thrust fault is a break in the Earth's crust, across which older rocks are pushed above younger rocks. Thrust geometry and nomenclature Reverse faults A thrust fault is a type of reverse fault that has a dip of 45 degrees or less. If ...

along its western base. Located east of the Shan Scarp Fault is the active

Sagaing Fault The Sagaing Fault is a major fault in Burma, a mainly continental right-lateral transform fault between the Indian Plate and Sunda Plate. It links the divergent boundary in the Andaman Sea with the zone of active continental collision along ...

, a dextral

transform fault A transform fault or transform boundary, is a fault along a plate boundary where the motion is predominantly horizontal. It ends abruptly where it connects to another plate boundary, either another transform, a spreading ridge, or a subduct ...

that separates the

Burma Plate The Burma Plate is a minor tectonic plate or microplate located in Southeast Asia, sometimes considered a part of the larger Eurasian Plate. The Andaman Islands, Nicobar Islands, and northwestern Sumatra are located on the plate. This island arc ...

from the Sunda Plate. At the northern boundary of the Shan Plateau lies the

Red River Fault The Red River Fault or Song Hong Fault ( vi, Đới Đứt Gãy Sông Hồng) is a major fault in Yunnan, China and Vietnam which accommodates continental China's (Yangtze Plate) southward movement It is coupled with that of the Sagaing Fault in ...

, an active 1,000 km-long dextral fault. Bookshelf-style faulting as a result of shear deformation between the Red River and Sagaing faults have resulted in predominantly right-lateral strike-slip faulting within the Shan Plateau.

Earthquake

The earthquake occurred as a result of dextral strike-slip faulting at a shallow depth in the Shan Plateau. It ruptured a previously unmapped northwest–southeast striking strike-slip structure not far from the faults involved in the

1988 Lancang–Gengma earthquakes The 1988 Lancang–Gengma earthquakes (simplified Chinese: 澜沧江－耿马地震; traditional Chinese: 瀾滄江－耿馬地震; pinyin: ''Láncāngjiāng-gěng mǎ dìzhèn''), also known as the 11.6 earthquakes by the Chinese media were a pai ...

. Strike-slip faulting within the Shan Plateau are the result of "bookshelf-style" faulting, caused by crustal deformation as it is situated between the

and

. It is believed that the 1995 earthquake was triggered by the transfer of stress from the 1988 earthquake. Modelling of the earthquake suggest most of the displacements in the southeastern

rupture Rupture may refer to: General * Rupture (engineering), a failure of tough ductile materials loaded in tension Anatomy and medicine * Abdominal hernia, formerly referred to as "a rupture" * Achilles tendon rupture * Rupture of membranes, a "wate ...

zone occurred at depths of 0 to 6 km. The greatest slip was detected at 4 km beneath the surface, having moved by 1.9 meters. In the northwestern rupture, the fault had a maximum slip of 2.5 meters, traced to 5 km depth. Rupture was also detected on the surface. The total length of the northwestern and southeastern rupture is approximately 38 km.

Foreshocks and aftershocks

In the days leading up to the

mainshock In seismology, the mainshock is the largest earthquake in a sequence, sometimes preceded by one or more foreshocks, and almost always followed by many aftershocks. Foreshock A foreshock is an earthquake that occurs before a larger seismic eve ...

in this earthquake sequence, there was a series of

foreshock A foreshock is an earthquake that occurs before a larger seismic event (the mainshock) and is related to it in both time and space. The designation of an earthquake as ''foreshock'', ''mainshock'' or aftershock is only possible after the full se ...

s. The largest of which measured 5.5 and 6.2 on the

Richter scale The Richter scale —also called the Richter magnitude scale, Richter's magnitude scale, and the Gutenberg–Richter scale—is a measure of the strength of earthquakes, developed by Charles Francis Richter and presented in his landmark 1935 ...

(). According to the Yunnan Seismic Network Center, in the 100 days after the 7.3 mainshock, some 872 aftershocks were recorded with a magnitude greater than 2.0 . Most of the aftershocks were recorded within the first 100 days after the earthquake. The aftershocks only released 4% of the total energy released during the mainshock. The

United States Geological Survey The United States Geological Survey (USGS), formerly simply known as the Geological Survey, is a scientific agency of the United States government. The scientists of the USGS study the landscape of the United States, its natural resources, ...

recorded the largest foreshocks at 5.9 and 5.0 . Three additional foreshocks had magnitudes of 4.9 or 4.7. The 5.9 foreshock resulted in some damage in Menglian County and was felt in Thailand.

Prediction

Between 19 September 1994 and 12 May 1995, a cluster of earthquakes measuring 4.7 or greater was detected on the Myanmar-China border region. Seismologists also detected strange anomalies in the seismological parameters in that region. Changes to water levels in

Shidian County Shidian County () is under the administration of the prefecture-level city of Baoshan, in the west of Yunnan Yunnan , () is a landlocked province in the southwest of the People's Republic of China. The province spans approximately and h ...

were also interpreted as signs of a large earthquake. After the 6.2 foreshock on July 10, the Yunnan Seismological Bureau dispatched a team to the region closest to the epicenter. A meeting was also conducted and seismologists concluded that a mainshock of magnitude of ~7.0 should strike. An evacuation order was recommended by scientists from the Yunnan Provincial Earthquake Administration after the forecast. Less than 30 hours after that forecast, the mainshock struck.

Intensity

The highest shaking intensity was located in Myanmar. In Yunnan Province, the earthquake was strongly felt over an area 10,400 km². The districts and prefectures in Yunnan that were affected included the

Simao District Simao District (; formerly known as Cuiyun District) is a district under the jurisdiction of Pu'er City, Yunnan Province, China. It is the seat of Pu'er Prefecture. Formerly both Simao and the surrounding region of Pu'er prefecture played a major ...

Linxiang District Linxiang District () is a district of the city of Lincang, Yunnan province, China. Administrative divisions Linxiang District has 2 subdistricts, 1 town, 5 townships and 2 ethnic townships. ;2 subdistricts * Fengxiang () * Mangpan () ;1 town * ...

and

Xishuangbanna Dai Autonomous Prefecture Xishuangbanna, Sibsongbanna or Sipsong Panna ( Tham: , New Tai Lü script: ; ; th, สิบสองปันนา; lo, ສິບສອງພັນນາ; shn, သိပ်းသွင်ပၼ်းၼႃး; my, စစ်ဆောင်� ...

. Thirty-nine townships and 2,242 villages across five counties;

Menglian Menglian Dai, Lahu and Va Autonomous County () is an autonomous county in the southwest of Yunnan, Yunnan Province, China, bordering Ximeng County to the north, Lancang County to the north, northeast, and east, and Burma's Shan State to the south ...

, Ximeng, Lancang, Cangyuan and

Menghai Menghai County (; Tai Lu: ᨾᩮᩨ᩠ᨦᩁᩣ᩠ᨿ ''Meng Haai'' lo, ເມືອງຮາຍ) is a county under the jurisdiction of Xishuangbanna Dai Autonomous Prefecture, in the far south of Yunnan, China, bordering Burma's Shan State to th ...

were located within the earthquake zone, impacting an estimated 127,420 households housing 577,188 people. Intensity VIII on the

China Seismic Intensity Scale The China seismic intensity scale (CSIS) is a national standard in the People's Republic of China used to measure seismic intensity. Similar to EMS-92 on which CSIS drew reference, seismic impacts are classified into 12 degrees of intensity, or ' ...

covered an area of 110 km² in Yunnan. Many brick and wood constructed walls of residential buildings suffered large cracks. Structural deformation to roof trusses and some building collapses occurred within this intensity zone. North-east and northwest-trending

fissure A fissure is a long, narrow crack opening along the surface of Earth. The term is derived from the Latin word , which means 'cleft' or 'crack'. Fissures emerge in Earth's crust, on ice sheets and glaciers, and on volcanoes. Ground fissure ...

s up to 2 meters wide were reported. These fissures ran for approximately 2 km. Some minor landslides were also observed. The zone of intensity VII extended north at Wenggake of

Ximeng County Ximeng Va Autonomous County (; Va: or ) is an autonomous county under the jurisdiction of Pu'er City, in the southwest of Yunnan Province, China, bordering Myanmar's Shan State to the west. Wa/Va people, who speak the Wa language, are the m ...

Menglian County Menglian Dai, Lahu and Va Autonomous County () is an autonomous county in the southwest of Yunnan Province, China, bordering Ximeng County to the north, Lancang County to the north, northeast, and east, and Burma's Shan State to the south and we ...

in the east and Lalei in the south for an area of 1580 km². Many brick and wood constructed homes in this zone were severely cracked. Many walls were either badly damaged or had totally collapsed. Some roof shingles on homes also suffered major damage during the tremor. Intensity VI zone covered a 10400 km² area, from extends to Nuoliang in Cangyuan County in the north, Fubang in Lancang County in the east, and Daluo in Menghai County in the south. Most masonry and wooden buildings had minor damage such as small cracks in the walls. Minimal damage on roof shingles on most structures in the zone. Overall, most structures had limited damage because they were well retrofitted and constructed with seismic codes in place after the 1988 earthquakes.

Impact

A preliminary report by

ReliefWeb ReliefWeb is a humanitarian information portal founded in 1996. The portal now hosts more than 720,000 humanitarian situation reports, press releases, evaluations, guidelines, assessments, maps and infographics. The portal is an independent veh ...

on July 12 stated that two women suffered fatal heart attacks while 36 individuals were injured, two of them seriously. Nineteen buildings were destroyed while many schools, factories and public infrastructures were damaged. A team of scientists were assigned to survey the area but could not reach the affected area due to road damage. In Chiang Rai, Thailand, the earthquake damaged a major electrical generator, cutting power to many the town. The Government of Thailand also ordered that dams reserviors and bridges be inspected for damage. According to an estimate by

Xinhua news agency Xinhua News Agency (English pronunciation: )J. C. Wells: Longman Pronunciation Dictionary, 3rd ed., for both British and American English, or New China News Agency, is the official state news agency of the People's Republic of China. Xinhua ...

on July 19, the total damage caused by earthquake was US$36 million. At least 329 schools, 143 hospitals, 200,000 homes, 165 government offices and more than 500 factories and military bases in Menglian, Ximeng, Lancang and Cangyuan counties were significantlly damaged by the quake. The death toll was also revised to 11 while the number of injured rose to 136. A further 600,000 people were impacted by the quake as well.

Response

After the mainshock struck, the Yunnan Seismological Bureau immediately entered a state of emergency, establishing headquarters and sending more scientists to Menglian to plan disaster assessments, inspections, surveillance, and send reports. The National Earthquake Administration and the People's Government of Yunnan Province formally praised the Yunnan Seismological Bureau for the prediction of the earthquake, resulting in a minimal loss of life.

References

External links

* {{DEFAULTSORT:1995 Myanmar-China earthquake 1995 earthquakes Earthquakes in Myanmar Earthquakes in Yunnan 1995 in China 1995 in Myanmar July 1995 events in Asia 1995 in science