1927 Gulang earthquake
Encyclopedia
The 1927 Gulang earthquake occurred at 6:32 a.m. on 22 May (22:32 UTC on 21 May). This 7.6 magnitude
event had an epicenter
near Gulang, Gansu
in China
. There were more than 40,900 casualties. It was felt up to 700 km away.
between the Indian Plate and the Eurasian Plate
has formed the Himalayas
and the large uplifted area of the Tibetan Plateau
. The northeastern part of Tibet is affected by the eastward lateral spreading of the Tibetan Plateau. This spreading is accommodated by a series of sinistral (left-lateral) strike-slip faults, including the Atyn Tagh, Haiuyan, Kunlun
and Xianshuihe faults, combined with thrusting
on the Longmenshan fault
. The earthquake ruptured the complex thrust fault system in the Qilian Mountains transpressional zone, formed at a restraining bend on the Haiyuan fault. Another segment of the Haiyuan fault was responsible for the 1920 Haiyuan earthquake
.
many primary schools, forts, stockaded villages and temples were destroyed, killing 809 people. In Shandan County
more than 5,800 houses were destroyed and many cave dwellings collapsed, leaving 886 people dead.
The ground was extensively fissured, with fissures up to 14 km in length, 6–13 m wide and 7 m deep. A large landslide at Dongchuan buried several villages and blocked the road for a year.
and 8.0–8.3 on the surface wave magnitude
scale. The surface rupture caused by the earthquake was 23 km long.
Moment magnitude scale
The moment magnitude scale is used by seismologists to measure the size of earthquakes in terms of the energy released. The magnitude is based on the seismic moment of the earthquake, which is equal to the rigidity of the Earth multiplied by the average amount of slip on the fault and the size of...
event had an epicenter
Epicenter
The epicenter or epicentre is the point on the Earth's surface that is directly above the hypocenter or focus, the point where an earthquake or underground explosion originates...
near Gulang, Gansu
Gansu
' is a province located in the northwest of the People's Republic of China.It lies between the Tibetan and Huangtu plateaus, and borders Mongolia, Inner Mongolia, and Ningxia to the north, Xinjiang and Qinghai to the west, Sichuan to the south, and Shaanxi to the east...
in China
China
Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...
. There were more than 40,900 casualties. It was felt up to 700 km away.
Geology
The continental collisionContinental collision
Continental collision is a phenomenon of the plate tectonics of Earth that occurs at convergent boundaries. Continental collision is a variation on the fundamental process of subduction, whereby the subduction zone is destroyed, mountains produced, and two continents sutured together...
between the Indian Plate and the Eurasian Plate
Eurasian Plate
The Eurasian Plate is a tectonic plate which includes most of the continent of Eurasia , with the notable exceptions of the Indian subcontinent, the Arabian subcontinent, and the area east of the Chersky Range in East Siberia...
has formed the Himalayas
Himalayas
The Himalaya Range or Himalaya Mountains Sanskrit: Devanagari: हिमालय, literally "abode of snow"), usually called the Himalayas or Himalaya for short, is a mountain range in Asia, separating the Indian subcontinent from the Tibetan Plateau...
and the large uplifted area of the Tibetan Plateau
Tibetan Plateau
The Tibetan Plateau , also known as the Qinghai–Tibetan Plateau is a vast, elevated plateau in Central Asia covering most of the Tibet Autonomous Region and Qinghai, in addition to smaller portions of western Sichuan, southwestern Gansu, and northern Yunnan in Western China and Ladakh in...
. The northeastern part of Tibet is affected by the eastward lateral spreading of the Tibetan Plateau. This spreading is accommodated by a series of sinistral (left-lateral) strike-slip faults, including the Atyn Tagh, Haiuyan, Kunlun
Kunlun fault
The Kunlun fault is a strike slip fault to the north side of Tibet. Slippage along the long fault has occurred at a constant rate for the last 40,000 years. This has resulted in a cumulative offset of more than . The fault is seismically active, most recently causing the magnitude 7.8 2001 Kunlun...
and Xianshuihe faults, combined with thrusting
Thrust fault
A thrust fault is a type of fault, or break in the Earth's crust across which there has been relative movement, in which rocks of lower stratigraphic position are pushed up and over higher strata. They are often recognized because they place older rocks above younger...
on the Longmenshan fault
Longmenshan Fault
The Longmenshan Fault is a thrust fault which runs along the base of the Longmen Mountains in Sichuan province in southwestern China. The strike of the fault plane is approximately NE....
. The earthquake ruptured the complex thrust fault system in the Qilian Mountains transpressional zone, formed at a restraining bend on the Haiyuan fault. Another segment of the Haiyuan fault was responsible for the 1920 Haiyuan earthquake
1920 Haiyuan earthquake
1920 Haiyuan earthquake , was an earthquake that occurred on December 16, 1920. The epicenter was , in Haiyuan County, Ningxia Province, Republic of China...
.
Damage
In the area of greatest intensity, all cave dwellings and 90% of houses were destroyed. In Gulang, almost the only thing left standing was a 20 m long section of the city walls and some decorated archways. In Gulang county 4,000 people and 30,000 domestic animals were killed. In Wuwei, most of the city walls collapsed as did many temples, towers and civilian houses, 35,000 people and 200,000 horses and oxen were killed. In the area around YongchangYongchang County
Yongchang County is a county located in the province of Gansu in China. It belongs to the prefecture of Jinchang. The ancient North Silk Road passes through Yongchang County; numerous Han envoys were sent west along this trackway, some parties exceeding 100 members late in the first millennium BC...
many primary schools, forts, stockaded villages and temples were destroyed, killing 809 people. In Shandan County
Shandan County
Shandan County is a county in Gansu Province, the People's Republic of China. It is one of 58 counties of Gansu. It is part of the Zhangye prefecture, with the city of the same name being the prefecture seat. Its postal code is 734100, and in 1999 its population was 194,901 people. It is famous...
more than 5,800 houses were destroyed and many cave dwellings collapsed, leaving 886 people dead.
The ground was extensively fissured, with fissures up to 14 km in length, 6–13 m wide and 7 m deep. A large landslide at Dongchuan buried several villages and blocked the road for a year.
Characteristics
The magnitude of this earthquake has been variously calculated as 7.6 on the moment magnitude scaleMoment magnitude scale
The moment magnitude scale is used by seismologists to measure the size of earthquakes in terms of the energy released. The magnitude is based on the seismic moment of the earthquake, which is equal to the rigidity of the Earth multiplied by the average amount of slip on the fault and the size of...
and 8.0–8.3 on the surface wave magnitude
Surface wave magnitude
The surface wave magnitude scale is one of the magnitude scales used in seismology to describe the size of an earthquake. It is based on measurements in Rayleigh surface waves that travel primarily along the uppermost layers of the earth...
scale. The surface rupture caused by the earthquake was 23 km long.