The 1718 Tongwei–Gansu earthquake occurred on June 19, 1718 in

Tongwei County Tongwei County is located in the middle of Gansu province, the People's Republic of China, with east longitude between 104°57' and north latitude between 34°55' and 35°29'. It is under the administration of the prefecture-level city of Dingxi. ...

Gansu Province Gansu (, ; alternately romanized as Kansu) is a province in Northwest China. Its capital and largest city is Lanzhou, in the southeast part of the province. The seventh-largest administrative district by area at , Gansu lies between the Tibeta ...

Qing dynasty The Qing dynasty ( ), officially the Great Qing,, was a Manchu-led imperial dynasty of China and the last orthodox dynasty in Chinese history. It emerged from the Later Jin dynasty founded by the Jianzhou Jurchens, a Tungusic-speak ...

, present-day

China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's most populous country, with a population exceeding 1.4 billion, slightly ahead of India. China spans the equivalent of five time zones and ...

. The estimated

surface wave magnitude The surface wave magnitude (M_s) scale is one of the magnitude scales used in seismology to describe the size of an earthquake. It is based on measurements of Rayleigh surface waves that travel along the uppermost layers of the Earth. This ma ...

7.5 earthquake was assigned a maximum

Modified Mercalli intensity The Modified Mercalli intensity scale (MM, MMI, or MCS), developed from Giuseppe Mercalli's Mercalli intensity scale of 1902, is a seismic intensity scale used for measuring the intensity of shaking produced by an earthquake. It measures the eff ...

of X (''Extreme''), causing tremendous damage and killing 73,000 people.

Tectonic setting

The active

plate tectonic Plate tectonics (from the la, label=Late Latin, tectonicus, from the grc, τεκτονικός, lit=pertaining to building) is the generally accepted scientific theory that considers the Earth's lithosphere to comprise a number of large te ...

s of

located on the

Tibetan Plateau The Tibetan Plateau (, also known as the Qinghai–Tibet Plateau or the Qing–Zang Plateau () or as the Himalayan Plateau in India, is a vast elevated plateau located at the intersection of Central, South and East Asia covering most of the Ti ...

is dominated by the north–south

continental collision In geology, continental collision is a phenomenon of plate tectonics that occurs at convergent boundaries. Continental collision is a variation on the fundamental process of subduction, whereby the subduction zone is destroyed, mountains prod ...

of 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 mov ...

and

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 ...

. As the Indian Plate collides along a

convergent plate boundary A convergent boundary (also known as a destructive boundary) is an area on Earth where two or more lithospheric plates collide. One plate eventually slides beneath the other, a process known as subduction. The subduction zone can be defined by a ...

known as the

Main Himalayan Thrust The Main Himalayan Thrust (MHT) is a décollement under the Himalaya Range. This thrust fault follows a NW-SE strike, reminiscent of an arc, and gently dip towards the north, beneath the region. It is the largest active continental megathrust f ...

, it being of

continental crust Continental crust is the layer of igneous, sedimentary, and metamorphic rocks that forms the geological continents and the areas of shallow seabed close to their shores, known as continental shelves. This layer is sometimes called ''sial'' be ...

does not

subduct Subduction is a geological process in which the oceanic lithosphere is recycled into the Earth's mantle at convergent boundaries. Where the oceanic lithosphere of a tectonic plate converges with the less dense lithosphere of a second plate, the ...

, rather, it plows into the Eurasian Plate. This process severely deforms the Eurasian Plate, uplifting the crust, forming the

. The force of the Indian Plate converging pushes the Tibetan Plateau east, towards the

Sichuan Basin The Sichuan Basin (), formerly transliterated as the Szechwan Basin, sometimes called the Red Basin, is a lowland region in southwestern China. It is surrounded by mountains on all sides and is drained by the upper Yangtze River and its tributa ...

, forming another zone of collision. This collision and resulting crustal deformation of the Eurasian Plate is accommodated by the

Xianshuihe fault system The Xianshuihe fault system is a major active sinistral (left-lateral) strike-slip fault zone in southwestern China, at the eastern edge of the Tibetan Plateau. It has been responsible for many major earthquakes, and is one of the most seismicall ...

Haiyuan Fault The Haiyuan Fault is a major active intracontinental strike-slip (sinistral) fault in Central Asia. Tectonic setting The Haiyuan Fault forms part of the northeastern boundary of the Tibetan Plateau, which is an area of continental crust that ...

, Kunlun Fault,

Altyn Tagh fault The Altyn Tagh Fault (ATF) is a 2,000 km long, active, sinistral (left lateral) strike-slip fault that forms the northwestern boundary of the Tibetan Plateau with the Tarim Basin. It is one of the major sinistral strike-slip structures that t ...

, and

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. Motion on this fault is responsible for the uplift of th ...

. The pesence of active faults in Sichuan makes the region vulnerable to damaging earthquakes. The very deadly 2008 Sichuan earthquake occurred due to a

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 ...

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 ...

on the

. The 1920 Haiyuan and 1927 Gulang earthquakes occurred due to ruptures along the Haiyuan Fault.

Earthquake

The West Qinling Fault in the Tibetan plateau; an active left-lateral

strike-slip fault In geology, a fault is a planar fracture or discontinuity in a volume of rock across which there has been significant displacement as a result of rock-mass movements. Large faults within Earth's crust result from the action of plate tectonic ...

has been proposed as the source of the earthquake although there is no seismological evidence to prove this. In the past 300 years since the event, the fault has not produced any major earthquakes. Another proposed source is the adjacent Tongwei

although little is known about its associated seismological activity. No

surface ruptures A surface, as the term is most generally used, is the outermost or uppermost layer of a physical object or space. It is the portion or region of the object that can first be perceived by an observer using the senses of sight and touch, and is t ...

from the earthquake has been documented, suggesting it may be a

buried rupture earthquake In seismology, a buried rupture earthquake, or blind earthquake, is an earthquake which does not produce a visible offset in the ground along the fault (as opposed to a surface rupture earthquake, which does). When the fault in question is a th ...

Effects

All structures including government offices, schools, temples, and homes in Nanxiang were destroyed. It was reported that the only surviving structure was a portion of the brick city wall at the northeast of the city. Over 40,000 people were killed in the city. Another 30,000 people died in Yongning when massive

landslides Landslides, also known as landslips, are several forms of mass wasting that may include a wide range of ground movements, such as rockfalls, deep-seated slope failures, mudflows, and debris flows. Landslides occur in a variety of environments, ...

buried many homes in the area. Ground effects were severe; large fissures appeared, and the landscape was deformed. A large landslide completely buried the Yongning Ancient Town during the quake. Several mountain peaks including one at Jingning County detached and fell, damming a river, killing several thousand. In

Zhuanglang County Zhuanglang County is a rural county under the administration of the prefecture-level city of Pingliang in the east of Gansu Province, China. It borders Ningxia to the north, the Gansu county-level divisions of Huating City to the east, Zhangjiac ...

, a large hill suffered a landslide, resulting in thousands of deaths. Many

gate tower A gate tower (german: Torturm) is a tower built over or next to a major gateway. Usually it is part of a medieval fortification. This may be a town or city wall, fortress, castle or castle chapel. The gate tower may be built as a twin tower on ...

pavilion In architecture, ''pavilion'' has several meanings: * It may be a subsidiary building that is either positioned separately or as an attachment to a main building. Often it is associated with pleasure. In palaces and traditional mansions of Asia ...

s, and

battlement A battlement in defensive architecture, such as that of city walls or castles, comprises a parapet (i.e., a defensive low wall between chest-height and head-height), in which gaps or indentations, which are often rectangular, occur at interva ...

s in

Qin'an County Qin'an County () is a county in the east of Gansu province of the People's Republic of China. It is under the administration of the prefecture-level city of Tianshui. Its postal code is 741600, and in 1999 its population was 567,553 people. As of 2 ...

were destroyed. In

Tianshui Tianshui is the second-largest cities in Gansu, city in Gansu list of Chinese provinces, Province, China. The city is located in the southeast of the province, along the upper reaches of the Wei River and at the boundary of the Loess Plateau and ...

, the earthquake collapsed

Confucian Temple A temple of Confucius or Confucian temple is a temple for the veneration of Confucius and the sages and philosophers of Confucianism in Chinese folk religion and other East Asian religions. They were formerly the site of the administration of t ...

s and homes. Ground fissures and landslides killed some residents. Smaller fatality figures were reported across Gansu Province. The earthquake also affected

Shaanxi Shaanxi (alternatively Shensi, see #Name, § Name) is a landlocked Provinces of China, province of China. Officially part of Northwest China, it borders the province-level divisions of Shanxi (NE, E), Henan (E), Hubei (SE), Chongqing (S), Sichu ...

and

Henan Henan (; or ; ; alternatively Honan) is a landlocked province of China, in the central part of the country. Henan is often referred to as Zhongyuan or Zhongzhou (), which literally means "central plain" or "midland", although the name is al ...

provinces.

Landslides

The earthquake gained notable scientific attention due to the triggerering of over 300 large landslides. Most of the slides consisted of several meters of

loess Loess (, ; from german: Löss ) is a clastic, predominantly silt-sized sediment that is formed by the accumulation of wind-blown dust. Ten percent of Earth's land area is covered by loess or similar deposits. Loess is a periglacial or aeolian ...

and

mudstone Mudstone, a type of mudrock, is a fine-grained sedimentary rock whose original constituents were clays or muds. Mudstone is distinguished from '' shale'' by its lack of fissility (parallel layering).Blatt, H., and R.J. Tracy, 1996, ''Petrology. ...

deposits along steep mountainsides near the

Wei River The Wei River () is a major river in west-central China's Gansu and Shaanxi provinces. It is the largest tributary of the Yellow River and very important in the early development of Chinese civilization. The source of the Wei River is close to ...

. Three of the largest landslides in Pan'an,

Gangu County Gangu County () is a county in the southeast of Gansu province, the People's Republic of China. It is under the administration of Tianshui City and is the most populous county in Gansu. Its postal code is 741200, and in 1999 its population was 570 ...

, had a combined volume of 6.06 × 10⁸ m³. Locating the distribution of landslides using

Google Earth Google Earth is a computer program that renders a 3D computer graphics, 3D representation of Earth based primarily on satellite imagery. The program maps the Earth by superimposition, superimposing satellite images, aerial photography, and geog ...

found a dense concentration of occurrence along the Tongwei Fault.

References

{{DEFAULTSORT:Tongwei-Gansu earthquake 1718 disasters Earthquakes in Gansu Earthquakes in China 1718 in China 1718 in Asia Tongwei County Blind earthquakes 1718 in Tibet Zhuanglang County Jingning County, Gansu

Tectonic setting

Earthquake

Effects

Landslides

See also

References