Western

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 ...

and southern

Shanxi Shanxi (; ; formerly romanised as Shansi) is a landlocked province of the People's Republic of China and is part of the North China region. The capital and largest city of the province is Taiyuan, while its next most populated prefecture-lev ...

in northern

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 ...

were struck by an earthquake of estimated magnitude 6.8 on 23 October 1815. The epicentre was in

Pinglu County Pinglu County () is a county in southern Shanxi province of China. It is under the administration of the prefecture-level city of Yuncheng and has a population of approximately 200,000. Pinglu is historically an agricultural county, producing appl ...

in southernmost Shanxi, which was the worse affected area. It had a maximum felt intensity of IX (''violent'') on the

Modified Mercalli scale 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 ...

. It caused the collapse of many houses and cave dwellings and led to the deaths of at least 13,000 people.

Tectonic setting

Shanxi and nearby provinces lie across the

Shanxi Rift System The Shanxi Rift System or Fen–Wei Rift System is a zone of active extensional tectonics that forms the eastern margin of the Ordos Block in northern China. The zone extends for at least and runs south-southwest to north-northeast. The individ ...

, an

active Active may refer to: Music * ''Active'' (album), a 1992 album by Casiopea * Active Records, a record label Ships * ''Active'' (ship), several commercial ships by that name * HMS ''Active'', the name of various ships of the British Royal ...

intraplate zone of

rift In geology, a rift is a linear zone where the lithosphere is being pulled apart and is an example of extensional tectonics. Typical rift features are a central linear downfaulted depression, called a graben, or more commonly a half-grabe ...

ing. The rift system forms the southern and eastern borders of the Ordos Block. This zone of

extensional tectonics Extensional tectonics is concerned with the structures formed by, and the tectonic processes associated with, the stretching of a planetary body's crust or lithosphere. Deformation styles The types of structure and the geometries formed depend on ...

is a reaction to the ongoing

collision In physics, a collision is any event in which two or more bodies exert forces on each other in a relatively short time. Although the most common use of the word ''collision'' refers to incidents in which two or more objects collide with great fo ...

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 ...

with 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 ...

. This has caused rotation of the Ordos and North China blocks leading to extensional displacement between them. At its southwestern end in

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 ...

the rift system has a west–east trend, before turning to a SSW–NNE trend through most of Shanxi. The individual rift basins and their bounding faults that make up the overall system mostly have a WSW–ENE to SW–NE trend. Ruptures along these rift faults have been the cause of many damaging earthquakes, including the 1303 Hongdong (>200,000 casualties) and 1556 Shaanxi (~830,000 casualties) earthquakes.

Earthquake

The estimated magnitude for this earthquake is about 6.8 . The earthquake is thought to have ruptured the Sanmenxia-lingbao Fault, with a

normal 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 ...

mechanism. An analysis of the evolution of stresses following the 1303 earthquake at Hongdong, suggest that most of the earthquakes in the rift system can be explained by progressive

coulomb stress transfer Coulomb stress transfer is a seismic-related geological process of stress changes to surrounding material caused by local discrete deformation events. Using mapped displacements of the Earth's surface during earthquakes, the computed Coulomb stress ...

, although the main earthquake to affect the 1815 rupture is judged to be the 1556 Shaanxi event, rather than any other earthquakes that affected the system in the intervening period.

Damage

Pinglu suffered the most severe damage, with the collapse of between 30% and 40% of houses and cave dwellings. Other structures were equally affected, including office buildings, prisons, storehouses and the city walls. 8,677 deaths were recorded in Maojin alone. In

Ruicheng Ruicheng County () is under the administration of the Yuncheng City, in the southwest of Shanxi province, China. It is the southernmost county-level division of Shanxi, with the Yellow River demarcating its border with the provinces of Henan to ...

town, damage was limited, but the surrounding villages were badly affected and about 1,600 people were killed. The tops of the city walls collapsed in Shanxian, as did many other buildings, with 1,340 deaths reported. Severe damage was also reported from Xiezhou (844 deaths), Yuxiang (683 deaths), Lingbao (>390 deaths), Anyi (>290 deaths) and

Yuncheng Yuncheng is the southernmost prefecture-level city in Shanxi province, People's Republic of China. It borders Linfen and Jincheng municipalities to the north and east, and Henan (Luoyang and Jiyuan to the east, Sanmenxia to the south) and Shaan ...

(>100) deaths).

References

{{Earthquakes in China Earthquakes in China 1815 earthquakes 1815 in China 1815 disasters in China