  | |
| Local date | August 2, 1733 |
|---|---|
| Magnitude | Ms 7.75 |
| Epicenter | 26°12′N103°06′E / 26.2°N 103.1°E |
| Areas affected | Yunnan, China |
| Max. intensity | MMI X (Extreme) |
| Casualties | Dozens |
The 1733 Dongchuan earthquake affected Yunnan in China on August 2. The earthquake, which had an estimated surface-wave magnitude of 7.75, damaged homes across the province.
The Xianshuihe-Xiaojiang Fault is a major sinistral strike-slip fault system in China that runs along the southeastern edge of the Tibetan Plateau. It comprises the Xianshuihe, Anninghe-Zemuhe, Xiaojiang and Daliangshan faults. [1] The Xiaojiang Fault Zone represents the southeastern part of the Sichuan–Yunnan tectonic block's eastern boundary. The Sichuan–Yunnan block's southwestern margin is represented by the Jinshajiang and Red River faults. The Xiaojiang Fault Zone is seismically active, having been associated with over ten earthquakes greater than magnitude 6.0 since 1500. This includes a Ms 8.0 earthquake in 1833. [2]
The earthquake produced an 82 km (51 mi) surface rupture along the eastern segment of the northern Xiaojiang Fault Zone. It extended north–south from Shiliping to Tianba. It was also associated with a depression about 2–3 km (1.2–1.9 mi) long and 200–300 m (660–980 ft) across, bounded by vertical escarpments measuring 5–10 m (16–33 ft). Approximately 9 m (30 ft) of sinistral offset represented the largest strike-slip displacement from the earthquake. Vertical offsets were exclusively recorded south of the Dongchuan basin. Earthquakes of such magnitudes have an average return interval of 2,000 to 3,000 years. [2]
In Qiaojia, 16 civilians were killed by rockfalls when the town was destroyed. In a military camp, 50 soldiers escaped unhurt while one soldier died from a toppled beam at another campsite. Cui Naiyong, an official in Dongchuan, said about 40 people died in the larger towns of Bigu, Awang and Xiaojiang. He added that most homes, constructed of wood, rarely killed their inhabitants when they collapsed. In the Tangdan mines near Bigu, Cui reported a staggering death toll as each of the several hundred mines contained hundreds and thousands of workers at the time of the earthquake. These mines likely collapsed, killing those inside. [3] Only a handful of people managed to escape from the mines. At Huize, temples and administrative buildings were razed, nearly all fortification along the north and south city walls were destroyed. Forty percent of the battlements on the eastern and western part of the city were also destroyed. Landslides at Mushulang dammed the Yinghe River for three days. [4]
The 1927 Gulang earthquake occurred at 06:32 a.m. on 23 May. This 7.6 magnitude event had an epicenter near Gulang, Gansu in the Republic of China. There were 40,912 deaths. It was felt up to 700 km (435 mi) away.
The 1932 Changma earthquake occurred at 10:04:27 local time on 25 December. With an estimated magnitude of 7.6 on the surface wave magnitude scale, and a maximum felt intensity of X (Extreme) on the Mercalli intensity scale, the quake destroyed 1,167 houses and caused 275 to 70,000 deaths and 320 injuries.
The 1925 Dali earthquake occurred at 14:42 UTC on 16 March. It had an estimated magnitude of 7.0 on the surface wave magnitude scale and a maximum perceived intensity of at least IX (Violent) on the Mercalli intensity scale. It had an epicenter in the province of Yunnan in southern China and killed an estimated 5,000 people.
An earthquake occurred on 1 June 1786 in and around Kangding, in what is now China's Sichuan province. It had an estimated magnitude of about 7.75 and a maximum perceived intensity of X (Extreme) on the Mercalli intensity scale. The initial quake killed 435 people. After an aftershock ten days later, a further 100,000 died when a landslide dam collapsed across the Dadu river.
The Xianshuihe fault system or the Yushu-Ganzi-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 seismically active fault zones in China.
The Zhongwei-Tongxin fault or Tianjingshan fault is an arcuate sinistral (left-lateral) strike-slip zone, forming one of the major structures on the northeastern margin of Tibetan plateau. Six paleoearthquake events in the past 14,000 years have been recorded along the Zhongwei-Tongxin fault zone. Among the earthquakes recorded are the 1622 North Guyuan earthquake, which had a magnitude of 7.0 and mid-seismogenic depth of about 15 kilometres (9.3 mi), the 1709 Zhongwei earthquake, which had a magnitude of 7.5.
The 1988 Lancang–Gengma earthquakes, also known as the 11.6 earthquakes by the Chinese media were a pair of devastating seismic events that struck Lancang and Gengma counties, Yunnan, near the border with Shan State, Burma. The earthquake measured moment magnitude (Mw ) 7.0 and was followed 13 minutes later by a 6.9 Mw shock. 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 damage and economic losses. Moderately large aftershocks continued to rock the region, causing additional casualties and damage.
The 1973 Luhuo earthquake struck near the town of Zhaggo in Garzê Tibetan Autonomous Prefecture of Sichuan Province, China on February 6, 1973, with a magnitude of 7.6 Ms. The earthquake had a maximum intensity of X (Extreme) on the Modified Mercalli intensity scale. It resulted in between 2,175 and 2,204 deaths and a further 2,743 injuries. Serious and widespread destruction occurred in Luhuo County.
The 1739 Yinchuan–Pingluo earthquake rocked the northern Ningxia Hui Autonomous Region on January 3 with an epicenter in the prefecture-level city Shizuishan. The estimated magnitude 7.1–7.6 earthquake had a maximum intensity of XI on the Mercalli intensity scale, and killed about 50,000 residents and officials. It was widely felt; perceived in Shanxi, Shaanxi and Hebei provinces. Aftershocks persisted for more than two years with the largest being a 5.5 on February 13 that same year.
The Bayan Har block or Bayan Kola block is an elongate wedge-shaped block that forms part of the eastern Tibetan Plateau. It is bounded to the southeast by the Longmenshan Fault, a major thrust fault zone, which forms the active tectonic boundary between the plateau and the Sichuan Basin. To the northeast, the boundary is formed by the Kunlun and Minjiang Faults juxtaposing the block against the Eastern Kunlun-Qaidam block and to the southwest by the Xianshuihe fault system forms its boundary with the Qiangtang block. All of these are major left-lateral strike-slip fault zones. The block is currently moving to the southeast relative to the South China block.
The 2020 Qiaojia earthquake occurred in Yunnan, China, 42 km west of Zhaotong on May 18, 21:48 local time. The moment magnitude 5.1 quake occurred at a depth of 10 km. Various buildings were damaged, and one house collapsed in Zhaoyang District. Four people were killed while 24 people were injured.
The 2021 Luxian earthquake was a damaging seismic event occurring in the early hours of September 16 at 04:33 China Standard Time. The surface wave magnitude (Ms ) 6.0 or moment magnitude (Mw ) 5.4 earthquake struck at a shallow depth of 7.5 km and severe shaking in an area of 4,000 square kilometers was assigned a maximum intensity of VIII on the China seismic intensity scale. Three people were killed and 146 injured when the earthquake struck Lu County, Luzhou, Sichuan Province. At least 36,800 buildings were affected, 7,800 of them seriously damaged or completely destroyed, causing about a quarter of a billion dollars worth of damage.
The 1850 Xichang earthquake rocked Sichuan Province of Qing China on September 12. The earthquake which caused major damage in Xichang county had an estimated moment magnitude of 7.6–7.9 Mw and a surface wave magnitude of 7.5–7.7 Ms . An estimated 20,650 people died.
The 1923 Renda earthquake occurred on March 24 at 20:40 local time between the counties of Daofu and Luhuo in Sichuan, China. The estimated Ms 7.3 earthquake was assigned a maximum modified Mercalli intensity scale rating of X (Extreme). Severe damage occurred in Sichuan, killing an estimated 4,800 people.
The 1955 Zheduotang earthquake, also known as the Kangding earthquake occurred on April 14 at 09:29:02 local time near the city of Kangding in the Garzê Tibetan Autonomous Prefecture, Sichuan. The earthquake had a moment magnitude of 7.0 and a surface wave magnitude of 7.1 and struck at a depth of 10 km. Severe damage occurred in Kangding with the loss of 70 lives.
The region of Ningxia was struck by a major earthquake on the morning of 14 October 1709. It had an estimated magnitude of 7.5 Ms and a maximum felt intensity of X (extreme) on the Modified Mercalli intensity scale. The city of Zhongwei was badly damaged, including a section of the Great Wall. A total of 2,032 people were killed.
The 2003 Dayao earthquake occurred on July 21, at 23:16:33 CST. The epicenter of the moment magnitude 5.9 earthquake was in Dayao County in the mountainous area of central Yunnan, China. At least 19 people were killed, 644 were injured, and 8,406 families became homeless. The quake also caused $75 million USD in damage.
On April 11, 1870, a moment magnitude 7.3 earthquake struck Batang County in Sichuan, China. The earthquake had a maximum Modified Mercalli intensity of X (Extreme). The earthquake and a large fire resulted in between 2,300 and 5,000 fatalities.
The 1913 Eshan earthquake struck China's Yunnan Province on 21 December with a moment magnitude of 6.8 and maximum Mercalli intensity of IX (Violent). The shock devastated Eshan County; at least 942 people died and thousands of homes were destroyed. The earthquake ruptured along a section of the strike-slip Qujiang Fault.
On 23 December 1738 the province of Qinghai was struck by an earthquake with an estimated magnitude of 7.6 Mw. It ruptured the westernmost part of the Xianshuihe fault system, the Dangjiang segment. It led to 261–500 deaths.