On May 21, 2021, a 6.1 magnitude earthquake strucked the

Dali City Dali City () is the county-level seat of the Dali Bai Autonomous Prefecture in northwestern Yunnan. Dali City is administered through 12 township-level districts, two of which are also commonly referred to as Dali. Xiaguan () formerly ...

Yunnan Yunnan , () is a landlocked province in the southwest of the People's Republic of China. The province spans approximately and has a population of 48.3 million (as of 2018). The capital of the province is Kunming. The province borders the ...

, China, at a depth of 10.0 km. Three people died during the quake, while another 32 were injured. The earthquake was referred by the Chinese media as the 5.21 earthquake or 2021 Yangbi earthquake.

Tectonic setting

Yunnan lies at the southeastern boundary of 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 T ...

where

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 tecton ...

s accommodate crustal rotation resulting from deformation caused by 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 ...

between 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 m ...

and 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 ...

which formed the Himalayas and the Tibetan Plateau. The presence of

active fault An active fault is a fault that is likely to become the source of another earthquake sometime in the future. Geologists commonly consider faults to be active if there has been movement observed or evidence of seismic activity during the last 10, ...

s make the region prone to moderate to large earthquakes. Major events in Yunnan Province have occurred in

1833 Events January–March * January 3 – Reassertion of British sovereignty over the Falkland Islands in the South Atlantic. * February 6 – His Royal Highness Prince Otto Friedrich Ludwig of Bavaria assumes the title His Majesty Othon t ...

1974 Major events in 1974 include the aftermath of the 1973 oil crisis and the resignation of President of the United States, United States President Richard Nixon following the Watergate scandal. In the Middle East, the aftermath of the 1973 Yom K ...

1976 Events January * January 3 – The International Covenant on Economic, Social and Cultural Rights enters into force. * January 5 – The Pol Pot regime proclaims a new constitution for Democratic Kampuchea. * January 11 – The 1976 Phil ...

, 1988 and

2014 File:2014 Events Collage.png, From top left, clockwise: Stocking up supplies and personal protective equipment (PPE) for the Western African Ebola virus epidemic; Citizens examining the ruins after the Chibok schoolgirls kidnapping; Bundles of wat ...

. The nearest active faults in Dali City are the Xiaojiang Fault and

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 ...

. The Red River Fault caused two deadly earthquakes in 1925 near Dali and another in 1970 in Tonghai county.

Earthquake

The earthquake was the result of strike-slip faulting at a shallow depth. It had a maximum intensity ranging from VII (''Very Strong'') to VIII (''Severe'') on the Mercalli intensity scale. According to 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, ...

(USGS), the earthquake had a

moment magnitude 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 ...

of 6.1 while the

China Earthquake Networks Center The China Earthquake Networks Center (CENC; ) is an institution under the China Earthquake Administration. Established on October 18, 2004. It is one of the most important hubs of China's earthquake disaster reduction network and the basis of inf ...

(CENC) and

China Earthquake Administration The China Earthquake Administration (CEA), () is mandated by the ''Law of the People's Republic of China on Protecting Against and Mitigating Earthquake Disasters of PRC'' to enforce the earthquake administration in the nation under the administrati ...

(CEA) measured the earthquake at 6.4 on the

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 ...

scale. The depth of focus is reported to be 10 km by the USGS and 8 km by the CEA. Several hours later, an unrelated Mw 7.3 earthquake struck Southern Qinghai province that was felt in the area.

Casualties

Two fatalities were reported in Yangbi County while another three suffered serious injuries. One of the victims, a truck driver, was killed as a result of a rockfall while another woman in a trapped vehicle had leg injuries. A total of 26 people in the county were injured. In Yongping County, the earthquake killed one person, and left another injured. A 28th injury was reported in Dali City. On May 22, a press release said the number of people injured was brought to 32, with seven in serious condition. Five of the seven who are seriously injured suffered trauma to the head and chest, as well as bone fractures.

Damage

The earthquake damaged some 12,882 homes in

Yangbi County Yangbi Yi Autonomous County () is a county of the Dali Bai Autonomous Prefecture located 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 ...

References

2021 disasters in China 2021 earthquakes Earthquakes in Yunnan 2021 earthquakes in Asia {{China-hist-stub

Tectonic setting

Earthquake

Casualties

Damage

See also

References