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 Kangding (), also called Tachienlu and Dartsedo (; ), is a county-level city and the seat of Garzê Tibetan Autonomous Prefecture in Sichuan province of Southwest China. Kangding is on the bank of the Dadu River and has been considered the histor ...

in the Garzê Tibetan Autonomous Prefecture,

Sichuan Sichuan (; zh, c=, labels=no, ; zh, p=Sìchuān; alternatively romanized as Szechuan or Szechwan; formerly also referred to as "West China" or "Western China" by Protestant missions) is a province in Southwest China occupying most of the ...

. 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.

Tectonic setting

Western

is situated at the edge 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 Ti ...

in a vast zone of complex continental deformation caused by the collision 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 ...

. As the thrusting of the Indian Plate beneath the Eurasian Plate along the

Himalayas The Himalayas, or Himalaya (; ; ), is a mountain range in Asia, separating the plains of the Indian subcontinent from the Tibetan Plateau. The range has some of the planet's highest peaks, including the very highest, Mount Everest. Over 100 ...

continues, the continental crust within the Eurasian Plate is actively uplifted and thickened, forming the Tibetan Plateau. As there are no active thrust structures within the plateau, compression is accommodated by

strike-slip 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 ...

motion along large structures including the Altyn Tagh Fault, Kunlun Fault,

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 ...

and

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 seismically ...

. Left-lateral

motion squeezes the crustal blocks of the Tibetan Plateau outwards, forcing it to move eastwards. Meanwhile, the strike-slip motion also results in east-west

extension Extension, extend or extended may refer to: Mathematics Logic or set theory * Axiom of extensionality * Extensible cardinal * Extension (model theory) * Extension (predicate logic), the set of tuples of values that satisfy the predicate * E ...

of the plateau, causing normal faults to break within the thickened crust.

Earthquake

The

is a 1,400-km-long active left-lateral

fault that accommodate the strike-slip motion in the Tibetan Plateau. The fault is one of the largest active intracontinental geological structure in the world. Beginning in 1893, at least 350 km of the fault length has ruptured in large successive earthquakes with magnitudes 6.5 or larger. Going back to the year 1700 to present-day, the fault has ruptured its entire 1,400 km length during large earthquakes.

Characteristics

The earthquake specifically ruptured the Zheduotang Fault; a segment of the Xianshuihe fault system. The left-lateral

rupture mechanism is consistent with movement along the fault system. A 43-km-long surface rupture is associated with the mainshock. In a November 2020 study published in the academic journal ''

Geological Journal Geological Journal is a peer-reviewed academic journal focusing on Geology Geology () is a branch of natural science concerned with Earth and other astronomical objects, the features or rocks of which it is composed, and the processes by w ...

'', the moment magnitude of the mainshock was evaluated at 7.0 . Previous studies have placed the surface wave and moment magnitudes at 7.5.

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 ...

after the 1955 earthquake increased seismic strain on the adjacent Selaha Fault, also part of the Xianshuihe fault system. In 2014, an earthquake measuring magnitudes 5.9 ruptured the Selaha Fault, releasing some of the strain. Since the 1955 quake, the Zheduotang Fault has accumulated enough strain to generate a magnitude 6.5–6.8 earthquake with the potiential to cause severe destruction.

Damage

Many

landslide 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 grade (slope), slope failures, mudflows, and debris flows. Landslides occur in a variety of ...

s were triggered and the ground

fissure A fissure is a long, narrow crack opening along the surface of Earth. The term is derived from the Latin word , which means 'cleft' or 'crack'. Fissures emerge in Earth's crust, on ice sheets and glaciers, and on volcanoes. Ground fissure A ...

d. Natural springs erupted water intensely or dried up. Spring water discolored after the quake. A total of 624 homes and temples were destroyed and 1,083 were damaged in Kangding. At least 70 people died and 217 were injured. Walls around the city toppled. Approximately 90% of the city's wooden-frame or adobe-constructed structures were destroyed. There were more than 30 landslides recorded, many of which blocked roads. In

Luding County Luding County (), also known via its Tibetan name as Chagsam or Jagsam ) is a county located in the southeast of the Garzê Tibetan Autonomous Prefecture in Sichuan province, China. Luding County covers an area of , and has a population of 86,234 ...

, shabby homes collapsed. Bridges, dams and ravines were seriously damaged or collapsed. Landslides affected an area of 4,416 km².

References

External links