An earthquake is the shaking of the surface of the Earth resulting from a sudden release of energy in the Earth's lithosphere that creates seismic waves. Earthquakes can range in intensity, from those that are so weak that they cannot be felt, to those violent enough to propel objects and people into the air and wreak destruction across entire cities. The seismic activity of an area is the frequency, type, and size of earthquakes experienced over a particular time period. The seismicity at a particular location in the Earth is the average rate of seismic energy release per unit volume. The word tremor is also used for non-earthquake seismic rumbling.
Strike-slip tectonics or wrench tectonics is the type of tectonics that is dominated by lateral (horizontal) movements within the Earth's crust. Where a zone of strike-slip tectonics forms the boundary between two tectonic plates, this is known as a transform or conservative plate boundary. Areas of strike-slip tectonics are characterised by particular deformation styles including: stepovers, Reidel shears, flower structures and strike-slip duplexes. Where the displacement along a zone of strike-slip deviates from parallelism with the zone itself, the style becomes either transpressional or transtensional depending on the sense of deviation. Strike-slip tectonics is characteristic of several geological environments, including oceanic and continental transform faults, zones of oblique collision and the deforming foreland of zones of continental collision.
In seismology, a supershear earthquake is an earthquake in which the propagation of the rupture along the fault surface occurs at speeds in excess of the seismic shear wave (S-wave) velocity. This causes an effect analogous to a sonic boom.
The Kunlun fault is a strike-slip fault to the north side of Tibet. Slippage along the 1,500 kilometres (930 mi) long fault has occurred at a constant rate for the last 40,000 years. This has resulted in a cumulative offset of more than 400 metres (1,300 ft). The fault is seismically active, most recently causing the magnitude 7.8 2001 Kunlun earthquake. It forms the northeastern boundary of the elongate wedge of the Tibetan Plateau known as the Bayan Har block.
The 1927 Gulang earthquake occurred at 6:32 a.m. on 22 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.
In seismology, a tsunami earthquake is an earthquake which triggers a tsunami of significantly greater magnitude, as measured by shorter-period seismic waves. The term was introduced by Japanese seismologist Hiroo Kanamori in 1972. Such events are a result of relatively slow rupture velocities. They are particularly dangerous as a large tsunami may arrive at a coastline with little or no warning.
In seismology, an earthquake rupture is the extent of slip that occurs during an earthquake in the Earth's crust. Earthquakes occur for many reasons that include: landslides, movement of magma in a volcano, the formation of a new fault, or, most commonly of all, a slip on an existing fault.
On December 7, 2015, an earthquake measuring 7.2 on the moment magnitude scale struck Tajikistan 105 km (65 mi) west of Murghab at 07:50 UTC at a depth of 26.0 km (16.2 mi). The earthquake was also felt in neighboring Xinjiang in China, India, Afghanistan, Pakistan and Kyrgyzstan.
The Haiyuan Fault is a major active intracontinental strike-slip (sinistral) fault in Central Asia.
The 2013 Craig, Alaska earthquake struck on January 5th, at 12:58 am (UTC–7) near the city of Craig and Hydaburg, on Prince of Wales Island. The Mw 7.5 earthquake came nearly three months after an Mw 7.8 quake struck Haida Gwaii on October 28, in 2012. The quake prompted a regional tsunami warning to British Columbia and Alaska, but it was later cancelled. Due to the remote location of the quake, there were no reports of casualties or damages.
The 1902 Turkestan earthquake devastated Xinjiang, China, near the Kyrgyzstan border. It occurred on August 22, 1902, at about 8:00 or 9:00 am local time with an epicenter near the Tien Shan mountains. The thrust earthquake measured 7.7 on the moment magnitude scale (Mw ) and initiated at a depth of 18 km (11 mi). The Tien Shan mountains is situated in a zone of complex convergence caused by the Indian–Eurasian plate interaction. This zone is actively deforming—accommodated by active thrust faults responsible for seismic activity. The mainshock was preceeded by an intense series of foreshocks in the years prior. Many aftershocks followed, several were larger than magnitude 6.0 and one measured magnitude 6.8–7.3. These aftershocks were recorded for three years. Additional shocks were recorded over a decade after the mainshock. An estimated 5,650–10,000 people were killed in the mainshock. Widespread destruction occurred—at least 30,000 homes were destroyed. Shaking was felt across an area of 927,000 km2 (358,000 sq mi). The effects of the earthquake led government officials to relieve victims of taxes and provide compensation.
The 1906 Manasi earthquake (玛纳斯地震), also known as the Manas earthquake occurred in the morning of December 23, 1906, at 02:21 UTC+8:00 local time or December 22, 18:21 UTC. It measured 8.0–8.3 on the moment magnitude scale and 8.3 on the surface-wave magnitude scale. The epicenter of this earthquake is located in Manas County, Xinjiang, China. An estimated 280–300 people died and another 1,000 more were injured by the earthquake.
The 1990 Gonghe earthquake occurred on April 26 at 17:37 China Standard Time in Hainan Tibetan Autonomous Prefecture, Qinghai Province. The mainshock had a surface wave magnitude of 7.0 Ms and a moment magnitude of 6.5 Mw . It was presaged by two foreshocks that struck merely seconds before the main earthquake. On the Mercalli intensity scale, the earthquake had a rating of IX (Violent).
The 2021 Maduo earthquake, also known as the 5.22 earthquake struck Madoi County in Qinghai Province, China on 22 May at 02:04 local time. The earthquake had a moment magnitude and surface-wave magnitude of 7.4. Highway bridges, roads and walls collapsed as a result of the earthquake. According to an anonymous source, at least 20 people were killed, 300 were injured, and 13 were missing. Officials stated that there were no deaths but 19 people sustained minor injuries. It was the strongest in China since 2008. It was assigned a maximum intensity of X in Machali, Maduo County on the China seismic intensity scale and Modified Mercalli intensity scale. This earthquake was preceded by another unrelated earthquake that occurred 5 hours earlier in Yunnan.
The 1995 Menglian earthquake or 1995 Myanmar–China earthquake occurred on 12 July at 05:46:43 local time in the Myanmar–China border region. The earthquake had an epicenter on the Myanmar side of the border, located in the mountainous region of Shan State. It registered 7.3 on the Chinese surface wave magnitude scale (Ms ) and 6.8 on the moment magnitude scale (Mw ). With a maximum Mercalli intensity assigned at VIII, the quake killed eleven people and left another 136 injured. Over 100,000 homes in both countries were destroyed and 42,000 seriously damaged. Some damage to structures were also reported in Chiang Mai and Chiang Rai, Thailand. The low death toll from this earthquake was attributed to an early warning issued prior to it happening. Precursor events including foreshocks and some seismic anomalies led to an evacuation of the area before the mainshock struck. It is thought to be one of the few successfully predicted earthquakes in history.
The 1979 Ghaenat earthquakes were a series of large earthquakes in Qaen County, Khorasan Province, northeast Iran, near the Afghanistan border. The first mainshock, known as the Korizan earthquake with a surface wave magnitude (Ms ) of 6.6 and moment magnitude (Mw ) of 6.8, struck on November 14, while the Ms 7.1 or Mw 7.2 Koli-Boniabad earthquake struck on November 27. The two mainshocks were assigned a maximum Modified Mercalli intensity of VIII (Severe) and X (Extreme), respectively. The earthquakes caused extensive damage throughout northeastern Iran, killing an estimated 297 to 440 people and left at least 279 injured.
The 1850 Xichang earthquake rocked Sichuan Province of the Qing dynasty 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 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.
