At 14:52

local time Local time is the time observed in a specific locality. There is no canonical definition. Originally it was mean solar time, but since the introduction of time zones it is generally the time as determined by the time zone in effect, with dayligh ...

on 31 March 2002, an

earthquake An earthquake (also known as a quake, tremor or temblor) 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 ...

of magnitude 7.1 on the

moment magnitude scale 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 pap ...

hit

Taiwan Taiwan, officially the Republic of China (ROC), is a country in East Asia, at the junction of the East and South China Seas in the northwestern Pacific Ocean, with the People's Republic of China (PRC) to the northwest, Japan to the northe ...

. The

epicenter The epicenter, epicentre () or epicentrum in seismology is the point on the Earth's surface directly above a hypocenter or focus, the point where an earthquake or an underground explosion originates. Surface damage Before the instrumental pe ...

was offshore from Hualien, which was the most severely affected area with a maximum felt intensity of VII (''Very strong'') on the

Mercalli intensity 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 effe ...

. At least 5 deaths have been reported, with a further 213 injured.

Tectonic setting

has a history of strong earthquakes. The island is located within a complex zone of convergence between the

Philippine Sea Plate The Philippine Sea Plate or the Philippine Plate is a tectonic plate comprising oceanic lithosphere that lies beneath the Philippine Sea, to the east of the Philippines. Most segments of the Philippines, including northern Luzon, are part of ...

and

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 ...

. At the location of the earthquake, these plates converge at a rate of 78 mm per year. To the south of Taiwan,

oceanic crust Oceanic crust is the uppermost layer of the oceanic portion of the tectonic plates. It is composed of the upper oceanic crust, with pillow lavas and a dike complex, and the lower oceanic crust, composed of troctolite, gabbro and ultramafi ...

of the Eurasian Plate is

subducting Subduction is a geological process in which the oceanic lithosphere is recycled into the Earth's mantle at convergent boundaries. Where the oceanic lithosphere of a tectonic plate converges with the less dense lithosphere of a second plate, the ...

beneath the Philippine Sea Plate creating an

island arc Island arcs are long chains of active volcanoes with intense seismic activity found along convergent tectonic plate boundaries. Most island arcs originate on oceanic crust and have resulted from the descent of the lithosphere into the mantle alo ...

, the Luzon Arc. At Taiwan the oceanic crust has been entirely subducted and the arc is currently colliding with

continental crust Continental crust is the layer of igneous, sedimentary, and metamorphic rocks that forms the geological continents and the areas of shallow seabed close to their shores, known as continental shelves. This layer is sometimes called '' sial' ...

of the Eurasian Plate. To the north of Taiwan the Philippine Sea Plate is in contrast subducting northwards beneath the Eurasian Plate, forming the Ryukyu Arc. Within 200 km of this earthquake, there have been nine events of M≥7 during the preceding 40 years, including the M 7.7 1999 Jiji earthquake which resulted in over 2,400 deaths.

Earthquake

The earthquake had a magnitude of 7.1 with a hypocentral depth of 32.8 km. The depth and

focal mechanism The focal mechanism of an earthquake describes the deformation in the source region that generates the seismic waves. In the case of a fault-related event it refers to the orientation of the fault plane that slipped and the slip vector and ...

are consistent with moderate angle

reverse 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 tectoni ...

ing on the plate boundary interface that dips northwards beneath the western end of the Ryukyu arc.

Tsunami

A small tsunami (20 cm) was observed on

Yonaguni , one of the Yaeyama Islands, is the westernmost inhabited island of Japan, lying from the east coast of Taiwan, between the East China Sea and the Pacific Ocean proper. The island is administered as the town of Yonaguni, Yaeyama Gun, Okinawa ...

, in the

Yaeyama Islands The Yaeyama Islands (八重山列島 ''Yaeyama-rettō'', also 八重山諸島 ''Yaeyama-shotō'', Yaeyama: ''Yaima'', Yonaguni: ''Daama'', Okinawan: ''Yeema'', Northern Ryukyuan: ''Yapema'') are an archipelago in the southwest of Okinawa P ...

Damage

There was significant damage to buildings in the Taipei area, with three collapsing and the destruction of about 100 houses. An apartment building in the central part of the city collapsed, trapping 13 and injuring five. Cranes at the then Taipei World Financial Center, which was under construction, partly collapsed, killing five workers and injuring a further 10 people. At another construction site, scaffolding fell from a building. There was disruption to supplies of electricity, water and

gas Gas is one of the four fundamental states of matter (the others being solid, liquid, and plasma). A pure gas may be made up of individual atoms (e.g. a noble gas like neon), elemental molecules made from one type of atom (e.g. oxygen), or ...

. The Taipei metro train services were suspended due to a ruptured water pipe. Large cracks appeared in a city bridge. In Hualien, landslides blocked a highway and injured a child. The northeastern coastal areas were affected by many landslides. In total, there were 5 deaths and 213 people reported injured. Reports of shaking came as far as

Hong Kong Hong Kong ( (US) or (UK); , ), officially the Hong Kong Special Administrative Region of the People's Republic of China (abbr. Hong Kong SAR or HKSAR), is a city and special administrative region of China on the eastern Pearl River Delta i ...

References

External links