| UTC time | 2010-12-21 17:19:40 |
|---|---|
| ISC event | 600191591 |
| USGS-ANSS | ComCat |
| Local date | 21 December 2010 |
| Local time | 02:20 |
| Magnitude | 7.4 MW |
| Depth | 14.9 km (9 mi) |
| Epicenter | 26°51′58″N143°44′20″E / 26.866°N 143.739°E Coordinates: 26°51′58″N143°44′20″E / 26.866°N 143.739°E [1] |
| Areas affected | Japan |
| Tsunami | Yes |
| Aftershocks | 79 [2] |
| Casualties | None |
The 2010 Bonin Islands earthquake occurred on 21 December 2010 when a MW 7.4 earthquake struck off of the Bonin Islands, Japan. [1]
The moment magnitude scale is a measure of n earthquake's magnitude based on its seismic moment, expressed in terms of the familiar magnitudes of the original "Richter" magnitude scale.
The Bonin Islands, also known as the Ogasawara Islands, or, Yslas del Arzobispo, are an archipelago of over 30 subtropical and tropical islands, some 1,000 kilometres directly south of Tokyo, Japan. The name "Bonin Islands" comes from the Japanese word bunin, meaning "no people" or "uninhabited". The only inhabited islands of the group are Chichijima (父島), the seat of the municipal government, and Hahajima (母島).
The quake occurred at about 02:20 local time (17:20 UTC), about 155 kilometres (96 mi) east of the Bonin Islands, at a depth of around 15 km (9.3 mi). [3] [4] After the quake, the Japan Meteorological Agency issued a warning of a possible tsunami, capable of producing a wave of up to 2 metres (6.6 ft) high near the Bonin Islands, though milder for mainland Japan. [5] Residents of the Bonin Islands were advised to move towards higher ground, [4] and advisories were also issued for some provinces along Japan's Pacific coast. [6] Around 40 minutes after the initial quake, wave swells of up to 30 centimetres (12 in) were seen on the coast of the main Japanese island, though no tsunami waves were seen from the island of Chichi-jima. [5]
The Japan Meteorological Agency, JMA, is an agency of the Ministry of Land, Infrastructure, Transport and Tourism. It is charged with gathering and providing results for the public in Japan, that are obtained from data based on daily scientific observation and research into natural phenomena in the fields of meteorology, hydrology, seismology and volcanology, among other related scientific fields. Its headquarters is located in Chiyoda, Tokyo.
A tsunami or tidal wave,, also known as a seismic sea wave, is a series of waves in a water body caused by the displacement of a large volume of water, generally in an ocean or a large lake. Earthquakes, volcanic eruptions and other underwater explosions (including detonations, landslides, glacier calvings, meteorite impacts and other disturbances above or below water all have the potential to generate a tsunami. Unlike normal ocean waves, which are generated by wind, or tides, which are generated by the gravitational pull of the Moon and the Sun, a tsunami is generated by the displacement of water.
There were twenty-two M5.0+ aftershocks within six hours from the quake, including two with a magnitude of 5.6 that occurred at 1740 and 1741 UTC. [7] [8] [9] By 27 December, 79 M5.0+ aftershocks had occurred. [2]
No damage was initially reported from the quake, though an estimated 2,000 people were able to feel the tremble. [3] Around 170 residents of the Bonin Islands were evacuated to public buildings on Chichi-jima and Haha-jima. [5]