Friday, 1 June 2012

Earthquake near Karachi.

On Thursday 31 May 2012, at 8.35 pm local time (3.35 pm GMT), an Earthquake struck near Karachi, the capital of Sindh Province, Pakistan. The quake was recorded by the United States Geological Survey as measuring 4.0 on the Richter Scale and being centered 26 km southeast of the city, at a depth of 14.4 km. There are no reports of any damage or casualties, nor does the event appear to have caused any alarm to the city's 14 million residents; the local press has ignored the event, giving more coverage to the ongoing rescue attempts in the aftermath of Tuesday's earthquake in Italy.

Map showing the location of the 31 May quake. The Pink line is the boundary between the Eurasian and Indian Plates. USGS.

Karachi lies close to the boundary between the Indian and Eurasian Plates, which runs the length of Pakistan, passing to the north of Islamabad before turning east into Kashmir. This is a convergent boundary between two areas of continental plate, which is highly geologically active. Where two areas of oceanic crust collide, or one area of oceanic plate and one of continental plate, then one of the plates is subducted beneath the other, sinking into the Earth's interior. However continental plates do not subduct in this way, so collisions between two areas of continental plate result in crumpling of the crust, leading to uplift. On the boundary between the Indian and Eurasian Plates this has led to the formation of the Himalayas, the Hindu Kush mountains, the Tibetan Plateau and the mountain ranges of Central Asia.

This is far from being a smooth process, and leads to frequent Earthquakes, many of which cause severe problems for Pakistan and other countries on the border between the plates. In October 2005 a magnitude 7.6 quake centered 105 km north of Islamabad killed at least 86 000 people in Pakistan, India and Afghanistan, leaving an estimated 4 million homeless. In December 1974 another magnitude 6.2 quake to the north of Islamabad killed an estimated 5300 people, and quakes in 1945 and 1935 killed approximately 4000 and 30 000 people respectively.

See also Earthquake in southeast KazakhstanEarthquake in TajikstanEarthquake rattles Assam, northeast IndiaEarthquake in northwest Azerbaijan and Earthquakes on Sciency Thoughts YouTube.

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