Causes of Pakistani Earth Quake & Tsunami - Indian Plate slowly moving North

Causes of Pakistani Earth Quake & Tsunami - Indian Plate slowly moving North

The earth's continents rest upon large plates of rock that are slowly moving around the surface of the earth. For millions of years, the Indian subcontinent has been slowly moving north towards Europe and Asia (Eurasia). About 40-50 million years ago (mya), India slammed into Eurasia. Because both India and Eurasia were continents the Eurasia crust crumpled upwards, creating the Himalayan mountains. The leading edge of India was eventually forced underneath the continent in a process geologists call subduction. This movement is still happening today. However, as India continues to move slowly north, it gets hung up and energy builds. When enough energy builds up, there are short bursts of movement, releasing this massive energy and shaking and buckling the ground in what we call an earthquake.

http://classic.mountainzone.com/everest/graphics/s-map.gif
The Indian plate is being forced northward under the Asian continent. The resulting earthquakes -- among the most destructive on the planet -- formed the Himalay.


The region has a long history of seismic activity because it is located on the Indian plate, a piece of the earth's crust moving north at the rate of some 40 millimeters per year. As the plate collides into and slips under the massive Eurasian plate to the north, it lifts the world's highest mountain ranges, the Himalayas, even higher. But major fault lines exist at the plate's edge, where sudden jolts have wreaked massive devastation.

The 9.0 magnitude quake that caused the 2004 Indian Ocean tsunami occurred on the sea floor, where the India plate rubs against the Burma plate.


http://www.eas.purdue.edu/~braile/edumod/platepuzz/platepuzz_files/image007.jpg

http://www.earthquakes.bgs.ac.uk/pakistan_08102005.htm




SEISMIC ALERT: PAKISTAN 8 OCTOBER 2005 03:50 UTC 7.6 MW


DATE : 08 October 2005 ORIGIN TIME : 03:50 38s UTCLAT/LONG : 34.43° North / 73.54° EastDEPTH : 10 kmMAGNITUDE : 7.6 MwLOCALITY : Northern Pakistan, (95 km NNE of Islamabad)

Latest reports indicate that at least 30,000 people may have been killed in Pakistan. Extensive damage has occurred throughout Kashmir and other northern areas. Numerous towns have been severely affected and some villages completely destroyed. This earthquake has had an impact on Pakistan, northern India and parts of Afghanistan.

Above: Map showing the seismicity of Northern Pakistan (magnitudes above 6.0) since 1896.


This earthquake occurred as a result of the collision of the Indian sub-continent with Eurasia. India is moving north at a rate of around 4 cm/year. The collision causes compression and uplift, forming the Himalaya, Karakoram and Hindu Kush mountain ranges. Compression is also accommodated by slip on a number of major thrust fault zones, resulting in earthquakes over a wide area along the collision zone. The earthquake on 8 October probably occurred on one of these thrust faults. Large destructive earthquakes have struck Kashmir in the past. In 1905, an earthquake on the Kashmir-India border region killed 19,000 people. More recently, a magnitude 6.3 earthquake in 1981 in northwest Kashmir killed over 200 people. Pakistan’s most damaging earthquake occurred near the city of Quetta in 1935, killing 30,000 people.


Above: Map showing aftershocks recorded since the main event of 8 October 2005.

Above: Seismograms of the Pakistan earthquake of 8 October 2005 as recorded on BGS seismometers.


On land, a 5.8 magnitude quake in northern Afghanistan's Hindu Kush mountains in 2002 killed about 700 people, and in western India in 2001, a 7.6 magnitude earthquake killed at least 11,000 people in Gujarat.
US Geologic Survey image shows the approximate epicenter of the October 8 quake in Pakistan
Massive quakes on the Indian subcontinent were also reported in 1935, when some 35,000 people were estimated killed in a tremor in western Pakistan; and in 1905, when nearly 20,000 died in a 7.9 magnitude quake in northern India.

An earthquake's magnitude indicates how much energy it releases, but other factors affect the extent of its devastation, including where tremors strike, the type of terrain around them, and how deep within the earth they occur.


In 1974, a magnitude 6.2 earthquake in the same region as Saturday's tremor killed more than 5,000 people.

Some seismologists say because Saturday's magnitude 7.6 quake appears to have been very shallow, with much of the violent activity occurring near the earth's surface, it could be more damaging compared to other quakes of similar magnitude.




Thats all for now folks!

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