As rescuers try to reach thousands of people left homeless by a deadly 7.5 quake that rocked northern Afghanistan and Pakistan on Oct. 26, the event that killed at least 375 people and injured more than 2,000 is a reminder of the region's perilous geological nature.
The rugged region, long volatile due to armed conflicts, also often is the scene of terrifying earthquakes. Over the past century, it's been hit by 7 quakes with a magnitude of 7 or greater, according the U.S. Geological Survey.
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The active earthquake faults in the region result from the convergence of the India and Eurasia tectonic plates, the USGS website notes. The collision of those plates causes uplift, which has produced some of the highest mountain ranges in the world, including the Himalayan, the Karakoram, the Pamir and the Hindu Kush. The latest quake occurred in the midst of the latter range, about 28 miles north of Alaqahdari-ye Kiran wa Munjan, Afghanistan, and about 158 miles north-northeast of Kabul, the Aghan capital.
If there's one blessing in the terrible event, it's that the quake occurred deep under the earth, at least 125 miles down. That's much deeper than the 7.8 magnitude quake that devastated eastern Nepal in April, which originated a little more than three miles below the surface. That quake killed nearly 9,000 people and injured nearly 17,000, according to news reports. A 7.5 quake that struck the region in 2005 killed an estimated 86,000 people. That event occurred about 16 miles under the surface, according to USGS.
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The most recent quake's depth reduced the ground shaking that it caused, though those tremors were felt over a wide area.
The Hindu Kush mountains actually sit on a corner of the Indian plate, rather than being close to the spot where the two plates collide head-on. As a result of that process, the Himalayan mountains are thrust upwards as the India plate slips under the Eurasia plate at a rate of two inches per year, according to BBC News.