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Magnitude 7.8 earthquake hits Iran

Depth of temblor may have limited casualties

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A magnitude 7.8 earthquake rattled southeastern Iran April 16 at 3:14 p.m. local time. The quake struck about 80 kilometers east of the city of Khash in a thinly populated mountainous region near the border with Pakistan. The jolt was felt as far away as northern India and throughout parts of the Middle East.

The quake killed at least 13 people in Pakistan, Reuters reports. The death toll in Iran is unclear: An early account said 40 people died while some Iranian officials have reported there were no casualties. The jolt was felt as far away as northern India and throughout parts of the Middle East.

Iran sits in a seismically active region where three sections of Earth’s crust — the Arabian, Eurasian and Indian plates — meet and collide, forging the area’s mountains. Today’s event happened 82 kilometers beneath the surface in the northeast-moving Arabian plate, where the plate bends beneath the Eurasian plate and sinks into the upper mantle. The bending stretches the Arabian plate.

That stretching can trigger a temblor when one side of a fault slips down and away from the other side, says geophysicist Don Blakeman of the USGS Earthquake Information Center in Golden, Colo. This type of “normal” faulting unleashed a similar, magnitude 7.2 earthquake in January 2011 that hit 200 kilometers east of the latest quake.

The depth of today’s earthquake limited the death and destruction, says geophysicist Harley Benz, also of USGS. “Had it been shallower in the crust the damage would have been far more extensive.”

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