‘Earthquake Island’ Appears Off Coast of Pakistan

On September 24, 2013, over 500 were killed when a strong 7.7 magnitude earthquake struck the province of Balochistan in southwest Pakistan. Two days later a new island unexpectedly emerged from the sea roughly one kilometer (0.6 miles) from shore near the city of Gwadar.

Source: Pakistan National Institute of Oceanography via NASA

The island, now named Zalzala Koh (Arabic for earthquake mountain), is likely a mud volcano. It measures about 250–300 ft (76–91 m) in length and 60–70 ft (15–20 m) in height and although the surface is a mixture of mud, sand, and rock, it is solid enough for people to walk on.

Why do these form? Mud volcanoes emerge during earthquakes because the vibrations release mud and water trapped beneath the seafloor. When it erupted, compact portions of the sandy seafloor were thrusted upward along with mud resulting of either trapped gases escaping or subsurface water violently being expelled.

Before & After: no island is April 17, 2013, compared to a new satellite image from Sept. 26, 2013. © NASA

Before & After: no island is visible on April 17, 2013, compared to a new satellite image from Sept. 26, 2013. © NASA

Visitors have been flocking to the new land mass by boat since its emergence, exploring and collecting stones as souvenirs. Water continues to bubble as gases discharge along the edges of the island. A local journalist, Bahram Baloch, watched as residents held flames to fissures emitting gas with caught fire. “We put the fire out in the end, but it was quite a hassle. Not even the water could kill it, unless one poured buckets over it,” Mr. Baloch said.

“There were dead fish on the surface. And on one side we could hear the hissing sound of the escaping gas.”

© REUTERS/Stringer

© REUTERS/Stringer

Geologists say it’s a result of the continuing movement of continents relative to each other across the oceans (continental drift). This very slow action caused the Indian sub-continent to collide with Eurasia, creating fault-lines, some of which run through the Pakistan coast. This same process gradually pushes India into Asia, forming the Himalayas which are still rising to this day.

How do mud volcanoes form? Rashid Tabrez, the director-general of the Karachi-based National Institute of Oceanography, says “when the plates along the fault-lines move, they create heat and the expanding gas blasts through the fissures in the earth’s crust, propelling the entire sea floor to the surface.”

Similar islands have burbled up along this coastline after earthquakes in 1945 and 1968, which locals still recall. But each soon disappeared in less than a year as a result of mechanical (physical) weathering, eroded by water movement (waves) and monsoons. Over the following year, Zalzala Koh will likely to undergo the same vanishing act, washing away into the Arabian Sea.

Source: http://www.bbc.co.uk/news/world-asia-24272552


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