LiveScience
Location of the Chaman Fault in Pakistan.
Location of the Chaman Fault in Pakistan.
Credit: University of Houston

The powerful earthquake that hit Pakistan on Tuesday (Sept. 24) and killed more than 320 people struck along one of the most hazardous yet poorly studied tectonic plate boundaries in the world.

The magnitude-7.7 earthquake was likely centered on a southern strand of the Chaman Fault, said Shuhab Khan, a geoscientist at the University of Houston. In 1935, an earthquake on the northern Chaman Fault killed more than 30,000 people and destroyed the town of Quetta. It was one of the deadliest quakes ever in Southeast Asia.

Shaking from yesterday’s earthquake in Pakistan demolished homes in the Awaran district near the epicenter, according to news reports. The death toll will likely rise as survivors and emergency workers search the debris.

In the hours after the quake, a new island suddenly rose offshore in shallow seas near the town of Gwadar, about 230 miles (380 kilometers) southwest of the epicenter. Geologists with the Pakistan Navy have collected samples from the rocky pile, the Associated Press reported. From pictures and descriptions, many scientists think the mound is a mud volcano, which often erupt after strong earthquakes near the Arabian Sea. A second island has also been reported offshore of Ormara, about 170 miles (280 km) east of Gwadar, Geo News said.

“Other mud volcanoes have been triggered at this distance for similar size earthquakes,” Michael Manga, a geophysicist and expert on mud volcanoes at the University of California, Berkeley, told LiveScience’s OurAmazingPlanet.

Little known risk

The unexplained island may have focused unusual global attention on the earthquake, which hit in a region that frequently experiences devastating temblors. [Video: Island Appears After Pakistan Earthquake]

But despite the hazards faced by millions living near the Chaman Fault, a combination of geography and politics means the seismic zone remains little studied. The Taliban killed 10 climbers, including an American,  in northern Pakistan in June.

“Its location is in an area that is very difficult to do any traditional field work,” Khan told LiveScience’s OurAmazingPlanet. “I tried twice to submit proposals to [the National Science Foundation] and I got excellent reviews, but the review panel said I was risking my life to work in that area.”

But the National Academy of Sciences felt differently. With their support, Khan and his colleagues in Pakistan and at the University of Cincinnati are now studying the fault’s current and past movement. This will help the researchers forecast future earthquake risk.

“This fault has had very little work and no paleoseismology,” Khan said. “It is really important.”

Complex collision zone

Pakistan’s deadly earthquakes owe their birth to the juncture of three colliding tectonic plates: Indian, Eurasian and Arabian. The Indian and Eurasian plates grind past each other along the Chaman Fault, triggering destructive temblors.

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People walk on an island.

A magnitude 7.7 earthquake struck a remote part of Pakistan with enough force to create a small island.

Photograph from Gwadar Government/AP

Brian Clark Howard

National Geographic

Published September 25, 2013

On Tuesday, a 7.7-magnitude earthquake struck a remote part of western Pakistan, killing more than 260 people and displacing hundreds of thousands. It also triggered formation of a new island off the coast, which has quickly become a global curiosity.

But scientists say the island won’t last long.

“It’s a transient feature,” said Bill Barnhart, a research geophysicist with the U.S. Geological Survey. “It will probably be gone within a couple of months. It’s just a big pile of mud that was on the seafloor that got pushed up.”

Indeed, such islands are formed by so-called mud volcanoes, which occur around the world, and Barnhart and other scientists suspect that’s what we’re seeing off the Pakistani coast.

News organizations have reported that the Pakistani island suddenly appeared near the port of Gwadar after the quake. The island is about 60 to 70 feet (18 to 21 meters) high, up to 300 feet (91 meters) wide, and up to 120 feet (37 meters) long, reports the AFP.

Media reports have located the new island at just a few paces to up to two kilometers off the coast of Pakistan. It is about 250 miles (400 kilometers) from the epicenter of the earthquake.

Map by National Geographic maps.

The island appears to be primarily made out of mud from the seafloor, although photos show rocks as well, Barnhart told National Geographic. He has has been studying images and media accounts of the new island from his lab in Golden, Colorado.

“It brought up a dead octopus, and people have been picking up fish on [the island],” he said.

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