New Islands Formed in Pakistan Last Week
The French Pleiades satellite mapped the muddy hill's dimensions, which measure 576.4 feet (175.7 meters) long by 524.9 feet (160 m) wide. Aerial photos from Pakistan's National Institute of Oceanography suggest the gray-colored mound is about 60 to 70 feet (15 to 20 m) tall. [Gallery: Amazing Images of Pakistan's Earthquake Island]
The new island could be a mud volcano. Mud volcanoes form when hot water underground mixes with sediments and gases such as methane and carbon dioxide. If the noxious slurry finds a release valve, such as a crack opened by earthquake shaking, a mud volcano erupts, said James Hein, a senior scientist with the U.S. Geological Survey in Santa Cruz, Calif, said in an earlier interview. Geologists from the Pakistan Navy report that Zalzala Koh is releasing flammable gas. But seafloor sediments commonly hold methane-producing bacteria, so the possible methane coming from the island isn't a clincher to its identity.
Shaking from the powerful Sept. 24 earthquake could have also loosened the seafloor sediments offshore of Pakistan, jiggling them like jelly. The great rivers coming down from the Himalayas dump tons of water-saturated sediment into the Arabian Sea every year. The new island could be a gigantic example of a liquefaction blow, when seismic shaking makes saturated sediments act like liquid and trapped water suddenly escapes, Michael Manga, a geophysicist at the University of California, Berkeley, told LiveScience last week.