Major earthquake threat from the Riasi fault in the Himalayas, says new study

By: Staff Reporter

A new study was conducted by Y. Gavillot, A. Meigs, D. Yule, R. Heermance, T. Rittenour, C. Madugo and M. Malik on ‘Shortening rate and Holocene surface rupture on the Riasi fault system in the Kashmir Himalaya: Active thrusting within the Northwest Himalayan orogenic wedge’ which was funded by National Science Foundation. The results of the study were then published by Geological Society of America Bulletin, 2016.

The study on new geologic mapping in the Himalayan Mountains of Kashmir between Pakistan and India suggests that the region is ripe for a major earthquake that could endanger the lives of as many as a million people.
The finding showed that the Riasi fault has been building up pressure for some time, suggesting that when it does release or “slip,” the resulting earthquake may be large – as much as magnitude 8.0 or greater.

Scientists have known about the Riasi fault in Kashmir, but it wasn’t thought to be as much as a threat as other, more active fault systems. However, following a magnitude 7.6 earthquake in 2005 on the nearby Balakot-Bagh fault – which was not considered particularly dangerous because it wasn’t on the plate boundary — researchers began scrutinizing other fault systems in the region.

There is direct evidence of some seismic activity on the fault, where the researchers could see displacement of Earth where an earthquake lifted one section of the fault five or more meters — possibly about 4,000 years ago. But the researchers don’t have much evidence as to how frequent major earthquakes occur on the fault, or when it may happen again.

The India tectonic plate is being sub-ducted beneath the Asia plate at a rate of 14 millimetres a year; the Riasi fault accounts for half of that but has no records of major earthquakes since about 4,000 years ago, indicating a major slip, and earthquake, is due.

Yann Gavillot, lead author of the study said that a major earthquake at the Riasi fault could have a major impact on Jammu, the Indian capital of the Indian state of Jammu and Kashmir, which has a population of about 1.5 million people. Another 700,000 people live in towns located right on the fault.

“There are also several dams on the Chenab River near the fault, and a major railroad that goes through or over dozens of tunnels, overpasses and bridges,” Gavillot said. “The potential for destruction is much greater than the 2005 earthquake.”  The 2005 Kashmir earthquake killed about 80,000 people in Pakistan and India.

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