New research funded by the National Science Foundation suggests that the Riasi fault in the Himalayan mountains of Kashmir between Pakistan and India is a prime location for a major earthquake that could threaten up to 1 million people.
Although scientists have known about the Riasi fault for years, it was not viewed as a threat in comparison to other active fault systems. However, after the magnitude 7.6 earthquake in 2005 on the nearby Balakot-Bagh fault that killed around 80,000 people in Pakistan and India, experts have been paying closer attention to the region.
The team discovered that the Riasi fault has been experiencing an increase in pressure for some time, and when it releases, the resulting earthquake could reach a magnitude of eight or higher.
"What we set out to learn was how much the fault has moved in the last tens of thousands of years, when it moved, and how different segments of the fault move," said Yann Gavillot, who conducted most of the research at Oregon State University (OSU) and is lead author of the study. "What we found was that the Riasi fault is one of the main active faults in Kashmir, but there is a lack of earthquakes in the more recent geologic record.
"The fault hasn't slipped for a long time, which means the potential for a large earthquake is strong," he added. "It's not a question of if it's going to happen. It's a matter of when."
The team observed some direct evidence of seismic activity on the fault but is still low on evidence of the frequency of major earthquakes on the fault. Furthermore, they have no indication when such an earthquake will occur.
"The Riasi fault isn't prominent on hazard maps for earthquake activity, but those maps are usually based more on the history of seismic activity rather than the potential for future events," said Andrew Meigs of OSU and co-author of the study. "In actuality, the lack of major earthquakes heightens the likelihood that seismic risk is high."
A major earthquake at the Riasi fault could lead to major damages in Jammu, the capital of the Indian state of Jammu and Kashmir. The state has a population of approximately 1.5 million people, with an additional 700,000 in towns directly 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 findings were published online April 27 in the Geological Society of America Bulletin.
