When the Earth Moved Kashmir
 
  • by Laura Naranjo
  • • design by Robert Simmon •
  • October 22, 2008
 

Nestled in the Himalaya Mountains, Kashmir inhabits a crossroads between the Middle East and Asia. Kashmir’s valleys and snow-clad peaks have historically hosted divergent cultures and housed scholarly learning centers. Its natural resources and complex heritage have attracted tourists and border disputes; the region is administered by the neighboring countries of Pakistan and India.

 

Originally published by Earth System Science Data and Services.

  Photograph of a summit above the Nubra Valley, Indian-controlled Kashmir.
 

Kashmir also inhabits another crossroads: It lies atop a web of active geological faults with underground dynamics that rival the complexities above ground. On October 8, 2005, one of the faults—places underground where the rocks are weak or cracked—gave way, resulting in a magnitude 7.6 earthquake. In a matter of seconds, the rugged terrain that lures travelers became a disaster zone that soon would host relief workers providing food and shelter, military rescue operations airlifting supplies, and scientists seeking to understand how the earthquake happened.

 

Kashmir is a land of high mountains, natural beauty, and ancient cultures. Although they appear timeless, the snowy peaks—and the people that live among them—continue to be shaped by the force of colliding continents. (Photograph ©2006 sanjoyg.)

  Map of Kashmir quake zone topography, faults, and epicenters.
 

After a major earthquake, scientists have traditionally relied on ground surveys to understand the damage. But satellite imagery is producing increasingly accurate ways to spot exposed faults and map deformation caused by earthquakes, especially in remote areas like Kashmir. What scientists learn by studying earthquake geology and post-earthquake deformation can advance what we know about earthquake dynamics and provide valuable information to relief organizations.

Anatomy of an Earthquake

Kashmir lies on the boundary of two colliding tectonic plates: the small Indian plate that underlies most of India and Pakistan, including much of Kashmir; and the vast Eurasian plate that underlies Europe, China, Russia, and much of the Middle East. Jean-Philippe Avouac, a geologist, a professor at the California Institute of Technology, and Director of Caltech’s Tectonics Observatory, studies Asian earthquakes and tectonics. Avouac said, “Northern India is being thrust under the Himalaya, and the mountains are being pushed up by this motion. It’s a small increment of deformation, which over millions of years has built the Himalaya range.” This slow-motion collision created one of the planet’s most active earthquake hotspots; as the plates collide, stress builds up in the fault zones where the plates meet.

 

On October 8, 2005, a magnitude 7.6 earthquake (large circle) and a series of aftershocks (small circles) struck Kashmir near the city of Muzaffarabad, Pakistan. The earthquakes occurred along the faults (red lines) that underlie the southern margin of the Himalaya. (NASA map by Robert Simmon, using SRTM elevation data and USGS earthquake locations.)

  Map of south asian tectonic plates.
 

Sudden and rapid releases of seismic stress can cause large earthquakes. And sometimes, an abrupt movement along a shallow fault can rupture the surface, as happened during the 2005 Kashmir earthquake. This surface rupture extended for seventy-five kilometers (forty-seven miles) and was a first among earthquakes in the Himalaya seismic zone. Robert Yeats, a geologist at Oregon State University, traveled to Pakistan after the Kashmir earthquake and witnessed the damage caused by the rupture firsthand. Yeats said, “In the known historic and recent records, not one of the earthquakes in the Himalaya has ever produced a surface rupture, not in Nepal, or India, or anywhere. This rupture was the first one.”

 

Muzaffarabad sits at the boundary between the slowly colliding Indian and Eurasian tectonic plates, both composed of thick continental crust. The pressure of the collision isn’t released gradually, but suddenly, when rocks that can no longer bear the stress crack. These forces make Kashmir one of the most earthquake-prone regions on Earth. (NASA map by Robert Simmon, from CleanTOPO2 data.)

  Earthquake fault trace cuts across a road in Balakot, Pakistan.
 

The Kashmir earthquake killed nearly 75,000 people, injured more than 100,000 people, and destroyed 3 million homes. Two towns that straddled the newly exposed fault suffered the most damage: Muzaffarabad and Balakot. In addition, the earthquake generated massive landslides that buried entire towns. Yeats said, “The upper side of the fault had a lot of landslides. Tens of thousands of people died because of landslides.”

 

The 2005 Kashmir earthquake actually split the Earth’s surface. Geologists call this event a surface rupture. The rupture crossed a road in Balakot, Pakistan, about 20 kilometers (12 miles) north of Muzaffarabad. In some areas, the earthquake shifted the ground more than 5 meters (16 feet). (Photograph ©2005, Robert Yeats.)

 
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