Studying megaquakes from monasteries

Over 3,000 people died and over 225,000 were made homeless in the 1906 San Francisco earthquake; the deadliest earthquake in the U.S. At the time, San Francisco had a population of 400,000. While these numbers are significant, an earthquake on the Indian and Eurasian plates has the potential to cause damage on a much larger scale, according to Dr. Roger Bilham.

Dr. Roger Bilham, a Professor of Geological Sciences at University of Colorado, Boulder, spoke about the potential risks for an earthquake in this region, particularly in the Kashmir valley in Northern India.

The Kashmir valley is located in between the Pir Pinjal Mountains and the greater Himalayas. If it were not for the Jhelum river exiting the valley, all of the waters entering in would fill it up into a lake. The valley also sits right on top of the Balpura fault. “People live on both sides of plates. As a consequence, earthquakes are very dangerous.” said Bilham.

Dr.Bilham said, “(We) know about earthquakes historically by destroyed ancient monasteries.” When these monasteries are hit, giant stone blocks will fall off and trap charcoal particles between the stone and the earth. These particles can then be dated when the stone is moved, and the year the earthquake happened can be calculated.

By further examining the earth around a fallen stone, geologists can determine the events that followed an earthquake; things such as floods. When speaking about one of the Kashmir temples, Dr. Bilham said, “We can tell the building was constructed then fell (in 883) trapping some particles.” The building also showed signs of flooding, as Dr. Bilham said, “The interesting part about a flood is that the temple is 25 meters above the valley floor.”

Due to evidence of flooding, it is theorized that a 100-mile long lake existed in the valley. The presence of the lake during medieval times helps to explain how the freestanding stone temples were built; the massive stones used to construct them would have been brought in on boats to their current locations.

Dr. Bilham further explained that a local folktale about the man who drained the lake all point to the its former existence. The origins of the lake are believed to be a landslide across the Jhelum river.

According to Dr. Bilham, for this to happen again, there only needs to be a landslide of about 15 meters high to produce the same level of water today that was seen in the medieval times.
Flood waters could potentially rise 50 centimeters a day for 10 days, then 10 centimeters a day for the next two months. But if a landslide occurred during the summer it could potentially rise water levels 30 to 40 centimeters a day. About 4 million people would need to be moved from agricultural land to safety if these floods occurred.

Due to the political animosity of India and Pakistan, it could prove very difficult to clear the landslide to return the Jhelum to its normal flow. The only way for India to reach the river is through the Kashmir valley, which will be flooded and inaccessible to the heavy machinery necessary to remove the landslide. The only way left will be through the Jhelum river valley through Pakistan.

Dr. Bilham said, “If you can’t reach a landslide you would be tempted to use explosives.” This in turn has potential to trigger a war, if Pakistan were to consider it an act of aggression. India and Pakistan have agreed that releasing flood waters is not an act of aggression, but they haven’t discussed having to use a bomb to do so.

When asked if he had approached government officials, Dr. Bilham responded, “Yes, they do not like what I have to say. We do not do the public a service by not thinking outside the box on what major earthquakes could come.” But according to Dr. Bilham, “Clearly there will be a future flood.”