A MASSIVE landslide caused by the October 8 earthquake has completely blocked two tributaries of the Jhelum river as it enters Azad Jammu and Kashmir from the Indian side and this could lead to possible flooding in the future, an image captured by NASA’s Terra spacecraft shows.

Acquired by the ‘Advanced Spaceborne Therman Emission and Reflection Radiometer’ on the spacecraft on Oct 11, the image shows a 30-kilometre wide region southeast of the earthquake’s epicentre between Muzaffarabad and Uri in Indian-controlled Kashmir in the Pir Panjal range.

The centre of the original image is at about 34 degrees, 13 minutes north and 73 degrees, 42 minutes east.

The 3-D image (which can be accessed http://photojournal.jpl.nasa.gov/jpegMod/PIA03028_modest.jpg) shows a large landslide (which is about 2 km x 1.5 km of collapsed hillside) which has blocked the flow of two rivers which drain into the Jhelum giving rise to two lakes. A US-based professor of geological sciences at the University of Colorado who has conducted extensive research into earthquake activity in the Himalayas, Roger Bilham, has details of the image on his webpage and says that ‘in the coming weeks and months the two streams will form upstream lakes until they breach the natural dam formed by the landslide.’

He adds that ‘depending on whether this is sooner or later, the size of the downstream flood could be modest or catastrophic’ in the downstream valley of Muzaffarabad. The image — with the Jhelum meandering in the top right portion heading towards Muzaffarabad and its confluence with the Neelum river — also shows a number of smaller landslides which the geologist says are a common feature of quakes in the Himalayas.

Prof Bilham, who led a team in 1999 to Nepal which corrected Mount Everest’s height by seven feet, makes the following observation: “Although the earthquake resulted in widespread devastation, it is doubtful that it has released more than one tenth of the cumulative elastic energy that has developed since the previous great earthquake in the region in 1555 or earlier.’ The quake of 1555 also hit the same area and was recorded by Nizamuddin Ahmed of Emperor Akbar’s court in his Tabakat-i-Akbari. Thousands were believed to have died in a catastrophic landslide.

The website also contains figures which were published in May 2005 showing the ‘slip potential’ along the Indian/Eurasian tectonic plates faultline as shown on a diagram about the potential for major earthquakes along an arc outlining the Himalayas north of Islamabad in the west and travelling eastward across northern India and along Nepal, Bhutan and northeastern Myanmar.

According to this, published four months before the Oct 8 temblor, earthquakes ranging between 7.4 and 8.6 on the Richter scale could occur along this arc at any time in the future. However, as geologists will be at pains to point out, predicting precisely when an earthquake may strike in terms of time and location is not possible.

As for the question whether such a large earthquake could trigger others in the region, Prof Bilham says that ‘probably not’ but then points out that quakes in the Himalayan are known to trigger others. However, he says, “we know of no great earthquake triggered days to months after a major earthquake in the same region.”