Earthquake Geology of Jammu and Kashmir

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Whenever a major earthquake hits any part of the planet Earth it always sends panic waves, and this has been going on for centuries. Jammu and Kashmir is one of the tectonic hotspots that has always been in news. The cause of earthquakes in this region is primarily because Indian plate is continuously trying to push harder to dive under the Eurasian plate, and in doing so it often breaks via earthquakes. Since the tectonic plates are solid and thus one cannot simply expect a solid to make a smooth dive under another solid. Think about rubbing of two rock units, thus the sliding journey will not be smooth, and friction will hold it tight, and once the applied forces overcome the frictional forces the movement will occur along a fracture, which we call a fault. Recently the Moment Magnitude (Mw) 7.8 earthquake ruptured a portion of this plate boundary fault on 25th April 2015 in Nepal in which we lost more than 15000 people. The fault is names as Main Frontal Thrust (MFT) fault, and it a megathrust fault that accommodates on an average some ~2 cm/year of the regional convergence between India and Eurasia plates. The total length of this fault is more than 2000 kilometer, and it marks the present day active plate boundary along which accumulated stress is occasionally released through medium to large magnitude earthquakes. Thus, it is not surprising that the ongoing collision has resulted in more than seven major earthquakes along the Himalayan arc in the past ~100 years.

Jammu and Kashmir sits on top of the magathrust fault, and it passes shallowly under Jammu city, however, no trace of this fault has been mapped on surface in this region yet, and thus it is assumed that it runs under as a blind structure (have not ruptured the surface). It largely controls the frontal-fold thrust belt in Jammu region, and has shaped the morphology of the entire region. The latest research demonstrates that there is a possibility of a major earthquake on this fault, which could happen anytime because currently in Jammu, and Kashmir region the tectonic stress is ripe to host such an earthquake. Recently another major fault, known as Riasi fault system, has been mapped in south of the Kashmir basin, and this fault had been seismically quite for some time, and thus there is a possibility that this fault could also host a major earthquake anytime soon. Importantly this fault merges at depth with the frontal blind thrust, and thus there is possibility that major earthquake could either occur on the Riasi fault system or the frontal fold-thrust belt, or both. Such an earthquake is estimated to be of (Mw > 8) or even bigger, a much bigger event than the Mw 7.6 earthquake that occurred on the Balakot- Bagh fault in Pakistan Azad Kashmir in 2005.

A well-documented major fault system, known as Kashmir basin fault, cuts through Kashmir basin, and has the potential to host Mw 7.6 or greater earthquake. This fault system has not been studies in details, thus there are greater uncertainties in understanding of this very fault. Although geomorphic studies clearly suggest that the fault is active, and has recently moved however, only a detailed work in the future will shed more light on its activity, and how much energy has been released through the fault. Since it is located north of the magathrust fault thus one would expect it to be a bit quitter than the frontal faults, but to answer this fundamental question we have to understand it in greater details.

A number of new and potentially active faults have also been mapped to the northwest and southwest of the basin, and most of these fault run parallel to the Muzaffarabad fault on which the deadly 2005 earthquake occurred and resulted in more than 80,000 deaths and lost/destruction of property worth millions. These faults could pose a lot of danger and could potentially nucleate earthquake in the near future.

Thus with our current understanding of the tectonic skeleton of the Jammu and Kashmir I think we are still at a very early stage of learning to understand how, what and why we have faults in this part of the world. And which fault will move in the future and how big. This is a difficult journey and hopefully we will solve it soon. It surely needs a lot of hard work and a dedicated team of experts to evaluate the possible causes of faulting in the region.

With many uncertainties we are still unable to understand how faults nucleate, propagate, and how stress accumulation on faults controls the portions of future earthquake hotspots. But what is certain is the fact that we are sitting on faults, and these giants often share a history of waking up unpredictably. Thus it is safe to conclude that major/mega earthquake disaster is Kashmir is unavoidable. And for a reliable seismic hazard and risk evaluation some detailed paleoseismological studies are extremely necessary to determine the current status of strain accumulation on faults/folds or fault-segments.

Further, our current knowledge about major earthquakes suggests that they generally do not follow a pattern, and occur randomly anytime, thus the time since the last great historical earthquake is posdibly of no real significance. This means that the concept of a rather regular return time between catastrophic earthquakes is probably not relevant for the Himalaya.

Please understand that the earthquake threat in Jammu and Kashmir is real and, it should not be taken lightly. Since the earthquake science is at a stage where scientists more or less understand the cause of earthquakes but are not very confident about the prediction of an incoming event. This means that there is a need to understand how to live with earthquakes without a successful prediction in sight. This can be achieved if we strictly abide by the strict construction standards, careful geological evaluation of building sites, and public education. This should be done now.

And in Jammu, and Kashmir there is a greater need to start a state of the art earthquake research facility for the security, and safety of the people.

 

 

 

 

 

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