PALGHAR QUAKES

Although earlier part of Thane district,Palghar has its own identity which however does not rule out the impact of  earthquake there. Hence the fresh tremors recorded this morning must be taken note of.

The tremors ,of low intensity, measuring 2.9 richter are one of the dozen odd disturbances recorded by seismometer since February this year. Although the earthquake has not caused any damage to life and property,the administration is unlikely to take serious cognisance. According to experts the quakes are caused by swarms which are common in peninsular India.

Since November,  Palghar district has experienced dozens of small earthquakes. As on February 6, a seismometer located around 70 km from Palghar and operated by Gujarat’s Institute of Seismological Research (ISR), recorded 74 quakes, with 26 measuring between 1 and 1.9 on the moment magnitude scale (Mw), 39 measuring 2 and 2.9, and nine measuring over 3. This pattern of several small earthquakes occurring in a brief time-window is called an earthquake swarm. It cannot be dubbed as a foreshock or mainshock.

The epicentres of the current swarms haven’t seen such activity in the past. Why it is occurring now is a mystery. However, swarms are common in peninsular India and mostly harmless because of their low magnitude. In fact, a city called Jawhar in Palghar district has experienced swarms several times earlier. Another vulnerable region is Amaravati in Maharashtra, which saw swarm activity last August. Subsequently, the NCS set up seismometers in the region. They found that most earthquakes there were very shallow: they originated from within a few kilometres below the surface. Further, the tremors stopped soon after the monsoon. The researchers concluded that the swarms were related to the monsoon, and were attributable to a phenomenon called “hydro-seismicity.”

Whether the Palghar quakes are a swarm, however, will only be clear after they stop. Researchers will then categorise them based on the distribution of the magnitude. Because there is no way to predict whether such a large quake will follow, Palghar residents must be careful.

Although the experts rule out any overwhelming disaster,the district’s proximity to Mumbai and Thane that are densely populated,the local administrations monitor these tremors as precaution.