Is it a Swarm?
- Data collected so far point to an “earthquake swarm”, a series of many (sometimes thousands) low-intensity earthquakes without a discernible main shock that can occur over weeks in active geothermal areas.
- A swarm lasting over 3 weeks killed 500 people on or around the Indonesian island of Lombok in July-August 2018.
- In India, sequences of low-intensity quakes are common in areas that have been hit previously, like Saurashtra in Gujarat and Koyna in Maharashtra.
- They are also seen in areas without a history of seismic activity.
- Many scientists have said that swarms are normal in peninsular India.
- Scientists have found no mining activity to explain the quakes, and have ruled out a small reservoir nearby as the caus
- Hence, they are pointing towards the swarm hypothesis.
Can There Be Other Possibilities?
- Seismologists are wary of drawing a definite conclusion without more data.
- They have not ruled out the possibility of either the quakes now subsiding or of a big one coming.
- Scientists still don’t know whether these earthquakes are a result of seismic activity, hydro-seismicity due to water percolation post-monsoon, or magmatic activity in the region.
