Expect more tremors in city, warn experts

The city is getting more vulnerable to tremors. The tremor — measuring 2.6 on the Richter Scale — that hit Thane district at 1.07 am on Tuesday is the second in the area in the past two months and indicates the increased susceptibility of the Mumbai-Thane region, say experts.

The city is getting more vulnerable to tremors.

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The tremor — measuring 2.6 on the Richter Scale — that hit Thane district at 1.07 am on Tuesday is the second in the area in the past two months and indicates the increased susceptibility of the Mumbai-Thane region, say experts.

"The Thane tremors are significant as they indicate a possible shift of seismic activity to Mumbai island, from the northern region around Jawhar and Bhatsa and the eastern corridor between Kalyan and Panvel," said V. Subramanyan, former geology professor at IIT-Bombay.

Subramanyan had detected the three fault lines along the Thane, Panvel and Dharamtar creeks in 1986. The presence of these faults has been proved by mild tremors around these creeks in 1998 (in Ambhe, east of Taloja), 2002 (at Khairna, west of Taloja), 2005 (in Kalyan) and 2010 (in Thane and Mulund).

Seismic areas are classified into five zones, zone 5 representing the highest risk of earthquakes. Mumbai is in zone 3.

Though the recent tremors were mild, they signify that the earthquake energy in the region has crossed a threshold and is being felt on the surface, said Subramanyan.

India Meteorological Depart-ment officials said data needs to be analysed to check for changes in frequency to identify a trend.

Professor Ravi Sinha, civil engineering department, IIT-Bombay, said: "One cannot assume we need not worry about these tremors. A stronger quake is possible in Mumbai."

Experts said constructions should be strictly monitored for earthquake-resistant designs, especially those along the city's east coast such as Ghatkopar, Vidyavihar Bhandup, Mulund and Thane.