MUMBAI, May 31: At exactly 6.59 pm today, an earthquake of slight intensity measuring 3.6 on the Richter scale rocked Mumbai and its outlying suburbs. According to the Colaba Weather Bureau, the epicentre of the quake was approximately 35 km away from Mumbai in the Thane-Kharghar belt (plotted at 19.04 latitude and 73.11 longitude).``Today's quake is quite small and is not a source of alarm or panic,'' Dr S K Arora, Chief Seismologist at the Bhabha Atomic Research Centre (BARC) told Express Newsline.
The tremors were felt more strongly in Thane city, Mumbra, Dombivli, Kalyan and Kulgaon. The impact seemed minimal in South Mumbai. Our correspondent from Thane adds: Mild tremors rocked various parts of Thane district and surrounding areas.
Confirming the tremors, district officials said there was no loss of life. Panic gripped the district as anxious callers quizzed newsmen and district officials about the tremors. In Thane city's Vartak Nagar locality, people rushed out of their housesimmediately after the tremor was felt.
However, the frequent minor quakes in and around the city have at least warranted the setting up of two independent studies. Dr Arora who is on a team set up by the state government last year to study the seismic zones in the city and state, added that the Thane-Jawahar-Khardi region had a history of minor earthquakes. The team which also comprises IIT Powai, Indian Institute of Geomagnetism, Mumbai is yet to submit its findings.
Earthquakes occur mainly due to weaknesses in the crust of the earth, called geological faults. When small readjustments occur in the upper layer of the brittle crust, quakes occur. While the earthquake that killed thousands in Latur five years ago, measured 6.3 on the Richter scale, yesterday's killer quake in Afghanistan measured 6.9 on the Richter scale.
Frequent quakes have been occurring in the Murbad-Jawahar belt. Tremors measuring upto four on the Richter scale were reported in this belt in 1996.Another project funded by the WorldBank through the Department of Science and Technology, the IIT's Earth Sciences Department and Pune University has also been studying seismic activity in and around the city.
While there is no method for any kind of prediction of quakes, efforts are on globally to develop methods to sense the earthquake preparatory zones by studying the development of many physical parameters that occur before a quake, Dr Arora said.
Experts feel that the sudden change of rivers from their natural course, could be one quake indicator. Many such river offsets have been noticed in Thane region around the Alu, Bhatsa, Tansa, Vaitarna and Surya river basins.In fact, the Bureau of Indian Standards is changing the seismic zonal map of this region to reflect a higher seismicity. Initial calculations show the entire region to be in Zone IV, with the possibility of quakes measuring 6 to 7 on the Richter scale. A 1972 map, on the other hand, places Mumbai on in Zone III, with the possibility of occasional shocks of 5 and 6 inmagnitude.
According to the widely accepted David Slemmons classification of earth faults, most of the faults running beneath Mumbai city fall in the category of local faults, which run to a few tens of kilometres and are capable of generating quakes ranging from 6.5 to 7 on the Richter scale.
The Aftershock
Calls poured in from all over the city soon after the tremors were felt, wanting to know the cause. Most believed it had to do with the nuclear explosions in Pokhran and Pakistan.
DATTATREYA DEVIDAS, BANDRA: Initially I thought some heavy vehicle was passing by. However, I felt the floor shaking and water bottle on the table rattling. I was then sure then it was an earthquake. SAYED, MANISH NAGAR, THANE: I was almost thrown off the bed by the quake. I feel the tremors must be the fallout of the nuclear tests at Pokhran.'' SUSHILA GOPALA KRISHNA, VILE PARLE: There was the sound of an explosion and my building trembled, I immediately knew it was an earthquake.''UNIDENTIFIED CALLER, MULUND (W): ``My television fell flat, shattering its tube. I blamed it on weak table legs until my wife, who was in the kitchen, said a bowl of milk being heated too had spilled on the gas stove and kitchen table. GAUTAM SHAH, MULUND: `The window panes of my house began to rattle...it lasted for three to four seconds. IVOR VAZ, BORIVLI: I was relaxing in my house, when I felt the ground shake at exactly 7.00 pm. But this tremor was nothing like the one in 1993.
FRANCIS MENEZES, KALINA: The whole room started shaking while I was watching television. AJAY KOTHI, THANE: I was watching the India-Kenya cricket match when I felt the vibrations. Vijay Sawant, Andheri (W): We were familiar with the drill since the Latur quake and so my wife and I ran out of the house. Intrigued, we asked some of our neighbours, who were on their way to the park, whether they had felt the tremor too. They said they would find out what had really happened before venturingthere. MAMTA SHAH,, who attended a sadhu satsangh at the Bandra Reclamation: We were so lost in meditation, we didn't feel a thing.Copyright © 1998 Indian Express Newspapers (Bombay) Ltd.
