Frequent rumblings during the past week

HYDERABAD, DEC. 26. The insides of the earth have been rumbling frequently in the last one week. Though seismologists say it is nothing new, they point out that the earthquakes and their aftershocks listed below have been constantly above a magnitude of 3 on the Richter scale.

The United States Geological Survey (USGS) has listed on its website the prominent earthquakes, including those that struck the Indonesian island of Sumatra and the Andaman and Nicobar Islands in the India region. The biggest one in the list is the Sumatra killer, standing at 8.9 on the Richter scale, followed by one that measured 8.1 in the North Of Macquarie Island in the Southern Ocean, about halfway between Tasmania and Antarctica.

The earthquakes, apart from Indonesia and India, were located in Central Alaska, Taiwan, Japan, the Philippines, Western Turkey, Chile, Peru and Western Australia, to name a few.

USGS says that though it may seem that we are having more earthquakes, quakes of magnitude 7 or greater on the Richter scale are regular. The explanation it offers is that in the last 20 years, there has been an increase in the number of earthquakes that have been located due to the tremendous increase in the number of seismograph stations in the world. "In 1931, there were about 350 stations operating in the world; today, there are more than 8,000 stations," the Survey's website says. The list:

December 26

The Andaman Islands, India region: 5.8, 5.7, 5.7, 6.1 6.0 5.8 and 5.8 on the Richter scale; the Nicobar Islands: 7.3 and 6.0; Off W Coast Of Northern Sumatra: 5.9, 5.8 and 8.9; and Northern Sumatra, Indonesia: 5.9.

December 24

Java, Indonesia 4.6; Vanuatu Region 5.3; Fiji Region 5.1; and North Of Macquarie Island 5.5.

December 23

North Of Macquarie Island 8.1; and Central Alaska 4.5.

December 22

Southern East Pacific Rise 6.1; Off The Coast Of Oregon 4.9; South Sandwich Islands Region 4.5; Guatemala 4.3; Rota Region, Northern Mariana Islands 4.5; and Taiwan 4.3.

December 21

Halmahera, Indonesia 5.4; Southern Alaska 5.1; and Hokkaido, Japan Region 5.6.

December 20

Western Turkey 5.3; Cayman Islands Region 4.4; Galapagos Triple Junction Region 5.4; Central Mid-Atlantic Ridge 4.9; Izu Islands, Japan Region 4.7; Valparaiso, Chile 2.8; Tonga 4.9; Libertador O Higgins, Chile 3.0; Coquimbo, Chile 3.4; and Near The Coast Of Central Peru 5.0.

December 19

Valparaiso, Chile 4.0 and 3.6; Alaska Peninsula 5.2; Fiji Region 5.2; Mindanao, Philippines 5.4; South Of Panama 4.7; Panama 5.5; Coquimbo, Chile 3.6; Near The East Coast Of Honshu, Japan 5.3; Western Australia 2.9; Vanuatu Region 5.3; and Northern Peru 4.9.

Struck within 5 minutes

The earthquake hit the Indian coast within five minutes after it struck Sumatra. M. Kausalya in charge Seismic Observatory at the National Geographical Research Institute (NGRI) here, said the quake travelled at a speed of five kilometres per second.

Sumatra is around 2,500 km from the Indian coast.

She said the Andaman and Nicobar Islands experienced the maximum shocks, as they were situated 500 km away from the epicentre of the quake at Sumatra.

She said almost the entire east coast of India was affected though the worst hit were the southern parts of the coast. The aftershocks would continue for some days though with less magnitude. "The worst is over and the aftershocks would not be of high magnitude going by the nature of earthquakes and also the history of the quakes around the world", she said.

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