Tsunami is unlikely after 8.6-magnitude earthquake in Indonesia(Report from CNNIBN)

Tsunami is unlikely after 8.6-magnitude earthquake in Indonesia

The Indonesia earthquake that hit on Wednesday afternoon appears to have been astrike-slip earthquake. It is unlikely that there will be a devastating tsunami after Wednesday's 8.6-magnitude quake.

Tsunamis are generated by displacement of water. In 2004 Indian Ocean earthquake, a megathrust displaced a lot of water vertically, like so. The 2004 earthquake was almost purely strike-slip.

Strike-slip earthquakes are completely horizontal and there is no vertical displacement. Since the vertical displacement of this earthquake will be relatively limited, the amount of water displaced and therefore tsunami is also likely to be limited.

Strike-slip earthquakes are completely horizontal and there is no vertical displacement.

A devastating tsunami is not likely, at least not like the 2004 one but it is uncertain exactly how large a tsunami this earthquake may generate.

To generate a tsunami, you must have vertical uplift of water. It is not impossible for strike-slip earthquakes to generate vertical uplift of water, however.

If the strike-slip movement is towards the continental slope, there may still be some vertical offset.

If an earthquake occurs in an area with 100 m depth water and the strike-slip motion is towards shallower water and land. The huge 100 m stack of that water lying above the epicenter then moves towards land, too, where the water may only be 80 m deep. Suddenly you've just produced 20 m of vertical offset because you moved a 100 m deep stack of water to an area that's only 80 m deep. The strike-slip motion appears to be inESE oblique against Indonesia, though, it is still doubtful that this will be a devastating tsunami.

Tremors felt in many cities across South India

Chennai: Tremors were felt in Chennai, Bangalore, Thiruvananthapuram and several other cities across South India following the 8.6 magnitude earthquake in Indonesia.

Areas near Marina Beach Road in Chennai have been alerted in the wake of several coastal regions of Tamil Nadu, Andhra Pradesh and Andaman and Nicobar Islands being put on alert, police said.

There were no immediate reports of damage to property or loss of lives.

There were no immediate reports of damage to property or loss of lives.

In December 2004, killer Tsunami waves devastated several coastal areas of Tamil Nadu and hit Marina Beach here, causing heavy casualties.

In Kerala, people in Thiruvananthapuram and Kochi experienced slight tremors.

The country's IT capital Bangalore also experienced mild tremors, police said.

People rushed out of houses and high rise office buildings in panic in these cities.

Meanwhile, operations at Chennai Port has been suspended following the Tsunami alert, officials said.

Tsunami unlikely after 8.6 earthquake hits Indonesia

Jakarta: A tsunami watch was issued for countries across the Indian Ocean after a 8.6-magnitude earthquake, the eight worst in the last 100 years, hit waters off Indonesia on Wednesday, triggering widespread panic as residents along coastlines fled to high ground in cars and on the backs of motorcycles. But earthquake and tsunami experts say that quake was horizontal and not vertical, lessening the threat of tsunamis. The National Disaster Management Authority in India said that there was no likelihood of tsunami being formed anywhere in the Indian Ocean.

The US Geological Survey said the 8.6-magnitude quake was centered 20 miles (33 kilometers) beneath the ocean floor around 269 miles (434 kilometers) from Aceh's provincial capital.

The Pacific Tsunami Warning Center in Hawaii said a tsunami watch was in effect for Indonesia, India, Sri Lanka, Australia, Myanmar, Thailand, the Maldives and other Indian Ocean islands, Malaysia, Pakistan, Somalia, Oman, Iran, Bangladesh, Kenya, South Africa and Singapore.

According to earlier reports the tsunami waves were likely to be more than 6 metres high. A tsunami watch means there is the potential for a tsunami, not that one is imminent.

Said, an official at Indonesia's Meteorology and Geophysics Agency who goes by only one name, said a tsunami warning has been issued for cities all along the coast of Sumatra island. Residents in Banda Aceh are already moving to higher ground.

There was chaos in the streets, with fierce shaking continuing for nearly four minutes.

"I was in the shower on the fifth floor of my hotel," Timbang Pangaribuan told El Shinta radio from the city of Medan. "We all ran out. ... We're all standing outside now."

He said one guest was injured when he jumped from the window of his room.

The tremor was felt in Singapore, Thailand, Bangladesh, Malaysia and India. High-rise apartments and offices on Malaysia's west coast shook for at least a minute.

Thailand's National Disaster Warning Center issued an evacuation order to residents in six provinces along the country's west coast, including the popular tourist destinations of Phuket, Krabi and Phang-Nga. Indonesia agency also reported an aftershock of 6.5 quake Richter scale in Aceh.

Tremors were also felt in Kolkata, Chennai, Bangalore, Patna, Kochi, Thiruvananthapuram, Cuttack, Bhubaneshwar and several other cities on the eastern coast of India. India has also issued tsunami warning for coastal regions of Tamil Nadu, Andhra Pradesh, Andaman and Nicobar Islands following the earthquake.

The Chennai port has been shut down due to tsunami alert. National Disaster Response Force (NDRF) teams have already been rushed to Andaman and Nicobar Islands, coastal regions of Andhra Pradesh, Tamil Nadu and Kerala.

Indonesia straddles a series of fault lines that makes the vast island nation prone to volcanic and seismic activity.

A giant 9.1-magnitude quake off the country on Dec. 26, 2004, triggered a tsunami in the Indian Ocean that killed 230,000 people, nearly three quarter of them in Aceh.

(With additional information from Associated Press, Reuters and PTI)