Tremors were felt across the country following the massive earthquake that rocked the northern tip of Sumatra in Indonesia. It triggered tsunami fears across the Indian Ocean nations including India.The quake measured 8.6 on the Richter scale.

While a tsunami warning was issued in India and 27 other countries, effects of the tremors felt in Chennai, Bengaluru, Kochi,

Kozhikode, Kolkata Thiruvananthapuram, Mangalore and Guwahti had panic-stricken people running out of their homes.

Six teams of the national disaster response force (NDRF) were kept in readiness at Chennai and an equal number were moved to Hindon airport to deal with any eventuality. The Indian navy and air force also placed their warships and aircraft on a state of high alert.

Bruce Pesgrave of the US Geological Survey explained that the impact of the quake was felt horizontally rather than vertically and hence had not displaced large volumes of water.

This was borne out by the findings of the scientists with the Hyderabad-based Indian National Centre for Ocean Information Service who said their instruments had recorded “sea level changes in Andamans as being higher than that in Ennore in Tamil Nadu which showed even smaller sea level changes.’

These could not be quantified as killer waves, it said. As a precautionary drill, the Andaman administration had moved people from Nicobar side to safer areas. Two IAF C-130 J Hercules aircraft with National Disaster Response Force teams and 10 tonnes of relief equipment are waiting at the Hindon airbase near Delhi for orders to take off for Port Blair.

Scores of NDRF personnel were aboard the aircraft. An IAF IL-76 transport aircraft is also positioned at Chandigarh for take-off for Chennai.

A meeting of the tri-services Integrated Defence Staff (IDS) was also held to monitor the situation with AN-32 transport and Dornier aircraft also being kept in readiness at Bengaluru, Thiruvanathapuram and Port Blair.

Home Secretary R K Singh claimed the government was ready to deal with any eventuality and there was no cause for panic along India's coastline.

World looks up to India for bulletins on tsunami

India on Wednesday proved its scientific prowess as a regional tsunami service provider (RTSP), exchanging bulletins with over two dozen countries in the Indian Ocean region on the tsunami wave movement in real time.

And Hyderabad, where RTSP India is located, played the key role in keeping several national tsunami early warning centres posted of the amplitude of tsunami waves as they traveled from the epicentre.

The warning was withdrawn, as the wave movement was not expected to trigger a tsunamigenic event. India became an RTSP nation on October 12, 2011 and Wednesday’s 8.6-magnitude earthquake in the Indonesian island of Sumatra was the first major tremor since. It offered a real firsthand experience for tsunami scientists in India, as the earthquake generated tsunami waves.

The tsunami team at the city-based Tsunami Early Warning Centre (TEWC) issued six public bulletins within three hours, recording three earthquakes each in the north Indian Ocean and off the west coast of northern Sumatra. Only one of them was of 8.5 magnitude, the rest being 7 or lower on the Richter scale.

“RTSP India monitored sea-level gauges near the epicentre and reported tsunami wave activity,” TEWC head Dr T. Srinivas Kumar said.

“It was the first major earthquake after the Indian Ocean tsunami mock drill on October 12, 2011. We shared real-time data with other RTSPs and countries in the Indian Ocean rim.”

Located at the Indian National Centre for Ocean Information Services (INCOIS) in Pragathinagar here, TEWC provided seismic and tsunamigenic information to Australia, Bangladesh, Comoros, France (La Reunion), India, Indonesia, Iran, Kenya, Madagascar, Malaysia, Maldives, Mauritius, Mozambique, Myanmar, Oman, Pakistan, Seychelles, Singapore, Sri Lanka, Tanzania, Thailand, Timor Leste, and Yemen.

Soon as the earthquake was recorded at a depth of 10 km off the west coast of northern Sumatra, an evaluation message from Hyderabad read: “Sea level observations have confirmed that a TSUNAMI WAS GENERATED.”

Following the message, Indian Ocean rim countries put their official machinery on high alert and tsunami sirens were sounded in a few countries, including Indonesia. The real-time wave movement was also provided to member-nations.

Senior earthquake scientist Dr RK Chadha said since the earthquake in Sumatra was of a high magnitude tremors were felt in several parts of South India, including Chennai, Vijayawada, Nellore, Kakinada, Visakhapatnam, Ongole and Machilipatnam.

When HAM tided over jams

Amateur radio (HAM) operators swung into action immediately when they heard news about earthquake and tsunami.

When all modes of communication, including cellphones got jammed due to hyper activity of the people, HAMs started to contact other operators in various parts of the state to help them to pass messages to their near and dear ones in the vicinity.

Some other operators were busy interacting with operators in the South East Asian countries to know the situation in their country.

Mr K. Rajesh (VU3RGK), an amateur radio operator, said that when he heard the news about earthquake and tsunami he logged on to 7050-megahertz in high frequency (HF), which HAMs in India use often to interact. “We tune to regular frequency to communicate in times of emergency and today we had about 25 HAMs across the Southern states operating in 7050 frequency communicating with each other in an attempt to help others,” he said.

Mr Rajesh pointed out that all HAMs stayed for four hours communicated with each other until the union government withdrew tsunami alert.

Mr D. Ramakrishnan (VU2DRK), another HAM operator, pointed out that during 2004 tsunami, HAMs played a major role to establish communication between Cuddalore collectorate and Chennai.

“Today I spoke to the meteorology department and extended our support to set up a HAM station to help them have a second line of communicate to interact with their offices in various government agencies across the country, besides communicating with other operators across the world,” he added.