'Downward earth movement failed to trigger tsunami'

David Booth of the British Geological Survey said he was "very surprised" that Monday's quake had not created a killer wave because it was almost similar in force and depth to the December 26 temblor that caused so much devastation.

"It appears Monday's quake caused a downward movement of the earth rather than the upwards jolt of the Boxing Day quake which caused a vertical displacement of the ocean floor, which creates the tsunami," Booth said.

"On Boxing Day, the quake pushed the earth beneath the ocean shelf upwards, wedging the Indian oceanic plate beneath the front edge of Sumatra," he said.

"This caused enormous pressure which, when released, made the front edge of Sumatra leap upwards by several metres."

"It generates the energy of tens of Hiroshimas, making the earth ring like a bell and squashing it like a football."

Booth added: "I'm very surprised there was no tsunami yesterday. The people of Asia are extremely fortunate the quake movement appears to have been downwards."