David Booth of the British Geological Survey said he was very surprised the earthquake did not create a killer wave, as it was similar in force and depth to the devastating Dec. 26 quake, The Australian reported.
"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," the report quoted Booth as saying.
Booth said the previous quake had pushed the earth beneath the ocean shelf upward, wedging the Indian Oceanic plate beneath the edge of Sumatra and causing enormous pressure. When the pressure was released, it caused the front edge of Sumatra to leap upward by several meters.
"It generates the energy of tens of Hiroshimas, making the earth ring like a bell and squashing it like a football," Booth said.