WASHINGTON - Strong aftershocks from the Indonesian earthquake will be felt for "weeks and months" but more killer-magnitude tremblers and deadly tsunamis were unlikely, a geophysicist with the US Geological Survey said on Wednesday.
Waverly Person, a USGS director, said he anticipates repeated and at times powerful aftershocks that will spread from the epicenter of Sunday's quake in the Indian Ocean off Sumatra along a line about 600 miles (960 kms) long.
"I don't think there's any chance of a major earthquake of (magnitude 9) but there will be continued strong aftershocks," he told Reuters from USGS headquarters in Golden, Colorado.
He said USGS seismologists were aware of two quakes of magnitude 6.0 that struck on Wednesday alone.
The largest aftershock at 7.5 magnitude occurred, he said, about 3.5 hours after Sunday's main quake, the world's most powerful in 40 years that set off tsunamis that barreled across the Indian Ocean before striking coastal areas in south and Southeast Asia.
Deaths in the tsunami disaster could top 100,000 when figures for India's Bay of Bengal islands are known, a senior international Red Cross official said.
Sunday's quake beneath the Indian Ocean seabed was caused when the India plate dipped under the Burma plate, with the epicenter about 155 miles (250 km) off the Indonesian island of Sumatra.
"The ocean there is a hot zone for earthquakes," he said, adding that aftershocks "could continue for weeks or months," but "another one of magnitude 9.0 is highly unlikely."
As of Wednesday, he said, no USGS seismologists were planning to go to Asia because the quake occurred under water, making it difficult to study. Still, engineers will want to study the earthquake's damage to buildings wherever possible.
"For us at USGS, this is not the first earthquake in this (undersea) area. Quakes of (magnitude) 7 occur often," he said.
"But this was the largest and it generated a tsunami. There isn't much known about tsunamis, there's no history of them in the Indian Ocean, and so it's more of an opportunity for scientists who study tsunamis."
An international team of Japanese and US tsunami scientists will be going to the region to conduct field work that will provide additional data about the earthquake and advance understanding about earthquakes and tsunamis, said Dr. Harold Mofjeld, a senior scientist with the US National Ocean and Atmospheric Administration.
"The tsunami field data provides important additional information about the quake that can't be obtained by seismographic records," he said. "With this data and using computer models, it's possible to back calculate the tsunami source."
The team has to move quickly. "A problem with this study is that the scientific evidence of tsunamis tend to disappear rapidly as cleanup and humanitarian operations go forward," he said.
Story by Philip Barbara
REUTERS NEWS SERVICE
