The unusually high number of aftershocks following Japan's strongest ever earthquake last Friday has caused concern among geophysicists that it may actually be a chain of separate quakes.
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Michio Hashizume, a Japanese geology expert working with Chulalongkorn University's Faculty of Science, said his contemporaries in Japan are wondering if the string of tremors felt around the county since Friday's 9.0-magnitude are actually aftershocks.
"We are questioning if they are really aftershocks, because in theory they should happen close to the epicentre, but this time, [some of] the [following] earthquakes have happened far from the epicentre," Mr Hashizume said.
"We are thinking the 9.0 earthquake may have triggered a chain of earthquakes. If so, we expect more earthquakes, possibly as strong as magnitude 7, within the next three days."
The geologists are concerned about the possibility of another big earthquake soon, which could create another tsunami, he said.