Chain reaction activated separate fault zone in 2nd huge quake

"TOKYO — Seismic experts believe a magnitude 7.3 quake that rocked southwestern Japan in the early hours of Saturday occurred on a separate fault zone from a massive temblor that struck barely a day earlier, and was triggered by a chain reaction involving a series of tremors.

The 1:25 a.m. earthquake, with the same intensity as the 1995 Great Hanshin Earthquake, was about 16 times as large as a magnitude 6.5 temblor that hit Kumamoto Prefecture Thursday night, the Japan Meteorological Agency said, describing the latest jolt as the main quake and the initial one as a foreshock.

The governmental Earthquake Research Committee concluded Friday that the magnitude 6.5 quake happened on the 81-kilometer-long Hinagu fault zone running along the central part of the island of Kyushu.

Shinji Toda, professor of earthquake geology at Tohoku University, said the 64-kilometer-long Futagawa fault zone located north of the Hinagu zone could have moved to cause the fresh quake."

[link to www.japantoday.com]