Seismic Activity Persists along Kumamoto’s Hinagu Fault Zone

Tokyo, Aug. 3 (Jiji Press)–Seismic activity along the Hinagu fault zone remains elevated a week after a powerful earthquake hit Kumamoto Prefecture, southwestern Japan, leading the Meteorological Agency to warn of possible strong shaking and tsunami waves. Five quakes measuring lower 5 on the Japanese seismic intensity scale had occurred along the fault zone as of Saturday, following Tuesday’s temblor with a magnitude of 7.1, which registered an intensity of 7, the highest level on the scale. The agency is urging residents to remain prepared for a possible temblor with an intensity of up to 7 and tsunami waves that could be unleashed in the event of an undersea quake. According to the government’s Earthquake Research Committee, Tuesday’s quake caused part of the Hinagu fault zone to shift along a stretch of about 30 kilometers, while subsequent quakes happened across an area spanning about 50 km. About 380 quakes with an intensity of 1, the minimum that can be felt, or higher had occurred by Monday afternoon. A quake with a magnitude of 5.8 that registered up to lower 5 on Wednesday occurred under the sea near the Yatsushiro Sea segment of the fault zone off the coast of the prefecture. The event suggested that seismic activity could extend into the segment. The Geospatial Information Authority said Tuesday’s quake caused right-lateral strike-slip crustal deformation along the fault zone, with the western side on the plains moving northeast and the eastern mountainous side moving southwest. The largest movement recorded at a constant observation point occurred at the Sencho site in the prefecture’s city of Yatsushiro, southwest of the epicenter. The ground shifted about 87 centimeters northeast and subsided about 32 centimeters. At the time of the 2016 Kumamoto quake disaster, the first major quake, which had a magnitude 6.5, occurred when the Takano-Shirahata segment of the Hinagu fault zone moved on April 14. The second, which had a magnitude 7.3, resulted from a movement along the Futagawa segment of the Futagawa fault zone two days later. “It’s impossible to know where and how intense the shaking will be,” Kazushige Obara, chair of the Earthquake Research Committee, said at a Wednesday press conference. “But people should remain aware that even stronger shaking is possible and prepare accordingly.” END [Copyright The Jiji Press, Ltd.]