Kumamoto 7.1 earthquake: Hinaku fault rupture spans 30km, experts warn of future quakes

A powerful magnitude 7.1 earthquake struck Japan's Kumamoto Prefecture on April 28, with the shaking reaching the highest level of 7 on the Japan Seismic Intensity Scale. The earthquake, which occurred at a depth of approximately 16 kilometers, has resulted in at least 10 confirmed fatalities and widespread damage.

According to the Japan government's Earthquake Investigation Committee, the tremor was caused by the movement of a segment of the Hinaku fault zone, extending about 30 kilometers. This fault zone, which stretches approximately 81 kilometers, is divided into three sections. The committee believes that the recent earthquake involved a portion of the "Takano-Shirafuchi section" and the northeastern part of the "Hinaku section."

Experts are cautioning that remaining unruptured segments within the Hinaku fault zone pose a future risk. They indicate that these areas could rupture and trigger subsequent earthquakes, possibly with even greater intensity than the current event. The committee's chairman, Kazunari Obar, noted that the entire 81-kilometer fault could potentially generate an earthquake between magnitude 7.7 and 8.0 if it were to rupture simultaneously. Satellite data has also revealed significant crustal deformation around Kumamoto, with one observation point shifting approximately 87 centimeters northeastward.