OPINION: Japan needs post-Kumamoto quake overhaul after factory damage, gas blast

Ten years ago, Kumamoto Prefecture was struck by two powerful earthquakes that measured maximum level 7 on Japan's seismic intensity scale, caused by the movement of the northern edges of the Hinagu and Futagawa fault zones. The most recent magnitude 7.1 quake on July 28 was also rated level 7 and appears to have originated from a different section of the Hinagu fault than the 2016 event.

Seismologists believe that not all of the fault has ruptured, meaning more disaster preparedness is necessary. Despite the high level of shaking, damage to buildings appeared relatively limited, likely due to many weaker structures collapsing or being retrofitted after the 2016 quakes. Stronger bridges were damaged or had to be closed, highlighting the need to review earthquake resistance measures for critical infrastructure like expressways.

The 1995 Kobe earthquake demonstrated the importance of strengthening bridge piers and wiring girders to prevent falls. The Nankai Trough megaquake poses a significant threat, and Japan should consider building in greater safety margins for routes like the Shin-Tomei Expressway. Many factories built since Japan's high-growth era stand on soft, potentially unstable ground, and may also be aging.

The central government should order a comprehensive inspection to ensure adequate seismic measures are in place. An explosion at the Aeon Mall Kumamoto mall appears to have been caused by a liquefied petroleum gas leak after the quake. The cause of the explosion and the effectiveness of earthquake countermeasures need to be investigated quickly.

Hospitals, including Kumamotominami Hospital in Uki, suffered major damage, and the burden of moving patients during disasters can worsen their condition. While the shaking continues, people should avoid sheltering at home with tilted structures or fallen walls and continue taking protective steps such as doing light exercises and stretching.