On August 8, the Japanese Meteorological Agency issued its first-ever “megaquake alert” following a magnitude 7.1 earthquake in Miyazaki prefecture, Japan. The earthquake caused minor tsunamis and injured 16 people. The quake originated offshore near the Nankai Trough, raising concerns of a larger magnitude 8 or greater megaquake in the future, which could potentially have devastating consequences. The JMA stated that the risk of a megaquake remains high even after the alert period.
Seismologist Naoshi Hirata mentioned that the chance of a larger quake occurring in the area within the next week is relatively low but the risk of a magnitude 8 or 9 earthquake in the Nankai Trough within the next 30 years is significant. The recent earthquake does elevate the short-term risk, but this risk decreases with each passing day without another major quake.
Although Japan has a history of megaquakes, the recent alert does not signal a shift in long-term seismic activity trends. The alert was the second highest under the Nankai Trough Earthquake Extra Information protocol, which is activated by a magnitude 6.8 or greater quake. The Nankai Trough marks the interface of the Philippine and Eurasian plates, hosting large earthquakes every 100 to 150 years.
Back-to-back earthquakes are not uncommon, with a small chance of a larger quake following a smaller one. Japan implemented an earthquake early warning system in 2007 to provide advance notice of incoming seismic waves. In the event of a megaquake, the system aims to issue warnings before the arrival of more damaging waves, as seen during the 2011 Tohoku earthquake.
Looking beyond Japan, the Cascadia megathrust fault off the coast of North America poses a similar threat, with megaquakes occurring every few hundred years. The United States operates the ShakeAlert system to warn residents of potential earthquakes. Preparation is key for those living in earthquake-prone areas, with emergency supplies and knowledge of safety protocols essential for minimizing the impact of a quake.
In conclusion, the recent megaquake alert in Japan serves as a reminder of the constant seismic risk faced by many regions around the world. Through early warning systems, preparedness measures, and public awareness, communities can better equip themselves to handle the impact of future earthquakes. It is crucial to stay informed, have a plan in place, and be ready to act swiftly in the event of a seismic emergency.
