SAKIGAKE管理人 On April 14, 2016, a magnitude 6.5 earthquake struck Mashiki Town in Kumamoto Prefecture, registering the highest seismic intensity of 7.
Just 28 hours later, a second and even larger earthquake of magnitude 7.3 hit the same region, again reaching seismic intensity 7.
This unprecedented event—two seismic intensity 7 earthquakes in rapid succession—occurred in an area previously thought to have an extremely low probability of large-scale seismic activity. It significantly impacted disaster awareness in Japan.
Now, nine years later, there are still many lessons to learn and perspectives we must not forget.
As professionals in the field of disaster risk reduction, we reflect once again on the essential truths the Kumamoto Earthquake revealed.
■ Two Seismic Intensity 7 Quakes: Were Our Assumptions Realistic?
In the history of Japan’s seismic observation, the Kumamoto Earthquake was the first case in which two earthquakes of seismic intensity 7 occurred in the same area within such a short period.
Initially, the April 14 quake was considered the mainshock, but the even larger quake two days later required a new interpretation—what we thought was the mainshock turned out to be a foreshock. This shattered the assumption that “once it shakes, it’s over,” highlighting the potential for multiple large shocks with unpredictable timing.
Another key point: the government’s long-term earthquake risk assessment estimated the probability of a magnitude 6.8 or greater earthquake in this region within 30 years at just 0–0.9%.
Many residents admitted that, based on this, disaster preparedness had often been deprioritized.
But the Kumamoto Earthquake reminded us that low probability does not mean zero risk. Disaster risk must be evaluated not only by numbers, but by potential impact.
■ The Hidden Toll: The Severity of Disaster-Related Deaths
Another major characteristic of the Kumamoto Earthquake was the large number of disaster-related deaths, rather than deaths directly caused by the earthquake itself.
Due to prolonged evacuation, the stress of temporary housing, declining health, and isolation, more than 200 people died later, accounting for over 80% of all fatalities.
These are not the visible images of destruction, like building collapse or tsunamis. Rather, they are the quieter, long-term effects that often go overlooked.
In aging communities especially, the adequacy of evacuation environments and long-term health support systems can literally mean the difference between life and death. This must be a priority in future disaster planning.
■ What We Need Now: Preparedness with Imagination
The Kumamoto Earthquake fundamentally challenged our conventional thinking about disasters.
Two major shocks, widespread disaster-related deaths, and a low-probability region struck hard—all of these revealed how fragile our assumptions were.
Preparedness is not just about following data or probability; it’s about imagining the “what if.” That imaginative capacity—an ability to envision the unexpected—is what can save lives.
As time passes, memories of disasters fade. But continuing to apply the lessons is our responsibility as disaster risk professionals.
April 14, 2025—nine years since the Kumamoto Earthquake.
Let us take this day to reflect, and to revisit what true preparedness really means.
Image Source: kirokuma!