For planet Earth, the passage of five years and eight months represents nothing but a flash.

The earthquake that struck eastern Japan early on Nov. 22, believed to an aftershock of the Great East Japan Earthquake of March 11, 2011, served as a wake-up call for us humans whose memories are woefully short.

The magnitude-7.4 temblor hit a broad area from the Tohoku to Kanto regions, jolting people awake from their slumber.

The focus of the quake was off the coast of Fukushima Prefecture. The port of Sendai in Miyagi Prefecture recorded a 1.4-meter tsunami, the biggest in Japan since March 2011.

After the main shock of the March 2011 earthquake, temblors of magnitude 7 and above occurred six times over that year in areas where aftershocks were expected. Between 2012 and 2014, two quakes of the same scale struck. With the latest jolt, the total number of aftershocks of that scale is now 10.

This proves that seismic activity has not abated in the region. We should be prepared for more magnitude 7-class quakes in the days ahead.

This time, the tsunami pattern differed from the prediction of the Japan Meteorological Agency.

Initially, the agency issued a tsunami advisory for Miyagi Prefecture. But after a higher-than-expected tsunami was observed at Sendai, the advisory was upgraded to a tsunami warning.

The tsunami was bigger at Sendai than at the Fukushima Prefecture port of Onahama, which was closer to the focus of the quake. The meteorological agency says it does not know exactly why this happened.

Even if an earthquake is of a moderate scale, it can trigger a shift in the fault if its focus is shallow, and consequently cause a bigger tsunami than anticipated.

We must always bear in mind that no disaster prediction can be 100-percent accurate, and act accordingly to save our lives.

This time, many people became alarmed when they learned of the temporary failure of the cooling water pump for the spent nuclear fuel pool at the Fukushima No. 2 nuclear power plant operated by Tokyo Electric Power Co.

But this in itself was no cause for alarm. It happened when the pump’s automatic shutdown mechanism kicked in upon sensing a change in the water level caused by the earthquake.

In the immediate aftermath of the March 2011 disaster, however, the shutdown of the cooling water pump at the Fukushima No. 1 nuclear power plant presented a serious threat to the spent nuclear fuel. A possible massive release of radioactive substances was feared.

We are concerned that this particular lesson from the 2011 disaster may have already been forgotten.

The Nuclear Regulation Authority is currently calling on electric power companies to adopt the “dry storage” system for cooling spent nuclear fuel by natural convection airflow, rather than with water.

But since adopting this system opens the way for long-term fuel storage on power plant premises, utilities are reluctant to go ahead, fearing it will invite resistance from local communities and also a review of the nuclear fuel cycle system itself.

However, we believe the utilities must put safety first and comply swiftly with the NRA’s call.

The latest temblor also turned the public’s eyes again to the danger of the radiation-contaminated water that keeps collecting in the tanks at the Fukushima No. 1 plant.

We must all learn humbly from each disaster. It is up to all of society--individuals and corporations alike--to keep planning viable countermeasures steadily and surely.

Ultimately, that is the only way to prepare for the next disaster, which may strike even today.

--The Asahi Shimbun, Nov. 23