20 Avril 2016
April 16, 2016 at 14:45 JST
The severe earthquake that rocked the southern prefecture of Kumamoto on April 14 caused major damage and scared a lot of people.
Numerous homes collapsed due to the violent shaking. In cities and towns, pedestrians were transfixed as they tried to get to grips with this latest natural disaster.
The quake reminded some people of the Great East Japan Earthquake that struck five years ago, while others were concerned about the safety of Kyushu Electric Power Co.’s Sendai nuclear power plant in neighboring Kagoshima Prefecture. The plant's No. 1 and No. 2 reactors are the only ones currently in operation in Japan.
The magnitude-6.5 earthquake in Kyushu had a maximum intensity of 7 on the Japanese seismic scale in Mashiki, a town of 35,000 or so souls near the epicenter.
In Kumamoto itself, tiles cascaded from the roof of the main tower of 400-year-old Kumamoto Castle and several ancient stone walls there crumpled. A 100-meter section of the 242-meter “Nagabei” (long wall), a designated important cultural property, collapsed.
It was the first earthquake of such intensity to strike since the 2011 temblor in northeastern Japan that generated devastating tsunami and the Fukushima nuclear calamity. Many Japanese, with the exception of residents affected by the big earthquake five years ago, seem to be becoming less conscious of the risk of a major seismic event occurring.
We need to remain keenly aware that nowhere in the Japanese archipelago is spared the danger of earthquakes. Any earthquake, even one in a remote area, should be taken as a warning not to take safety for granted.
We urge everybody to pay serious attention to this latest event and carefully prepare for major quakes in the future, while helping where they can in providing disaster relief to affected areas and supporting recovery efforts.
RESCUE OPERATIONS 1ST PRIORITY
The death toll from the Kumamoto earthquake as of late April 15 stood at nine. Most of the victims are believed to have been trapped under collapsed buildings.
Self-Defense Forces personnel and members of Emergency Fire Response teams rushed to the quake-hit areas to begin rescue operations. First and foremost, all-out efforts must be made to search for and rescue survivors while considering the risk of a secondary disaster.
One notable fact is that the quake has been followed by unusually frequent and strong aftershocks.
The Japan Meteorological Agency warned that aftershocks measuring up to lower 6 on the Japanese seismic scale could occur in the next week or so.
Quakes of this intensity can cause weak wooden buildings to collapse and trigger massive landslides.
For the time being, local residents should avoid acting alone and stay away from damaged buildings or steep slopes.
More than 40,000 people took temporary shelter following the quake and many are still staying in community centers, schools and other makeshift facilities. Some survivors laid cardboard sheets on the ground to sit on.
It is still chilly in the morning and at night. Rain could add to the misery of survivors. Proper attention should be paid to the health of those in the affected areas.
VIOLENT QUAKES AND ACTIVE FAULTS
This is the fourth time Japan has been hit by a quake registering 7 on the seismic scale since the meteorological agency assigned that number to the maximum intensity of quakes in 1949.
The previous three are the Great Hanshin Earthquake, which flattened Kobe in January 1995 and had a magnitude of 7.3, the magnitude-6.8 Niigata Prefecture Chuetsu Earthquake in October 2004 and the Great East Japan Earthquake in March 2011, which had a magnitude of 9.0.
An earthquake’s energy doubles when its magnitude increases by 0.2 and becomes 1,000 times more powerful when the figure rises by 2.
Among the four severest quakes since 1949, only the 2011 temblor was a so-called ocean-trench earthquake, one caused by the shift of tectonic plates. The 2011 quake released enormous energy, some 360 times larger than the force of the Hanshin quake.
The other three were linked to active faults, or fractures within the Earth’s crust.
This type of earthquake releases less energy than ocean-trench quakes, with only limited areas shaken violently. Because the focus of such quakes is relatively close to the surface, however, areas right above the area hit tend to suffer severe damage.
The focus of the April 14 quake is close to the Futagawa fault belt and the Hinagu fault belt, which have been designated by the government’s Earthquake Research Committee as “major fault belts.”
The committee had predicted that a movement of part of these fault systems could cause an earthquake with a magnitude of between 6.8 and 7.5. If the entire system moves, the panel warned, a gigantic quake with a magnitude of between 7.5 and 8.2 could occur.
The committee had also said the probability of a major quake linked to these fault belts occurring within 30 years is relatively high.
The Kumamoto earthquake was smaller in scale than predicted. But the fact is that it produced shaking of a maximum intensity level on the seismic scale and caused loss of life even though the amount of energy it released was about one-16th of the force of the Hanshin quake.
The Japanese archipelago is crisscrossed with active faults. Some seismologists have argued that the Great East Japan Earthquake has ushered in a new era of increased and intensified seismic activity in Japan. Other experts say there are many active faults still to be discovered.
Even residents of areas without known active faults, let alone people living near recognized faults, should be adequately prepared for major quakes.
PREPARATION KEY TO SURVIVAL
Kyushu has been regarded as less conscious of the risk of big quakes than it should be.
Six months after the March 2011 earthquake, the education board of Mashiki invited a seismologist to deliver a lecture for the town's residents. The board tried to make local residents aware of the possibility of an earthquake with a magnitude of up to 8 occurring directly below their town and understand that enhancing the quake resistance of their homes is the most effective way to prepare for such events.
But only 70 percent of the houses in the town have been made quake-resistant, a lower ratio than the average for the entire prefecture.
Last year, the Tokyo metropolitan government distributed a booklet on dealing with a disaster to all 6.7 million or so households in the capital.
The booklet contains a broad range of information useful for efforts to become better prepared for disasters, such as a safety checklist for homes and advice for responding to quakes, like “Don’t rush down to the first floor if you are in an old building.” The booklet also offers tips for post-disaster life, such as a list of goods that should be reserved for emergencies including plastic wrap, which proved very useful in past disasters, and an illustration of how to make diapers with plastic grocery bags.
The booklet has been well received because of its useful and specific content.
The difficulty of rescue and relief operations following a powerful quake, say one measuring 7 on the seismic scale, for instance, is far greater if wider areas are affected.
The fact we all should keep in mind is this: The effectiveness of responses to quakes, especially big ones, depends, to a great extent, on how well local residents and households are prepared in ordinary times.