Late on April 14, 2016, an M6.5 earthquake struck Kumamoto and Oita Prefectures in southern Japan. Many people—including earthquake experts—expected it to be followed by aftershocks diminishing in size. Powerful aftershocks did indeed follow, but on April 16 the region was rocked by an M7.0 quake—even bigger than the first major temblor in the series.
The Japan Meteorological Agency (JMA) uses a seismic intensity scale of its own devising to measure the intensity of earthquakes, employing data from seismographs installed in thousands of low-rise buildings. The JMA scale is analogous to the Mercalli intensity scale, and assigns levels 0 through 7 to earthquakes (since 1995, levels 5 and 6 have been sub-divided to provide two additional levels). On only three occasions prior to Kumamoto (in 1995, 2004, and 2011) had earthquakes been recorded at the maximum seismic intensity of 7: two of the quakes in the Kumamoto series were recorded at this level within 48 hours.
Impact and Losses
The Kumamoto earthquakes caused considerable damage to infrastructure. According to Japan's Fire and Disaster Management Agency, 8,193 residential buildings were completely destroyed, 25,328 were categorized as partly destroyed (approximately 20–70% of gross floor area or 20–50% of their main components damaged), and 122,923 were partly damaged (lighter repairs than partly destroyed structures). A total of 243 public buildings and 1,672 non-residential buildings were also damaged.
The Japan Times reports that the removal of rubble and building debris has barely begun in some of the worst affected areas, such as Mashiki and the village of Minamiaso (about 8 and 11 miles east of Kumamoto, respectively). Transportation in the region is still affected as remedial work on damaged infrastructure is just starting; the main road from Kumamoto to the Aso region and the Kyushu Railway Co.'s Hohi Line remain blocked by landslides. Of the 183,882 people evacuated from their homes, 7,007 are still waiting to return, according to the Emergency Response Headquarters for the region. The number of evacuees has been halved in Mashiki town and reduced to one-quarter in Kumamoto city. Most of the homeless are in temporary accommodations, but some are sleeping in their cars. Of the 3,910 temporary homes being built, 3,048 have been completed.
The General Insurance Association of Japan (GIA) has reported that residential claims had reached almost USD 3.5 billion as of July 31, and Japan's Cabinet Office announced recently that economic losses were expected to total USD 22–42 billion. Download AIR’s issue brief Modeling Supply Chain Disruptions and Contingent Business Interruption Losses to better understand how to rapidly assess the financial impacts of potential disruptions.
Learning from Disaster
Japan has stringent and well-enforced seismic building codes that are updated regularly. As a result of these, a recently built structure should resist the JMA seismic intensity 7 without collapsing. The law, however, regulates building strength on the assumption that major shake occurs just once, not multiple times. Some people were injured or killed when additional damage occurred in the second major temblor of the Kumamoto earthquakes, which is an issue that will need to be addressed in future updates.
Japanese infrastructure has been made steadily more resilient in the aftermath of major, damaging earthquakes. Because so many people were killed in the fires that followed the Great Kanto Earthquake of 1923, cities were rebuilt with nonflammable materials. The majority of casualties in the 1995 Hyogo-ken-Nanbu earthquake (also known as the Kobe earthquake) were caused by the collapse of buildings, resulting in the promotion of significantly enhanced seismic strengthening of buildings. The massive destruction and loss of life that followed the tsunami in 2011 spurred the Japanese government into constructing nearly 400 km of sea walls in the Tohoku region before extending the program to a further 35,000 km of coastline. The Kumamoto quakes will no doubt lead to further enhancements to Japan's resilience.
The better systems, organizations, communities, and individuals are prepared for catastrophes such as earthquakes, the easier their recovery afterwards will be. Earthquake insurance is available to provide protection for Japanese households, but it is offered as an optional addition to fire insurance policies and typically covers only 30–50% of the sum insured by those policies. Take-up rates vary from prefecture to prefecture and while they have increased in the wake of major earthquakes, the GIA's figures for 2014 indicate that overall penetration is still below 30%. Because the consequences can be so disastrous for the ill-prepared when powerful earthquakes strike, the GIA and non-life insurance companies are working to further close this protection gap.
A Slide Show of Images from AIR’s Kumamoto Damage Survey