The powerful earthquake that struck Osaka and neighboring prefectures during Monday’s morning rush hour, leaving five people dead and hundreds injured, once again exposed the vulnerability of large urban areas to major quakes. Even though the magnitude 6.1 quake — originating at a depth of 13 km under northern Osaka Prefecture and registering an intensity of up to lower 6 on the Japanese scale of 7 — was much less powerful than the 1995 Great Hanshin Earthquake and the 2016 Kumamoto quakes, city functions in many parts of the prefecture were extensively paralyzed, ranging from public transportation to water and gas supply.
It was the highest intensity earthquake to hit Osaka Prefecture since the seismic observation system was established in 1923. But the Meteorological Agency warns that an earthquake of this scale can happen anytime and anywhere in this country — even in areas that are normally not deemed to be quake-prone. The agency has called for vigilance against quakes of similar intensity hitting the area in the coming week. A similar-scale quake hitting Tokyo — which has a much greater concentration of population, buildings and houses — could cause far more damage. The Osaka quake should serve as yet another wake-up call for city administrators across Japan to review their preparedness for disasters.
The quake severely rocked many parts of northern Osaka just before 8 a.m. Monday, partially destroyed hundreds of people’s homes and forcing, as of Tuesday morning, roughly 1,700 people to take shelter, many likely overnight. Water and gas supplies remained suspended in some local municipalities and it will take another week or more for gas services to be restored in certain areas. The rupture of underground water pipes in Takatsuki due to the temblor is something that could happen in many other municipalities across the nation where the water infrastructure, built decades ago, is similarly old.
Disruptions to train services, including the Tokaido and Sanyo Shinkansen superexpress lines, inconvenienced hundreds of thousands of people throughout Monday, leading commuters to form long lines at train stations waiting for taxis. The earthquake also caused more than 200 elevators in high-rise buildings and condominiums in the quake-struck areas to cease operation, leaving many people temporarily stranded inside the elevators.
Two of the five victims in Monday’s quake were crushed by concrete walls that collapsed during the temblor, including a 9-year-old elementary schoolgirl in Takatsuki who was passing by her school’s swimming pool when the surrounding wall collapsed. Falling concrete walls have caused a number of fatalities in past earthquakes and safety standards have been updated, but many old walls that do not meet the improved standards reportedly remain on streets across the country.
In the 1978 quake that hit off Miyagi Prefecture, 18 of the 28 people killed were crushed by collapsing walls. The 1981 revision to the Building Standards Law tightened the quake resistance regulations for such walls. Many of the old walls built before the amendment to the law collapsed during the 1995 Great Hanshin Earthquake that devastated Kobe and its neighboring areas.
Anti-quake standards for buildings have been beefed up greatly in the wake of the 1995 Kobe quake and the 2012 Great East Japan Earthquake. The education ministry has promoted work to make public elementary and junior high school buildings more resistant to temblors of up to upper 6 on the Japanese scale, and work was completed on 98.8 percent of roughly 110,000 school buildings covered by the program as of April last year.
The quake-resistance of main school buildings and school gyms are regularly monitored. However, many old facilities such as walls surrounding school compounds have been left as is. The city of Takatsuki acknowledged that the swimming pool wall that collapsed and crushed the schoolgirl was much taller than permitted under current building standards and had no support structures. The national government says it will order municipalities across Japan and homeowners to check the safety of block walls surrounding school buildings and private houses.
Collapsed walls can hinder the passage of emergency vehicles and people’s evacuation in times of disasters. Some municipalities reportedly offer subsidies for owners of old walls to either destroy them or add support structures, but the application rate for such subsidies is said to be low. Experts say concrete walls are only one examples of vulnerable structures on streets that can become safety hazards when disasters strike. Those potential hazards should be scrutinized as municipalities explore measures to minimize the damage caused by future earthquakes.