Do Japanese households have enough supplies to withstand a major earthquake?

In Japan, the risk of a major earthquake along the Nankai Trough or directly under Tokyo is increasing. Most households don’t have the necessary stockpiles to withstand such a large-scale event, since residents are unable to picture exactly what kind of challenges a major earthquake would bring.

This article considers the consequences of a major earthquake directly under Tokyo, and highlights what shortages should be anticipated in such an event.

Japan is an earthquake-prone country. In recent years, we have seen multiple major earthquakes, including the Great Hanshin-Awaji Earthquake, the Great East Japan Earthquake, the Kumamoto Earthquake, and 2024's Noto Peninsula Earthquake. More are anticipated in the future. Research estimates the probability of a magnitude 7 (M7)-class earthquake directly under the capital city within the next 30 years at 70%, and the probability of an M8–9-class earthquake along the Nankai Trough within the next 30 years at approximately 80%^*1.

Earthquakes cannot be accurately predicted or prevented, but proper precautions can substantially reduce the damage they cause. Fundamental for household preparedness is the stockpiling of daily necessities, such as food and drinking water (including stockpiles maintained under the “rolling stock” method^*2). Urban areas in particular, due to their high population density, risk having to accommodate more evacuees than their shelters are able to manage. Relief supplies may also take time to arrive, further highlighting the importance of stockpiling.

The national government and local authorities have specifically asked households to maintain a stockpile. For example, the Tokyo Metropolitan Government (TMG) requests its residents to stockpile food and daily necessities sufficient for at least three days, and even recommends stockpiling one week's worth in preparation for the need to shelter at home.^*3

Currently, however, households are not stockpiling enough. In January 2024, the Tokio Marine Research Institute conducted a survey of 2,004 people living in the 23 wards of Tokyo and the Minato Mirai area of Yokohama City in Kanagawa Prefecture, to ascertain the current level of stockpiling in urban areas with many high-rise condominiums. The survey confirmed that the state of household stockpiles is insufficient. If not rectified, when a major earthquake strikes, evacuation shelters risk rapidly running out of emergency supplies as they are flooded with victims.

Here are some of the main takeaways from the survey:

Figure 1 shows the results of a question on the state of food stockpiling by households. The percentage of households that have stockpiled the minimum amount of food necessary for three days, as stipulated by the government, is only about 50%. Over 30% of households have not stockpiled any food at all.

Figure 2 shows the places where people answered they would evacuate to in the event of a major earthquake. Partly because of insufficient stockpiles, the percentage of people who plan to evacuate to a shelter is approximately 45%. This significantly exceeds the evacuation shelter population coverage rate in Tokyo's 23 wards (the ratio of estimated shelter capacity to the total number of residents), which stands at 23%^*4.

Amid the bustle of daily life, it may be hard to think of a major earthquake as an issue that affects us directly. I recommend shifting our perspectives and trying to imagine the damage such an event would cause us. What type of situation would we be in if a major earthquake occurred?

A damage prediction is detailed in a report entitled "Damage Estimates in Tokyo due to an Earthquake Directly Hitting Tokyo"^*5, which the TMG revised in May 2022.

Starting with essential lifelines, Figure 3 shows the predicted water supply outage rates in the highest damage scenarios. Recovery is estimated to take about 17 days. For other essential services, restoring electricity is estimated to take around four days, and gas up to six weeks. Furthermore, due to limitations in the damage estimation methodology, the report states a possibility that damage can be significantly higher, leading to an even longer recovery period.

In addition to lifelines, the report goes into detail about potential damage to infrastructure and the state of evacuees and supplies. Due to the stockpiling issue, as well as the suspension of lifelines and people’s tendency to buy in bulk, the following supply shortages are expected, further demonstrating that stockpiling after an earthquake hits is already too late.

Consequently, supplies at evacuation shelters are also expected to quickly run out.

Take a moment to imagine this scenario. If a major earthquake were to hit Tokyo causing the shortages listed above and you didn’t have enough household stockpiles in place, what would you do? You might be horrified. The faces of your family members might come to mind. No one wants to see their loved ones suffer.

A massive earthquake will definitely strike at some point. I encourage to see this risk as affecting you personally, and raise the priority of stockpiling in your mind.

I explained the importance of household stockpiles in preparation for major earthquakes we expect to see in the near future, such as those directly below Tokyo or along the Nankai Trough. I hope that you will recognize the need to take measures to keep your family safe, and take practical steps so that when the time comes, you can act calmly and without panic.