When the Ground Shakes

Living with earthquakes in Japan - understanding warnings, knowing what to do, and why preparedness becomes routine

This morning at 10:18, western Japan shook. A magnitude 6.2 earthquake struck eastern Shimane Prefecture, registering Strong 5 on the Japanese seismic intensity scale in Matsue, Yasugi, and parts of neighbouring Tottori. Japan uses the Shindo scale rather than the Richter or moment magnitude scales for reporting - it measures how strongly the ground shakes at a specific location, not total energy released, which makes it more useful for understanding local impact. The Sanyo Shinkansen halted between Hiroshima and Okayama. Power flickered. By 11:40, ten aftershocks had followed, including a magnitude 5.1 tremor.

No tsunami warning was issued. Prime Minister Takaichi asked residents to remain alert for further quakes. Nuclear plants reported no damage. Life, as it does here, continued.

If you live in Japan, earthquakes are routine.

The Warning System

Your phone will likely warn you before you feel anything. Japan's Earthquake Early Warning system detects initial seismic waves and broadcasts alerts seconds before the stronger shaking arrives. Every mobile phone sold here receives these alerts automatically - a piercing tone followed by urgent Japanese, then English.

Televisions switch to NHK's earthquake broadcast. The screen fills with a map, the epicentre marked, intensity readings updating in real-time. It's startling the first time. By the tenth, you learn to read it quickly: where, how strong, whether you need to act.

The warning gap - seconds between alert and shaking - depends on your distance from the epicentre. Sometimes it's enough to get under a table. Sometimes the alert arrives with the tremor itself. Either way, the system works. It saved lives during the 2011 Tohoku earthquake and continues to do so.

When the Ground Moves

Small earthquakes happen constantly. Most you'll barely notice - a slight sway, a rattle of windows, then stillness. Ever felt your first one? Anything below intensity 3 might go unremarked. Your Japanese colleagues won't look up from their screens.

Stronger quakes demand action. The guidance is straightforward:

Drop, Cover, Hold On. Get low, protect your head and neck, and hold onto something stable. Tables work. Doorframes are no longer recommended - that advice is outdated. If you're in bed, stay there and cover your head with a pillow.

Stay inside. The instinct to run outside is wrong. Falling objects - roof tiles, glass, air conditioning units - cause more injuries than the shaking itself. Wait until the shaking stops.

If you're outside, move away from buildings, power lines, and anything that might fall. Open areas are safer.

If you're driving, pull over gradually, avoiding bridges and overpasses. Stay in your car.

After strong shaking stops, check for gas leaks, turn off stove burners, and prepare for aftershocks. They will come.

Tsunami Risk

Coastal areas face an additional threat. The 2011 earthquake generated waves that reached 40 metres in some locations. The Pacific coast, particularly the Sanriku region, is most vulnerable, but the Sea of Japan coast sees tsunamis too.

Warning systems have improved since 2011. Sirens, loudspeakers, and smartphone alerts now give coastal residents minutes - sometimes longer - to reach high ground. Evacuation routes are marked throughout coastal towns. Learn yours.

Today's Shimane quake posed no tsunami threat - the shallow depth and location meant no significant water displacement. But this isn't always the case. If you feel shaking strong enough to make standing difficult, assume a tsunami is possible and move.

Being Prepared

Every household in Japan should have an emergency bag. Most do.

The essentials: Water (at least 3 litres per person), non-perishable food for three days, a torch, spare batteries, a battery-powered radio, a first-aid kit, copies of important documents, cash in small denominations, a portable phone charger.

Often overlooked: Medications you take regularly, glasses or contacts, sanitary supplies, something warm to wear, sturdy shoes you can grab quickly (broken glass is everywhere after strong quakes), a small amount of food and water for pets.

Store the bag somewhere accessible - near your entrance, not buried in a closet. Some people keep one at home and another at work. Workplaces are often far from where you live; you may not make it back that day.

Check your bag annually. Water and food expire. Batteries corrode.

Experiencing It First

If you want to know what a strong earthquake feels like before one happens, you can.

Disaster prevention centres across Japan offer earthquake simulations. The Ikebukuro Life Safety Learning Center in Tokyo has a room that replicates shaking up to intensity 7 - the highest on the Japanese scale. You'll sit at a table while the floor bucks and heaves. It's unsettling, but instructive. You learn how difficult it is to move, to think, to do anything except hold on.

Similar centres exist in Osaka (Abeno), Nagoya, Kobe, and most prefectural capitals. Sessions are free or inexpensive. Many offer English guidance. The simulations also cover fire extinguisher use, smoke-filled rooms, and first aid.

Worth an afternoon. The memory of how your body responds will return when you need it.

Historical Context

Japan experiences roughly 1,500 perceptible earthquakes annually. Most cause no damage. Some redefine the landscape.

The 1923 Great Kanto earthquake killed over 100,000 people in Tokyo and Yokohama. The 1995 Kobe earthquake collapsed elevated highways and killed 6,434. The 2011 Tohoku earthquake and tsunami claimed nearly 20,000 lives. The 2024 Noto Peninsula earthquake - just over a year ago now - killed over 400 and reminded everyone that the threat remains present.

Each disaster has prompted stricter building codes, better warning systems, improved evacuation procedures. The buildings constructed after 1981, when seismic standards were significantly strengthened, perform markedly better. Those built after the 2000 revisions, better still.

The Reality

Living with earthquakes becomes systematic. The subtle sway of a hanging light tells you whether to keep reading or move. You notice which shelves might topple. You keep shoes by the bed without thinking about why.

But Japan's preparedness is real. Buildings are engineered to flex rather than collapse. Infrastructure is designed with seismic loads in mind. Emergency services drill constantly. Communities practise evacuation. The systems work because they're tested - not annually, but routinely, by the earth itself.

Today's earthquake in Shimane caused no reported deaths. Services resumed within hours. The aftershocks will taper. By tomorrow, it will be a line in the earthquake record, one of the 1,500 this year, unremarkable except to those who felt the floor shift beneath them.

Be prepared. Know what to do. The infrastructure exists precisely so you can continue living.