Natural Disasters in Japan

A Risky Country

Unfortunately, natural disasters in Japan are not an uncommon occurrence. Out of 172 countries listed in the 2016 World Risk Report, Japan ranked 155 and was considered to have a “very high chance of disasters”. The report looks at a countries exposure and vulnerabilities to natural disasters such as earthquakes, volcanoes, typhoons, etc. When looking further into the kinds of natural disasters that can occur in Japan as well as their frequency, it’s no wonder Japan is ranked so poorly.

Types of Natural Disasters in Japan

Japan is prone to pretty much every type of natural disaster. Earthquakes, tsunamis and typhoons are the big ones, but flooding and landslides are also not uncommon. Even erupting volcanoes aren’t out of the question. Let’s look more in depth at each of the natural disasters and see what they are and how often they effect Japan.

Earthquakes

Japan is located in the Ring of Fire, which is an area known for its high number of earthquakes and volcanic eruptions. These natural disasters are a consequence of plate tectonics and their collisions. Japan is located at the intersection of three plates: the Filipino Plate, the North American Plate, and the Eurasian Plate, with the Pacific Plate nearby. This combination makes for a lot of seismic activity.

While Japan experiences over 1500 earthquakes per year, most of those will be hard to even notice. Some will cause a brief shaking sensation and up to a dozen or so each year will be rated 6.0+ on the Richter scale. For reference, Michigan Tech’s seismology site describes the impact of different magnitudes of earthquakes and says that 6.1 – 6.9 “May cause a lot of damage in very populated areas.”

Japan has its own earthquake scale called Shindo, which ranges from 0 – 7. However, most earthquake are quantified based off of the widely used Richter magnitude scale. While Shindo is meant to measure the intensity of shaking at different locations on the surface, the Richter scale measures the energy released at the epicenter of the earthquake. This means there is only one number reading for the Richter scale and multiple readings for the Shindo scale depending on the location of the quakes.

The Richter scale is a logarithmic scale ranging between 0 – 9. This means that every whole number step up is 10 times more powerful. So a magnitude 5.0 earthquake releases 10 times the energy of a 4.0, while a 6.0 releases 100 times that of a 4.0.

In 2011, Japan suffered a massive 9.1 magnitude earthquake that rocked the Tohoku region in Northern Japan. The epicenter occurred about 40 miles off the coast with the initial quake lasting 6 minutes. For context, the 2011 Tohoku earthquake was the fourth largest earthquake ever recorded and subsequently the costliest monetarily at 235 billion dollars worth of property damage. Fortunately, it was not proportionally deadly. However, there were still around 15,000 deaths from the earthquake, aftershocks and tsunami that followed.

While 15,000 deaths is a lot, it’s not the largest in the world or even Japanese history. The deadliest Japanese earthquake was the Great Kanto earthquake of 1923, which killed around 105,000 people. This quake measured in at 7.9 magnitude, but due to the location of the quake, as well as the antiquated buildings compared to the more earthquake resistant ones in the 2011 quake, the death toll was much higher.

Japan is well aware of its propensity for earthquakes and takes many precautions. All new buildings, as well as structures like the Tokyo Skytree, are built to be earthquake resistant. Even the Shikansen (bullet trains) are designed to use seismic sensors to stop the trains in the event of an earthquake. In the 2011 earthquake all 27 Shinkansen stopped before the earthquake hit and as a result there were no deaths or injuries on-board. Also, smart phones are designed to send out emergency messages to all Japanese phones that alert people before earthquakes and tsunamis strike. The alerts may only give people a few seconds to react, but it means that they can try to get to cover and possibly save their lives.

Tsunamis

Tsunamis are formed from large shifts in ocean water. This normally means they are consequences of other natural disasters like earthquakes, volcanic eruptions or landslides. Tsunamis are not the same as tidal waves and aren’t just one super tall wave, but rather several super long waves. Each wave can be almost 60 miles long and spread out up to an hour apart from each other.

A tsunami doesn’t always start close to the eventual collision point on land. Reaching speeds of 500 mph and traveling across the ocean in just a day, they move extremely fast and far with little loss of energy. That also means that scientist can predict when and where they will strike and provide evacuation warnings.

While traveling through the ocean, most ships and their sailors won’t even notice them as they just glide above the surface of the waves only a few feet tall. However, once they’re near shore, all of the long waves slow down and compress as they rapidly rise in height, up to 100 feet! The name tsunami (津波) means “harbor wave” as the wave would suddenly appear out of nowhere once it got close to the harbor.

The dangers from a tsunami aren’t just for people near the shore, as they can push water inland up to a mile. In a populated areas, they’ll push over trees, cars, buildings and anything else in their way. This is especially dangerous for low lying areas. Once finished, the water will then recede, dragging all of the debris it collected out into the ocean.

Fortunately, dangerous tsunamis only occur, globally, about twice per year and are not as common as other natural disasters. However, when a tsunami does hit a populated area it can be incredibly destructive, which is exactly what happened during the 2011 Tohoku earthquake. The earthquake caused a tsunami which flooded over 217 square miles of Japan, destroying towns and killing thousands.

While many towns had protections against tsunamis in the form of seawalls and channels to divert water, the 2011 tsunami overwhelmed many of these defenses which took people by surprise. Because of this, the Japanese government changed its disaster prevention policy to have the seawalls raised to protect against the highest possible tsunamis that could conceivably happen. They’ve also worked to teach their citizens proper evacuation procedures should another tsunami be detected.

This devastating tsunami was also the reason Japan has turned away from nuclear power as it caused the meltdown at the Fukushimi Daichii nuclear plant. The plant was on emergency power due to the earthquake and workers were attempting to shutdown the reactor, which needed to go through a cooling process first. However, the backup generators were not properly protected from tsunamis and when the seawall was breached, it caused the generators to fail. This caused the meltdown, several large explosions and some leakage of radioactive material.

Typhoons

Typhoons are the northwest Pacific equivalent of a hurricane. Typhoons are most likely to threaten Japan between July and October with around 25 typhoons forming and about 10 that actually “hit” Japan. Typhoons bring heavy rainfall and strong winds between 74 mph to over 120 mph!  

In 2019 Typhoon Hagibis became a Category 5 Super Typhoon with 10-minute sustained winds of 195 km/h (120 mph) and 1-minute sustained winds of 295 km/h (185 mph). The storm caused almost 100 fatalities and about 15 billion dollars worth of damage. Which makes it the costliest, not adjusted for inflation, Pacific typhoon on record and the deadliest in Japan since 1979. The deadliest part of Hagibis was the rainfall that caused massive flooding and resulted in over 80 of the total deaths.

Due to climate change, the intensity of typhoons are expected to increase in terms of winds, rainfall and storm surge. However, the number per year may drop. While less typhoons would be nice, having them be more intense is overall worse and the Japanese government is aware of this problem. After Hagibis, some are questioning if the government is doing enough to prevent flooding. There have been reductions since 1998 in the budgets from water control projects, which include dams and levees.

Volcanoes

According to Volcano Discovery, Japan has 270 volcanoes and over 100 of them are active, which is about 10% of all of the active volcanoes in the world! Because of this fact, Japan has a deep connection to volcanoes. Many of them are hiked, like Mt. Fuji, and many of them provide water to onsen (hot springs). While Japan has learned to live with volcanoes, they still unexpectedly erupt from time to time.

In the last 30 years, Japan has had over 20 different volcanoes erupt. One of which, Sakura-jima, has had several eruptions since 2009 and is still erupting periodically as of the time of this writing in December, 2020.

In 2014, Mt. Ontake unexpectedly erupted and killed at least 63 people. These volcanoes are monitored and advisories are issued when necessary. The advisories detail whether to avoid climbing the area due to toxic smog or to evacuate due to an eruption. However, it is still possible for an active volcano to unexpectedly erupt and catch people off guard like Ontake. For the most part, volcanoes, while numerous, aren’t the deadliest natural disasters in Japan.

Flooding and Mudslides

Other natural disasters that Japan can experience are things like flooding and mudslides/landslides which are often caused by other natural disasters. Japan is very mountainous, so mudslides and landslides can and do occur. Simultaneously, Japan also has many low-lying plains that are below sea level, which flood easily.

Retaining walls are common to help prevent landslides and the building codes are strict. People often tear down and rebuild houses and doing so requires upgrading to the latest earthquake and retaining wall codes. As for floods, dams and levees as well as monitoring and maintenance of rivers help to keep things in check. Tokyo in particular has an amazing underground tunnel system that diverts water into massive underground shafts, which then go into a huge tunnel that channels the water out and away into a large river.

Is It Safe to Live in Japan?

While Japan is one of the most natural disaster-prone areas in the world, it is also a first world country with a large economy that has a lot of experience and historical data to deal with these disasters. The country continually monitors and upgrades its defenses against these natural disasters.

Only around 150 people are killed in a natural disaster in Japan every year, at least on average. Which is not too far off the United States, which had 180 natural disaster deaths in 2019. The obvious outlier for Japan is 2011, which had 17,051 casualties because of the earthquake and tsunami. Even then, disasters with thousands of deaths historically happen once every 15 – 50 years. With this perspective, dying from natural disasters in Japan is highly unlikely and it’s reasonable to state that, yes, living in Japan is quite safe.