Japan has a long history of natural disasters. BOSAI explores how to overcome them and save lives with the power of science. This first program is about tsunami. First, we visit ruins in Miyagi Prefecture from the 2011 Great East Japan Earthquake, and learn how the psychological state of "normalcy bias" affects humans in a disaster. We also look at the characteristics of a tsunami, and new initiatives created with the aid of a supercomputer to help with evacuation drills and other countermeasures.

Japan's cities are often located in low-lying areas along rivers and are paved with concrete and asphalt, putting them at risk of flooding in the event of heavy rain. In recent years, significant damage has been caused by overflowing drains and backflow along drainage channels. In this program, we'll look at the unique mechanisms of urban flooding and explore ways to protect against disaster.

Typhoon Jebi, which struck Osaka Prefecture in 2018, is said to be the first typhoon to have hit a modern metropolis in Japan, and many buildings were damaged. According to experts, the destruction of those buildings could not be explained by the maximum instantaneous wind speed observed by the Japan Meteorological Agency. Urban structures may be to blame. Researchers believe that eddies of wind intensify around high buildings, causing sudden gusts of strong winds that exceed the observed values. In this episode, we will scientifically analyze the mechanism of sudden urban windstorms and explore ways to save lives.

In the 2011 Great East Japan Earthquake, high-rise buildings in Tokyo's Shinjuku district, some 400 kilometers away from the epicenter, continued to sway significantly for 13 minutes. This is thought to have occurred when the high-rise buildings experienced resonance from the earthquake's "long-period seismic motion." Furthermore, in the 2016 Kumamoto earthquakes, a type of motion called a "long-period pulse" was recorded for the first time in Japan, presenting a new challenge for earthquake countermeasures. In addition to examining these types of earthquake motion, we'll also look at the effects of earthquakes on buildings and explore ways to save lives.

Localized torrential rain is occurring with greater frequency in Japan. Flash floods from the heavy rain not only cause rivers to overflow but threaten homes and human life. This kind of weather has been difficult to predict, given the short timeframe between the formation of cumulonimbus clouds and the onset of rain. Yet a new type of radar called "phased-array radar" and a simulation using a Japanese supercomputer have been developed to forecast local downpours 10 minutes in advance. In this episode, we'll take a closer look at how the latest technology is being used to forecast localized torrential rain and protect lives.

An increase in heavy rainfall in recent years has made debris flows a frequent problem in Japan. We'll look at research underway to help with their early detection and explore ways to protect lives.In recent years, debris flows have become more frequent in Japan due to an increase in heavy rainfall. Given that about 70% of Japan's land area is covered by mountains and forests, they have become a significant issue. After large-scale debris flows struck parts of Hiroshima Prefecture in 2014 and 2018, scientists found that debris flows tend to start out small and then repeatedly recur, causing significant damage. Research is now underway to determine the locations where debris flows are likely to occur based on topographical and geological data, and install sensors that can detect the very first debris flow. Information from these sensors can then help residents evacuate as quickly as possible. In this program, we'll introduce the latest research to save lives from debris flows.

Mt. Fuji has been an object of faith for many Japanese. On the other hand, it has also caused numerous disasters with repeated eruptions. According to a simulation released by the Japanese government in March 2021, the next eruption could cause up to 10cm of volcanic ash to accumulate in Tokyo, about 100km away, within a few hours. Volcanic ash contains small jagged pieces of volcanic glass that can cause severe eye pain. Furthermore, volcanic ash can become electrically conductive when it absorbs rain, damaging power grids and triggering power outages. Moreover, it is expected to cripple the transport system, including automobiles, trains and airplanes, leading to significant damage in the urban areas. What can we do to prepare for the eruption of Mt. Fuji? Find out the things you can do in your daily life to protect yourself from volcanic disasters.

In Japan, the temperature is continuing to rise due to the effects of global warming and heatstroke cases are also on the rise. Heatstroke is a condition in which the body loses the ability to regulate its own temperature in a hot humid environment. It causes nausea, dizziness, delirium and could even lead to death. Professor Akimasa Hirata of Nagoya Institute of Technology developed a way to simulate the core body temperature using computer models of the human body. His research is helping to predict the risk of heatstroke. Furthermore, another research is underway that combines this technology with urban climate simulations. Discover ways to protect yourself from heatstroke through the latest research.

The 2018 torrential rains in western Japan killed 51 people in the Kurashiki City town of Mabi in Okayama Prefecture. Many of the victims drowned on the first floor of their home despite having a second story available. Why weren't they able to evacuate? A simulation of the flooding revealed that flood waters rose at a much faster rate than initially expected, highlighting the importance of early evacuation during heavy rain and flooding. Meanwhile, home builders have been developing completely new houses that prevent damage from flooding. In this program, we'll take a closer look at the threat of home flooding as well as some of the latest countermeasures.

Japan experiences an average of 23 tornadoes per year. They often cause serious damage when they strike in populated areas such as plains or along the sea. Tornadoes are also considered the most difficult type of weather phenomenon to predict, with few effective countermeasures available. Now, research is underway to capture the process of tornado formation using the latest radar, and to predict tornadoes using data from ground-based observation equipment. We'll take a closer look at the latest developments in tornado research and new efforts underway to protect lives.

In 1995, the Great Hanshin-Awaji Earthquake struck Japan's Hyogo Prefecture early in the morning. Immediately after the earthquake, multiple fires broke out at the same time. Those who could not escape the fires lost their lives, and a total of 6,434 people died in the disaster. According to one investigation, 2 out of 3 people noticed the fires but did not evacuate immediately. Why was this? Reasons included delayed evacuation, an inability to evacuate and evacuation confusion. Now, the latest research is helping us understand the unexpected difficulties in trying to escape from a city hit by post-earthquake fires. In this program, we'll explore what is necessary to save lives.

Avalanches occur suddenly, damaging houses and injuring people. Many of the avalanches that occurred in Yamanashi Prefecture in 2014 took place in locations where avalanches are uncommon. We now know that many of these were "slab avalanches," in which a slab of surface layer snow is dislodged. How and why did these slab avalanches occur? We'll look at the latest efforts to better understand the underlying mechanisms, and the steps being taken to save lives.

As a natural threat that can suddenly occur any time of the year at nearly any place around the world, lightning is formidable. Despite humanity's long history with lightning, there's still a surprising amount of misinformation about what to do during a thunderstorm. In this episode, leading Japanese experts on lightning will help us sort the facts from the myths, and show us new 3D imaging techniques that can trace the exact path taken by a lightning strike, which is expected to improve our predictions of when and where lightning will strike.

The Great East Japan Earthquake of 2011 caused unprecedented damage. Even areas 300 kilometers away from the epicenter suffered damages beyond what was predicted. A phenomenon called soil liquefaction occurred over a large area. Some 27,000 structures sank or tilted, causing massive damage. The city of Urayasu in Chiba Prefecture was particularly affected. Surveys later revealed that the city had all the criteria for liquefaction to occur. The key was groundwater depth. Find out the mechanism of liquefaction and the latest mitigation technology.

PM2.5 are extremely small particles. The WHO estimates that every year PM2.5 is responsible for 2.4 million premature deaths worldwide. What is the cause? According to a study conducted by Kyoto University, PM2.5, which enters the body through the respiratory organs, can damage cells and cause inflammation, worsening various diseases. It has also been linked to COVID-19. How do we deal with this invisible threat? In this program, we'll examine countermeasures and look at the latest research on prediction using space technology.

The Great East Japan Earthquake and the massive tsunami that followed caused unprecedented damage along the coast of the Tohoku region with waves over 16 meters high. Why was the initial tsunami warning inaccurate? Errors are thought to have occurred as a result of tremors that exceeded what scientists had anticipated. Professor Shunichi Koshimura of Tohoku University is developing a completely new tsunami prediction system after realizing the limits of the current system. The key is to make predictions based on data gathered by observing real-time movements of the earth's crust. This new system is to be applied to the mega earthquake projected to hit Japan in the near future. Find out the latest in tsunami prediction technology that will lead to saving human lives.

What is a human stampede? It is a disaster in which people are so crowded together that they push and squeeze against each other, making it hard to breathe. It can also cause a person to fall, triggering a domino effect that results in casualties. In the past, human stampedes have taken the lives of countless people. In Japan, there is a high risk of a mega-quake hitting directly beneath the Tokyo metropolitan area in the near future. If this occurs, up to 8 million people are expected to be stranded in the city, creating a high possibility of human stampedes. What can we do to prevent casualties? Find out about the latest research on crowd safety.

The Great East Japan Earthquake in 2011 and its resulting tsunami caused the accident at the Fukushima Daiichi Nuclear Power Plant. The worst nuclear accident in Japan's history suffered from a lack of information due to the inaccessibility of the reactor buildings. For this reason, "disaster response robots" were deployed to take pictures and measure radiation doses inside the buildings. In the aftermath of a major disaster like that as well as an earthquake or fire, robots can quickly enter dangerous sites that are inaccessible to humans, find people in need of rescue, and take detailed measurements to provide data about the site. In this episode, we'll look at the latest developments among Japan's "disaster response robots."

Mt. Ontake is located on the border of Nagano and Gifu prefectures. Standing 3,067 meters above sea level, it is a popular daytrip hiking spot for mountain enthusiasts. Mt. Ontake was crowded with climbers around noon during a September vacation season, when the sudden stream-driven "phreatic eruption" occurred. Many climbers panicked as they encountered this unexpected natural phenomenon. Why couldn't this eruption be predicted? According to experts, there are 3 main types of volcanic eruptions, and the warning signs of phreatic eruptions are the hardest to detect. Now researchers are making advances to detect the slightest signs of an eruption using observation satellites and chemical approaches. Find out the latest on the research of volcanic predictions.

Linear rainbands. Once they occur, the area is hit with heavy downpour for an extended period of time, resulting in flood damage. In Japan, this phenomenon has been drawing attention ever since it struck in 2014, bringing torrential rainfall to Hiroshima Prefecture. While various studies led by the Japan Meteorological Agency are underway, it is still difficult to make accurate forecasts of linear rainbands at this point. When and where do linear rainbands occur? The mechanisms are still not understood. Find out how researchers are taking on the challenge to predict linear rainbands by accurately observing the location and the amount of water vapor in the atmosphere and performing rapid calculations.

In November 2021, the surface of a road in Mikasa, Hokkaido Prefecture suddenly caved in. A car fell into the large hole that formed, seriously injuring its three passengers. No underground construction work had been going on in the surrounding area, and the accident occurred without warning. Road cave-ins and other types of sinkholes happen not only in Japan but also in cities all over the world. One of the major causes is deterioration from aging pipes underground. Experts warn that multiple factors combine to cause sinkholes. In this program, we'll look at how sinkholes form as well as their countermeasures using the latest technology.

In February 2022, an American space exploration company simultaneously launched 49 satellites. Yet not long after, 40 of those satellites fell out of orbit and burned up upon re-entry into the Earth's atmosphere. Similar accidents have occurred frequently in the past. The cause of such incidents is believed to be solar flares, huge explosions that occur on the sun's surface. Solar flares can also lead to other disasters that threaten our daily lives, such as major power outages, radio interference, and communication problems for airplanes and ships. Why do solar flares occur? We'll visit some researchers in Japan that are working hard to understand their mechanism and predict future occurrences.

More than 10 typhoons hit the Japanese archipelago in an average year. Their strong winds and heavy rains can cause flooding and landslides, even toppling buildings. To minimize such damage, Japan is working to further improve its predictions and monitoring of typhoon activity. But, accurately predicting a typhoon's changing strength is particularly challenging. To address this, researchers now fly a plane into the eye of a typhoon to measure the actual atmospheric conditions directly on-site. In this episode, we learn more about flying into these fierce typhoons.

When a typhoon or similar storm approaches, air pressure drops and the sea surface is sucked up. Strong winds also push seawater towards the shore. These factors combine to create a storm surge, a rise in the sea level that often results in coastal flooding. As an island nation, Japan is particularly vulnerable to storm surges. What will happen to the power of storm surges as climate change progresses? According to the latest research, the damage caused by storm surges is expected to become more severe, while the frequency of "once-in-50-year" storm surges may increase. We'll introduce some of latest measures to cope with this prospect.

In recent years, heavy snow has been falling frequently in Japan. While the overall amount of snowfall per winter has been decreasing year by year, the amount of snow that falls at one time is conversely increasing. What role does climate change play in this? It turns out that rising temperatures have led to more water vapor in the Sea of Japan, and interaction with a weather phenomenon called JPCZ has subsequently brought on heavy snow. We'll examine the mechanism behind this as well as the risks of snow disasters.