Earth’s surface may look solid—after all, we walk on it and construct buildings on it—but in fact, it is a constantly moving puzzle of interlocking pieces. These pieces, known as tectonic plates, are giant sections of Earth’s crust whose edges interact with one another by either colliding or moving apart. The plates of the outermost layer, the lithosphere, float on top of the malleable asthenosphere in Earth’s interior. The movement of these plates is called plate tectonics, and scientists have studied this field since the 1950s. While the movement of tectonic plates is usually slow—typically just a few centimeters per year—plate tectonics are linked to several kinds of natural disasters, namely earthquakes, volcanoes and tsunamis.

On the afternoon of March 11, 2011, a large earthquake struck off the northeastern coast of Japan. This deadly event was caused by a specific type of plate movement: subduction. Subduction occurs when one tectonic plate—the one that is older and denser—sinks or is pulled under another tectonic plate. This process does not, however, proceed smoothly; as tectonic plates shift and grind against one another, the friction can cause them to snag on each other. Once plates overcome this friction and move past each other, energy is released, leading to earthquakes. Near Japan, the Pacific Plate is subducting under the North American Plate. Although it may seem impossible, parts of Japan actually sit above a portion of the North American Plate.

In the 2011 Tohoku Earthquake—so named for the part of northeastern Japan that was struck hardest by the quake—a submerged section of the North American plate jolted upward in the Japan Trench. This undersea valley is located roughly 130 kilometers (81 miles) from the main island of Japan. The magnitude-9.0 earthquake produced by the upward movement of this plate, which was one of the most powerful quakes in recorded history, hoisted a wall of seawater.

That huge upwelling of water created a series of waves—also called a tsunami—that moved outward in all directions from the earthquake’s epicenter, both toward and away from Japan. The waves moved at speeds of up to around 800 kilometers (500 miles) per hour, roughly the speed of a jet airliner. When those waves rolled up on the eastern shore of Japan, the tallest measured more than 10 meters (33 feet) high. The waves that rushed toward the east eventually struck the U.S. state of Hawai‘i and then the western coast of the mainland United States, though with much less force. Intense ground shaking may have even changed the rotation rate of Earth, shortening the length of the day by about 1.8 microseconds.

The tsunami that hit Japan was far higher than the seawalls that had been built to protect the Japanese coastline from such inundations. The water rushed inland in a great flood, carrying with it ships, sweeping away cars and destroying buildings. Nearly 20,000 people died due to the earthquake and tsunami. Images captured on the day of the earthquake, as well as the days that followed, revealed a shattered landscape full of debris. The environmental impact of the 2011 earthquake and tsunami has been enormous; researchers studying soil samples have detected pollution from industrial chemicals and pesticides that leaked from the wreckage. That is not surprising given the amount of destruction caused by the disaster: oil refineries in flames, sewer and gas lines broken and chemical plants damaged.

The tsunami also crippled the Fukushima Daiichi Nuclear Power Plant near Sendai. Ocean waves caused flooding that cut off the plant’s electrical power, making it impossible to cool the plant’s nuclear reactors. As a consequence, three of the plant’s four reactors overheated, causing the uranium fuel rods to liquefy. The melted rods burned through the steel walls meant to contain them, releasing uranium and other radioactive materials into the air and sea. The airborne radioactive particles blanketed houses, crops and schools. Over 100,000 people were forced to evacuate from their homes.

Cleaning up radioactive contamination and dismantling the power station, a task that Japan is hoping to finish by 2051, could cost over 200 billion U.S. dollars. However, there have been setbacks. In 2025, the power company leading the cleanup operation had to delay a major project—removing damaged fuel debris from a reactor—until 2037. This came after a small test of how to remove fuel debris safely took longer and was more difficult than expected. Further tests are needed, because it is not clear what method would safely neutralize the radioactive debris. One method would be to submerge the debris in water, which would shield the radiation. Another method would be to fill the reactor with concrete or a similar material to solidify the debris and take it out. But the company still needs to further reduce radiation around the facility and build cleanup infrastructure before workers can safely remove the debris.

Adding to the complexity of these problems is that cleanup of the plant could have harmful effects. The United Nations Human Rights Council (UNHRC) is concerned that radioactive water released from the plant into the ocean could harm humans and the marine environment. The UNHRC is particularly concerned about the effects on children. Scientists think children are at greater risk for cancer from radiation since they are still growing and their cells divide more rapidly than adults.

Though Japan and other countries have tested new methods of permanently disposing of nuclear waste, no clear, safe solution has been found. Some countries have simply left waste in former power plants, while others continue to look for solutions. Finland, for example, has devised a method of enclosing waste in copper canisters and burying it in underground tunnels between 400 and 450 meters (1,312 and 1,476 feet) deep. But it is not clear what environmental impact these methods will have in the years to come. “The bitter reality is that there is no scientifically proven way of disposing of the existential problem of high- and intermediate-level waste. Some countries have built repositories, some plan them,” Paul Dorfman, founder of the Nuclear Consulting Group, told The Guardian. “But given the huge technical uncertainties, if disposal does go ahead and anything goes wrong underground in the next millennia, then future generations risk profound widespread pollution.”

Though some infrastructure and housing was rebuilt relatively quickly after the earthquake and tsunami, the social and emotional toll of the disasters on survivors continues. Studies of survivors of the earthquake and tsunami show they have higher levels of post-traumatic stress symptoms and depression. People who lost family members or pets in the tsunami have reported feeling guilty that they survived while their loved ones did not. There have been social and cultural challenges as well. In the areas surrounding the power plant, survivors report that they are at risk of losing their culture. Local traditions and festivals once held regularly have dwindled or disappeared because people have not returned to the area. Aware of this, the Japanese government and arts organizations increased efforts to keep traditions alive with programs that supported the arts. One example is the Reborn-Art Festival in the city of Ishinomaki, which celebrated the region’s food and music.

Since 2011, Japan has focused on reducing risks from earthquakes and tsunamis, both at home and abroad. For example, the government improved communication systems to alert people to earthquake and tsunami warnings and developed a drone unit to monitor the coast and warn people to leave when there is a tsunami warning. Japan also helped other countries create their own early warning systems. This support from well-resourced countries like Japan is important, because countries with fewer resources are at greater risk of death and destruction from natural disasters. This is in part because those countries have buildings with architecture that cannot withstand earthquakes and other natural disasters, and the government may not have enough money to equip each building. For example, during a 2015 earthquake in Nepal, a significant number of deaths came from collapsing buildings, but schools that had been retrofitted to combat damage from earthquakes all remained standing.

Marginalized people and communities tend to have fewer resources and face greater negative effects from natural disasters. In Nepal for example, the Dalits—a social class that faces discrimination—are forced to live in undesirable areas in structures that are vulnerable to earthquakes and other natural disasters. Because of discrimination from the government, they struggle to gain resources that would help them recover from a natural disaster, like the 2015 earthquake.

Governments, organizations and communities must take action to ensure all people and infrastructure can be well prepared for earthquakes and tsunamis. To prevent damage when a disaster occurs, scientists are working to predict when and where disasters caused by movements of tectonic plates will occur. By installing sensors capable of measuring ground movements, researchers can monitor earthquakes, even tiny ones, worldwide. This data allows scientists to assemble global maps of earthquakes to look for patterns in their locations. Researchers have also placed buoys in the ocean to detect tsunami waves traveling toward land. Detecting a tsunami before it floods a shoreline and issuing an alert can save many lives.