Most people were unprepared when the 2004 tsunami hit South Asia. Tsunamis weren’t as common in the Indian Ocean as in the Pacific, and there wasn’t a warning system in place.

Tsunamis have long devastated coastal areas and continue to be a threat in many parts of the world. Two of the most devastating tsunamis have occurred in the last two decades. Here are five of the worst tsunamis in history.

Worst Tsunamis in History

1. Indian Ocean Earthquake and Tsunami

December 26, 2004

Death toll: 227,899 people in 13 countries

On the morning of the tsunami, Sonali Deraniyagala was vacationing with her family on the Sri Lankan coast. She saw threatening tidal waves crash against the beach from her hotel room.

Her family fled and were picked up by a driver in an SUV. They were hit by the water moments later. Only Deraniyagala survived. She lost her husband, two sons, parents and best friend. 

The 2004 tsunami was the deadliest on record. It was caused by a 9.1 magnitude earthquake that occurred 18 miles below the ocean floor between the Burma and Indian Plates. The force caused an 800-mile-long rupture and a tsunami that spread in every direction.

The coast of Indonesia was one of the first areas hit with waves larger than 150 feet. The last tsunami slammed Africa’s coast hours later with 30-foot waves.

The force of the massive waves leveled buildings and, in some places, caused flooding as far as three miles inland. More than one million people were displaced, and the loss from the devastation was estimated at $13 billion. 

 2. Lisbon Earthquake and Tsunami

November 1, 1755

Death toll: Between 60,000 and 100,000 people.

People traveled from the Portuguese countryside to Lisbon for All Saints’ Day. By mid-morning, crowds gathered in churches, and the streets were livelier than usual.

But trouble was brewing in the Atlantic Ocean. Shifting near the southwest Iberian margin led to an 8.5 magnitude earthquake that was felt as far away as Germany. The buildings in Lisbon shook, and survivors described hearing a “horrible subterranean noise.” The city rocked from tremors for the next hour.

Many buildings were reduced to rubble, and survivors were sorting out the chaos when the tsunami hit. The death toll for the city was estimated to be around 30,000 people. Some scholars have argued the estimate was too low because bodies were removed from the city without being counted.

The tsunami produced waves between 19 and 50 feet that crashed into the Portuguese, Spanish and Moroccan coastlines, killing as many as 10,000 people in those areas. Damages were estimated to be as high as 48 percent of the Portuguese GDP. 

Read More: Here’s How Earthquakes Cause Tsunamis

 3. Eruption of the Krakatau Volcano and Tsunami

August 27, 1883

Death toll: 36,000

For months, sailors reported seeing activity from the Krakatau volcano, located on an Indonesian island between Sumatra and Java. The volcano finally erupted in late August in a series of early-morning explosions.

Each time the volcano exploded, hot gas and volcanic matter (called pyroclastic flow) burst into the ocean. The force from these pyroclastic flows formed tsunamis that slammed into nearby islands. For hours, coastal villages endured multiple 100-foot tsunamis. On Java, the 2,700-person town of Merak was completely decimated. Two people survived; the rest drowned.

Survivors of the tsunamis recalled seeing massive walls of water speeding toward the shore. By the time the waves receded, more than 300 coastal towns, and their inhabitants, had been washed away.

 4. Arica Earthquake and Tsunami

August 13, 1868

Death toll: 25,000

On a Thursday afternoon, people living near the borders of Peru and Chile felt foreshocks. They knew an earthquake was coming, and many were safely outside when an 8.5 magnitude earthquake struck around 4:30 p.m.

People near the sea watched as the water rose and then receded, leaving more than a mile of seabed exposed. Then, a tsunami more than 50 feet tall crashed onto the shore. And the waves kept coming. The second wave was more than 90 feet tall, and what little survived the earthquake, and the first wave was battered again.

The port town of Arica was destroyed, and one historian described survivors as lost in the aftermath, surrounded by suffering. Other coastal towns in Peru and Chile were also wiped away. Inland towns were also impacted, including those in Bolivia.

Besides the loss of life and the devastation of complete towns, the tsunami also wrecked many ships docked at the coastal port towns. Two U.S. Navy ships were in the Arica port when the tsunami hit. One carried $2 million worth of supplies, and both the ship and cargo were lost in the wave.

5. Tōhoku Earthquake and Tsunami

March 11, 2011

Death toll: 15,550 people

After an afternoon earthquake rocked Japan, people feared a tsunami would follow. At Okawa Elementary School in Ishinomaki City, students and faculty assembled in the courtyard. Some wondered if they should seek higher ground. Others worried about a potential landslide.

After 40 minutes, the faculty and students departed. The tsunami hit while they evacuated; 74 students and 10 teachers died. 

The disaster started under the ocean floor with a collision between the Pacific and North American plates that led to a 9.1 magnitude earthquake. Almost all of Japan felt the rumbles of the earthquake. And soon, 1,200 miles of Japan’s coastline felt the impact of a 130-foot tsunami.

In the coastal town of Ōkuma, the Fukushima Daiichi Nuclear Power Plant lost power. Emergency generators were flooded, and the plant’s three reactors cooled and released radiation. The town was quickly evacuated, and the incident was considered the worst nuclear disaster in decades.

In addition to the people evacuated from Ōkuma, more than 130,000 people were displaced by the tsunami, and the total economic loss was estimated to be $309 billion.

Read More: The Disasters You Might Not Think About