Submarine earthquake

A submarine, undersea, or underwater earthquake is an earthquake that occurs underwater at the bottom of a body of water, especially an ocean. These earthquakes are the main reason why tsunamis happen. Scientists measure how strong these earthquakes are using tools like the moment magnitude scale and the Mercalli intensity scale.

The movement of Earth's plates, called plate tectonics, explains why submarine earthquakes occur. The Earth's outer layer, or lithosphere, is made of large pieces called plates that float on a layer of hot rock called magma in the asthenosphere. These plates slowly move and sometimes get stuck. When they finally break free, the sudden movement under the sea floor causes an earthquake. The point where this happens is called the epicenter.

Unlike earthquakes on land, the biggest danger from a submarine earthquake often comes from the waves it creates. These waves, known as tsunamis, can travel across the ocean and reach coastal cities, causing great damage and loss of life. Submarine earthquakes can also break submarine communications cables, which helps connect the Internet and international telephone network around the world. This is a big problem in places like Asia, where many cables cross areas known as the Pacific Ring of Fire.

Tectonic plate boundaries

The way tectonic plates move under the ocean floor can cause submarine earthquakes. These plates can push against each other in different ways, creating friction and shaking the ground below the water. Some of the biggest areas where these underwater earthquakes happen are near the Pacific Ring of Fire and the Great Sumatran fault.

When two plates push toward each other, the heavier plate slides under the lighter one, creating deep trenches like the Mariana Trench and the Puerto Rico Trench. When plates slide past each other, like along the San Andreas Fault, they can get stuck and then suddenly jump, causing earthquakes. When plates move apart, magma rises to fill the gap, sometimes forming new underwater volcanoes or causing earthquakes near places like the Mid-Atlantic Ridge.

List of major submarine earthquakes

Here is a list of some major submarine earthquakes that have happened since the 1600s. These powerful events under the ocean are often what cause tsunamis, big waves that can affect coastal areas. Each earthquake on this list shows how strong and important these underwater events can be.

Storm-caused earthquakes

A 2019 study found that large ocean storms can cause undersea earthquakes when they pass over certain areas of the ocean floor. These areas include Georges Bank near Cape Cod and the Grand Banks of Newfoundland. Similar effects have also been observed in the Pacific Northwest.