On September 29, 2009, a magnitude 8.1 earthquake shook the seafloor of the Pacific Ocean near the Samoan Islands. The earthquake caused a tsunami, whose 6-meter (20-foot) waves devastated the coastlines of Samoa, American Samoa, and Tonga. Nearly 200 people died.
The Samoan Islands are located in the southern Pacific Ocean, where two tectonic plates meet. Here, the massive Pacific plate subducts beneath the smaller Indo-Australian plate. This tectonic activity has made the region—stretching from New Zealand to an area just south of the Samoan Islands—one of the most prone to earthquakes and volcanoes.
Term Part of Speech Definition Encyclopedic Entry coastline Noun
outer boundary of a shore.
the sudden shaking of Earth's crust caused by the release of energy along fault lines or from volcanic activity.
very large or heavy.
vulnerable or tending to act in a certain way.
surface layer of the bottom of the ocean.
to pull downward or beneath something.
tectonic activity Noun
movement of tectonic plates resulting in geologic activity such as volcanic eruptions and earthquakes.
tectonic plate Noun
massive slab of solid rock made up of Earth's lithosphere (crust and upper mantle). Also called lithospheric plate.
ocean waves triggered by an earthquake, volcano, or other movement of the ocean floor.
an opening in the Earth's crust, through which lava, ash, and gases erupt, and also the cone built by eruptions.
Encyclopedic Entry: volcano wave Noun
moving swell on the surface of water.