Cascade VolcanoesThe Cascade Volcanoes (also known as the Cascade Volcanic Arc or the Cascade Arc) are a number of volcanoes in a volcanic arc in western North America, extending from southwestern British Columbia through Washington and Oregon to Northern California, a distance of well over . The arc formed due to subduction along the Cascadia subduction zone. Although taking its name from the Cascade Range, this term is a geologic grouping rather than a geographic one, and the Cascade Volcanoes extend north into the Coast Mountains, past the Fraser River which is the northward limit of the Cascade Range proper.
SeattleSeattle (siˈætəl ) is a seaport city on the West Coast of the United States. It is the seat of King County, Washington. With a 2022 population of 749,256 it is the most populous city in both the state of Washington and the Pacific Northwest region of North America. The Seattle metropolitan area's population is 4.02 million, making it the 15th-largest in the United States. Its growth rate of 21.1% between 2010 and 2020 made it one of the country's fastest-growing large cities.
Megathrust earthquakeMegathrust earthquakes occur at convergent plate boundaries, where one tectonic plate is forced underneath another. The earthquakes are caused by slip along the thrust fault that forms the contact between the two plates. These interplate earthquakes are the planet's most powerful, with moment magnitudes (Mw) that can exceed 9.0. Since 1900, all earthquakes of magnitude 9.0 or greater have been megathrust earthquakes.
Duwamish peopleThe Duwamish (dxwdəwʔabš, dxwdəwʔɑbʃ, ) are a Lushootseed-speaking Native American people in western Washington, and the indigenous people of metropolitan Seattle, where they have been living since the end of the last glacial period (c. 8000 BCE, 10,000 years ago). The modern Duwamish descend from at least two separate groups: the dxwdəwʔabš, or Duwamish, and the x̌ačuʔabš, or Hachuamish, being the largest. Traditionally, the Duwuamish spoke a subdialect of the southern dialect of Lushootseed, which is a Salishan dialect continuum that is spoken throughout the Puget Sound region of Washington.
Ring of FireThe Ring of Fire (also known as the Pacific Ring of Fire, the Rim of Fire, the Girdle of Fire or the Circum-Pacific belt) is a region around much of the rim of the Pacific Ocean where many volcanic eruptions and earthquakes occur. The Ring of Fire is a horseshoe-shaped belt about long and up to about wide. The Ring of Fire includes the Pacific coasts of South America, North America, Russia's Kamchatka Peninsula, and some islands in the western Pacific Ocean.
Episodic tremor and slipEpisodic tremor and slip (ETS) is a seismological phenomenon observed in some subduction zones that is characterized by non-earthquake seismic rumbling, or tremor, and slow slip along the plate interface. Slow slip events are distinguished from earthquakes by their propagation speed and focus. In slow slip events, there is an apparent reversal of crustal motion, although the fault motion remains consistent with the direction of subduction. ETS events themselves are imperceptible to human beings and do not cause damage.
Washington (state)Washington (ˈwɑːʃɪŋtən), officially the State of Washington, is a state in the Pacific Northwest region of the Western United States. Named for George Washington—the first U.S. president—the state was formed from the western part of the Washington Territory, which was ceded by the British Empire in 1846, by the Oregon Treaty in the settlement of the Oregon boundary dispute. The state is bordered on the west by the Pacific Ocean, Oregon to the south, Idaho to the east, and the Canadian province of British Columbia to the north.
Vancouver IslandVancouver Island is an island in the northeastern Pacific Ocean and part of the Canadian province of British Columbia. The island is in length, in width at its widest point, and in total area, while are of land. The island is the largest by area and the most populous along the west coasts of the Americas. The southern part of Vancouver Island and some of the nearby Gulf Islands are the only parts of British Columbia or Western Canada to lie south of the 49th parallel.
Puget SoundPuget Sound (ˈpjuːdʒɪt ) is a sound of the Pacific Northwest, an inlet of the Pacific Ocean, and part of the Salish Sea. It is located along the northwestern coast of the U.S. state of Washington. It is a complex estuarine system of interconnected marine waterways and basins, with one major and two minor connections to the open Pacific Ocean via the Strait of Juan de Fuca—Admiralty Inlet being the major connection and Deception Pass and Swinomish Channel being the minor.
Oceanic trenchOceanic trenches are prominent, long, narrow topographic depressions of the ocean floor. They are typically wide and below the level of the surrounding oceanic floor, but can be thousands of kilometers in length. There are about of oceanic trenches worldwide, mostly around the Pacific Ocean, but also in the eastern Indian Ocean and a few other locations. The greatest ocean depth measured is in the Challenger Deep of the Mariana Trench, at a depth of below sea level. Oceanic trenches are a feature of the Earth's distinctive plate tectonics.
