New 2 part series studying the causes and effects of volcanic activity - from the science behind eruptions to the social, economic and environmental impacts.
Runtime: 45 minutes
Living with Volcanoes - Cascade Volcanoes - Netflix
This article is for the volcanic arc. For the namesake mountain range see Cascade Range. The 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 700 miles (1,100 km). The arc has 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. Some of the major cities along the length of the arc include Portland, Seattle, and Vancouver, and the population in the region exceeds 10 million. All could be potentially affected by volcanic activity and great subduction-zone earthquakes along the arc. Because the population of the Pacific Northwest is rapidly increasing, the Cascade volcanoes are some of the most dangerous, due to their eruptive history and potential for future eruptions, and because they are underlain by weak, hydrothermally altered volcanic rocks that are susceptible to failure. Consequently, Mount Rainier is one of the Decade Volcanoes identified by the International Association of Volcanology and Chemistry of the Earth's Interior (IAVCEI) as being worthy of particular study, due to the danger it poses to Seattle and Tacoma. Many large, long-runout landslides originating on Cascade volcanoes have engulfed valleys tens of kilometers from their sources, and some of the areas affected now support large populations. The Cascade Volcanoes are part of the Pacific Ring of Fire, the ring of volcanoes and associated mountains around the Pacific Ocean. The Cascade Volcanoes have erupted several times in recorded history. Two most recent were Lassen Peak in 1914 to 1921 and a major eruption of Mount St. Helens in 1980. It is also the site of Canada's most recent major eruption about 2,350 years ago at the Mount Meager massif.
Living with Volcanoes - Major catastrophic eruptions - Netflix
1980 Eruption of Mount St. Helens
The 1980 eruption of Mount St. Helens was one of the most closely studied volcanic eruptions in the arc and one of the best studied ever. It was a Plinian style eruption with a VEI=5 and was the most significant to occur in the lower 48 U.S. states in recorded history. An earthquake at 8:32 a.m. on May 18, 1980, caused the entire weakened north face to slide away. An ash column rose high into the atmosphere and deposited ash in 11 U.S. states. The eruption killed 57 people and thousands of animals and caused more than a billion U.S. dollars in damage. 1914–17 Eruptions of Lassen Peak
On May 22, 1915, an explosive eruption at Lassen Peak devastated nearby areas and rained volcanic ash as far away as 200 miles (320 km) to the east. A huge column of volcanic ash and gas rose more than 30,000 feet (9,100 m) into the air and was visible from as far away as Eureka, California, 150 miles (240 km) to the west. A pyroclastic flow swept down the side of the volcano, devastating a 3-square-mile (7.8 km2) area. This explosion was the most powerful in a 1914–17 series of eruptions at Lassen Peak. 2350 BP Eruption of the Mount Meager massif
The Mount Meager massif produced the most recent major eruption in Canada, sending ash as far away as Alberta. The eruption was similar to the 1980 eruption of Mount St. Helens, sending an ash column approximately 20 km (12 mi) high into the stratosphere. This activity produced a diverse sequence of volcanic deposits, well exposed in the bluffs along the Lillooet River, which is defined as the Pebble Creek Formation. The eruption was episodic, occurring from a vent on the north-east side of Plinth Peak. An unusual, thick apron of welded vitrophyric breccia may represent the explosive collapse of an early lava dome, depositing ash several meters in thickness near the vent area. 7700 BP Eruption of Mount Mazama
The 7,700 BP eruption of Mount Mazama was a large catastrophic eruption in the U.S. state of Oregon. It began with a large eruption column with pumice and ash that erupted from a single vent. The eruption was so great that most of Mount Mazama collapsed to form a caldera and subsequent smaller eruptions occurred as water began to fill in the caldera to form Crater Lake. Volcanic ash from the eruption was carried across most of the Pacific Northwest as well as parts of southern Canada. 13100 BP Eruption of Glacier Peak About 13,000 years ago, Glacier Peak generated an unusually strong sequence of eruptions depositing volcanic ash as far away as Wyoming.
Living with Volcanoes - References - Netflix