Tseax Cone volcanTseax Cone (also called Tseax River Cone or the Aiyansh volcano) is a young cinder cone in the Northern Cordilleran Volcanic Province in British Columbia, Canada. It is the site of one of Canda's most recent eruptions, which was a major lava flow around the years 1750 or 1775. Tseax Cone's activity is present in legends and stories of the Nisga'a People.
Gas emissions from the volcano and major lava flows are the most significant hazards from Tseax Cone.
Introduction:Tseax Cone is related to the Nass Ranges and the Northern Cordilleran Volcanic Province, located east of Crater Creek at the outlet of Melita Lake, southeast of Gitlakdamix and 60 km north of Terrace, British Columbia, Canada.
The volcano is located in a valley above and east of the Tseax River, about 20 km (12 mi) south of the river's junction with the larger Nass River. It is one of the most accessible volcanic centers in British Columbia.
The Tseax Cone was the site of some of the youngest volcanic eruptions in Canada and has been active at least 2 times in the past few 100 years. It measures 290 m in diameter at its base and rests on the remnants of an earlier and somewhat larger, dissected, 460 m diameter cone. The volcano typically erupted fluid basalt lavas, producing fissure eruptions, strombolian activity and sometimes lava lakes inside its crater.
18th century eruption
A major effusive eruption occurred around the years 1750 or 1775. Basalt lava flows traveled into the Tseax River, damming it and forming Lava Lake. The flow subsequently traveled 11 km north to the Nass River, where it filled the flat valley floor for an additional 10 km, making the entire lava flow approximately 22.5 km long.
The Nass River valley contains abundant tree casts and lava tubes.
Native legends of the Nisga'a people tell of a prolonged period of disruption by the volcano, including the destruction of two Nisga'a villages. Several Nisga'a people dug pits for shelter, but approximately 2,000 Nisga'a people died due to volcanic gases and poisonous smoke (most likely carbon dioxide). The Nisga'a story of the destruction is Canada's worst known geophysical disaster.
The lava beds, which reach 12 m (39 ft) above the road in some places, are the burial ground of these people. It is the only eruption in Canada for which legends of First Nations people have been verified.
It has recently been suggested that the Tseax eruption was triggered by the Cascadia earthquake of 26 January 1700. This was the most powerful earthquake during the last 1000 years in the Pacific Northwest.
Sources: wikipedia, GVP
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