A drive through the Cascade Mountain Range across Oregon and Washington exposes you to some of the most magnificent volcanoes in North America. Mount Hood, Mount Rainier, Mount St. Helens, Baker, Jefferson, Adams, and the list goes on. The whole Cascade Range is volcanically active, but we only need to look to the Mount St. Helens eruption of 1980 to see the destructive force of these giants. Interestingly, there may be another volcano in the region that is more active than Mount St. Helens and goes unnoticed by most of us.
If you stand on Cannon Beach, Oregon, with your toes in the water and look to the west, then you will be looking towards a real hotspot of volcanic activity. Approximately 300 miles due west of Cannon Beach and 4,600 feet under the surface of the ocean lies the Axial Seamount. This volcano was first detected in the 1970s and has erupted three times since then: 1998, 2011 and 2015. The Axial Seamount is the most active volcanic site in the North Pacific Ocean.
Hotspots and plate boundaries
The Axial Seamount sits on a boundary between two tectonic plates, and it is also located over the Cobb Hotspot. “Hotspot” refers to an area where the magma from the lower mantle upwells. The magma extrudes through the earth’s crust and onto the surface, or the ocean bottom in this case. The seamount straddles the southeastward moving Juan de Fuca Plate and the northwestward moving Pacific Plate.
The Axial Seamount is the most recent volcano to form over the Cobb Hotspot. It is also part of the Cobb-Eickelberg seamount chain. This chain is a string of volcanic centers. So, the volcanoes extend 745 miles from the Axial Seamount location to the Aleutian Trench off the coast of Alaska.
Axial Seamount’s summit height above base level is 3,600 feet. The base of the feature covers an area of about 300 square miles. The summit contains an unusual rectangular caldera that measures 2 miles by 5 miles and is about 165 feet deep. A relatively recent technical paper published by the American Geophysical Union discusses the geologic history of the summit Axial Seamount (Clague, D.A et al., 2013).
The proximity of this Seamount to the Oregon coast has made it easier to study than many other submarine volcanoes. Soon after the discovery of the Seamount, the National Oceanic and Atmospheric Administration (NOAA) obtained access to the USA Navy’s SOSUS system (a network of submerged hydrophones) to monitor earthquake activity emanating from the Axial Seamount. NOAA was able to verify 8,247 small earthquake events that occurred over eleven days in association with the 1998 eruption.
So, next time you are standing on Cannon Beach put your toes in the water and try to “feel the shake.”
Washington: home to dangerous volcanoes (Source: ArcheanWeb) – https://archeanweb.com/2019/12/12/washington-home-to-dangerous-volcano/ Also:
Disaster on White island (Source: ArcheanWeb) – https://archeanweb.com/2019/12/10/disaster-on-white-island-dangerous-volcano/ Also:
Volcanic tsunamis (Source: ArcheanWeb) – https://archeanweb.com/2020/01/13/volcanic-tsunamis/ Also:
Clague, D. A. et al. (2013), Geologic history of the summit of Axial Seamount, Juan de Fuca Ridge, Geochemistry Geophysics Geosystems, 14, 4403–4443. doi:10.1002/ggge.20240 https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/ggge.20240 Also:
Smithsonian Institution: https://volcano.si.edu/volcano.cfm?vn=331021 Also:
Live Video from Axial Seamount: https://oceanobservatories.org/streaming-underwater-video/ Also: