Repost: Guest Videos: Listening to Volcanoes At A Distance

Here’s a repost from 2018 about using infrasound to study volcanoes. It’s timely because new research using this technique has revealed that Alaska’s Bogoslof Volcano, most of which sits below the sea, recently produced bubbles bigger than a stadium! That’s not something you’d want to discover by sailing over it — much better to check it out at a distance.

And check out the bottom of the post for an October 25, 2019, update on Shishaldin Volcano from the AVO that wouldn’t be possible without infrasound!

Original post:

This is also helpful in remote areas like Alaska, where volcano monitoring is difficult but absolutely necessary because of heavy air traffic.

And, yes, if you sped up volcanic infrasound, it would sound just like an erupting volcano:

Here’s that October 25th AVO notice about Shishaldin; I’ve highlighted the word “infrasound” and also added a link so you can check out more AVO information about this beautiful but remote Alaskan volcano:

U.S. Geological Survey
Friday, October 25, 2019, 1:19 PM AKDT (Friday, October 25, 2019, 21:19 UTC)

54°45’19” N 163°58’16” W, Summit Elevation 9373 ft (2857 m)
Current Volcano Alert Level: WATCH
Current Aviation Color Code: ORANGE

Low-level eruptive activity continues at Shishaldin Volcano and now extends beyond the summit crater. Lava flows filled the summit crater over the past week and small flows overtopped the crater rim and flowed ~800 m (0.5 miles) down the northern slope by Thursday, October 24. Minor explosive activity with regular bursts of lava fountaining within the summit crater has been observed throughout the past week, depositing lava spatter around the summit in addition to a trace ash deposit that extends at least 8.5 km (5.3 miles) the southeast. A small steam plume has been visible over the past week as well. Melting of snow by lava and spatter has produced lahars that extend up to ~3 km (1.9 miles) down the northwest slope, with shorter lahars to the north and east. Low-level seismicity and infrasound signals continued to be observed on the local network throughout the past week.

Shishaldin is monitored by local seismic and infrasound sensors, satellite data, a web camera, a telemetered geodetic and tilt network, and distant infrasound and lightning networks. [Let’s do a separate post on volcanic lightning some time — Barb]

Shishaldin Volcano, located near the center of Unimak Island in the eastern Aleutian Islands, is a spectacular symmetric cone with a base diameter of approximately 16 km (10 mi). A 200-m-wide (660 ft) funnel-shaped summit crater typically emits a steam plume and occasional small amounts of ash. Shishaldin is one of the most active volcanoes in the Aleutian volcanic arc, with at least 54 episodes of unrest including over 24 confirmed eruptions since 1775. Most eruptions are relatively small, although the April-May 1999 event generated an ash column that reached 45,000 ft above sea level. . .

Volcanologists and Shishaldin in 2018. (Image: M. Loewen/AVO/USGS, public domain)

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