United States Geological Survey It's been a busy week in the realm of volcanoes. Let's check out some highlights: Hawaii The coastline of the Big Island of Hawaii continues to change this week. The lava benches near the
Kamokuna ocean entry (part of Kilauea's episode 61g lava flows) have been collapsing for the better part of a few months, and those collapses look like they will be continuing. A crack has formed along the coastline near the ocean entry, and over the last few days it has continued to grow---complete with creaking and groaning at night as the block of lava moves. Most likely, this will become another piece of the island that will fall into the sea.
USGS geologists from the Hawaii Volcano Observatory took some infrared heat measurements of the cracked lava bench and found that it reaches over 220ºC (428ºF) only a few meters below the surface. The severed lava tubes continue to carry lava to the sea, creating some spectacular "hoses" of lava entering the ocean (see video above and below). It might seem like the lava is very similar to water, but it is both much more viscous (by a factor of 10,000 to 100,000!) and much hotter, likely erupting at temperatures around 1200ºC. This means that the lava can explode as it hits the ocean water and trapped steam in the magma tries to escape. These explosions are unpredictable and violent, so while these fountains of lava are impressive, they should be treated with caution---I've seen quite a few photos and videos of tourist boats coming perilously close to these ocean entries.
United States Geological SurveyTonga While searching for pumice rafts on satellite images in the area near Tonga, a coastal geomorphologist in New Zealand discovered an active submarine eruption on January 27, 2017. The volcano in question, the ever-so-wonderfully named "Submarine Volcano III," is only about 46 kilometers (29 miles) from the capital of Tonga, but poses no threat to the area at this point. The eruption likely started around January 23, 2017 (based on back-tracking satellite images) and has produced an area of discolored water in the seas to the northwest of Nuku’alofa. Brad Scott from GNS Science said that SubVol-III (as I'll call it) has been active a number of times over the last 50 years, with an impressive eruption in 1999 that produced a small, ephemeral island. SubVol-III is likely a composite volcano that lies under the surface of the Pacific Ocean. The summit of the volcano is likely only 10 to 20 meters below the surface, so the fact that this eruption has not produced explosive plumes (like we've been seeing at Alaska's Bogoslof) suggests that it is a fairly minor eruption.
Landsat 8 image of the eruption of Submarine Volcano III (discolored water to left) in Tonga, seen on January 27, 2017.NASA Earth Observatory The eruption itself could have gone unnoticed except for the vigilant eyes of geomorphologist
Murray Ford from the University of Auckland and the NASA/USGS Landsat 8 Earth-observing satellite. The NASA Earth Observatory posted images of the submarine plume (see above), showing that it stretches over an area over five kilometers (three miles) wide. This eruption from SubVol-III is the first noticed at the volcano since the 1999 eruption, but with its remote location (and being under the sea and all), other eruptions could have easily gone unnoticed. Submarine eruptions such as these are common in the southwestern Pacific.
Other volcano news:Etna in Italy continues to rumble after its first eruptions of 2017 started last week. Video taken today (February 2, 2017) shows strombolian explosions throwing lava bombs away from the new crater that has formed in the saddle between older vents on the Southeast Crater. Eruptions at Bogoslof in Alaska appear to have settled down some, although the current activity seems to rise and fall rapidly. The Alaska Volcano Observatory has lowered the alert status to Orange/Watch for the time being. Ash fall from Bogoslof was noticed on some nearby islands along the Aleutian chain, including in Unalaska. The island home of Bogoslof has doubled in size since the eruptions started in mid-December 2016.