Volcano Watch — Sub-Antarctic lava lake spied from space

Sources/Usage: Public Domain. View Media Details

Volcanoes on the Island of Hawai‘i have long played an important role in exploration of the moon, providing a training ground for astronauts who would bring back the first lunar samples. Today, as Mars beckons, astronauts still travel to Hawaii to practice for missions to our neighboring planet. 

But it isn't just other moons and planets that await exploration and provide geologists with the opportunity for new discoveries. Planet Earth still has many secrets to uncover and space-based technology is playing a critical role in understanding our planetary home. 

In 2008–2018, while Kīlauea hosted one of the most accessible and largest lava lakes for study, scientists sought to confirm another lava lake on the far side of the world. 

The target was Mount Michael, an active and exceedingly remote glacier-clad stratovolcano on Saunders Island in the South Sandwich Islands, a volcanic arc in the South Atlantic Ocean. The volcano is about 2550 km (1580 mi) roughly east of Ushuaia, Argentina, near the southern tip of South America. 

This island volcano is well-off the beaten path of mariners and aircraft and is often obscured by heavy clouds. A vapor plume emanating from the crater at its summit is commonly visible in satellite images and rare fly-overs by the British Antarctic Survey. This plume and a generally hot area coincident with its summit crater have long suggested high heat flow at the summit, but little is known about the full extent of the volcano's activity. 

Looking back in history at ship logs and other sources, ash clouds were reported in 1819, and a lava eruption may have occurred near the end of the 19th and beginning of the 20th centuries. Overall, due to the island's location, records of activity until the age of satellites are scant. 

In the 1990s, a coarse-resolution satellite thermal anomaly further indicated a source of high heat that could have been a temporary lava lake. But it was not conclusive, and the question remained: how active is this sub-Antarctic volcano?

As satellites have become more sophisticated and the pixel size smaller (resulting in higher image resolution), finding small areas of high heat flux—like a lava lake—has gotten easier. And so, using the power of satellites and the increasing number of observations, the question of a lava lake at Mount Michael appears to be resolved. 

British researchers looked at decades worth of imagery of this volcano from three different satellites: Landsat, Sentinel, and ASTER. They were able to confirm persistent temperatures greater than about 1000 degrees Celsius (1800 degrees Fahrenheit), consistent with a pool of lava at the surface within the summit crater. They further argue that the longevity of satellite thermal anomalies and plumes over the three decades of observation suggests a long-lived lava lake.

With this confirmation, it adds to the inventory of known persistent lava lakes on Earth: Ambrym in Vanuatu in the South Pacific, Erebus in Antarctica, Erta Ale in Ethiopia, Masaya in Nicaragua, and Nyiragongo in the Democratic Republic of Congo in Central Africa. 

The Mount Michael summit lava lake is about 110 meters (360 ft) wide covering an area of about 10,000 square meters (about 2.5 acres). Students of Kīlauea will recall that the lava lake within Halema‘uma‘u prior to its draining in May 2018 was about 300 m (nearly 1000 ft) across covering about 42,000 square meters (just over 10 acres). So, by Hawaii standards, the Mount Michael lava lake is just a small cousin. 

The discovery of a new lava lake a year after the loss of Kīlauea Volcano's summit lava lake reminds us of our dynamic planet and demonstrates the power of space-based observations of Earth, as well as the heavens.

For more information on Mount Michael, see the Smithsonian Institution's Global Volcanism Program webpage: https://volcano.si.edu/volcano.cfm?vn=390090.

Volcano Activity Update

Kīlauea Volcano is not erupting and its USGS Volcano Alert level remains at NORMAL. Reflecting this level, HVO is now issuing monthly updates for Kīlauea. For definitions of the alert levels, see https://volcanoes.usgs.gov/vhp/about_alerts.html.

Monitoring data for deformation have shown no significant changes in Kīlauea activity over the past week. Rates of seismicity across the volcano remain low. Sulfur dioxide emission rates are low at the summit and below detection limits at Pu‘u ‘Ō‘ō and the Lower East Rift Zone (LERZ). 

At or near the 2018 LERZ eruptive fissures, elevated ground temperatures and minor releases of gas (steam, tiny amounts of hydrogen sulfide, and carbon dioxide) persist. These are typical post-eruption conditions and are expected to be long-term, as they were after the 1955 LERZ eruption.

The water level at the bottom of Halema‘uma‘u continues to slowly rise. HVO is monitoring the pond closely, and under the current conditions, its presence in the crater has not increased the risk to public safety. 

Hazards remain at the lower ERZ and summit of Kīlauea. Residents and visitors near the 2018 fissures, lavaflows, and summit collapse area should heed Hawai‘i County Civil Defense and Hawai‘i Volcanoes National Park closures and warnings. The 2018 lava flows are primarily on private property, and people are asked to be respectful and to not enter or park on private property.

Mauna Loa is not erupting. Its USGS Volcano Alert level remains at ADVISORY. This alert level does not mean that an eruption is imminent or that progression to an eruption is certain. A similar increase in activity occurred between 2014 and 2018 and no eruption occurred. 

This past week, approximately 40 small-magnitude earthquakes (all less than M2.0) occurred beneath the summit and upper Southwest Rift Zone. Deformation measurements show continued summit inflation, suggestive of recharge of the volcano's shallow magma storage system. No significant changes in volcanic gas release on the Southwest Rift Zone were measured, and fumarole temperatures there and at the summit remain unchanged.

Mauna Loa updates are issued weekly. For more info on the status of the volcano, please go to: https://volcanoes.usgs.gov/volcanoes/mauna_loa/status.html

One earthquake with three or more felt reports occurred in Hawaii this past week: a magnitude 4.2 offshore quake 57 km (35 mi) southeast of Pāhala at 46 km (29 mi) depth on August 22 at 4:33 a.m. HST.

HVO continues to closely monitor both Kīlauea and Mauna Loa for any signs of increased activity. 

Please visit HVO's website (https://volcanoes.usgs.gov/hvo) for past Volcano Watch articles, Kīlauea and Mauna Loa updates, volcano photos, maps, recent earthquake info, and more. Email questions to askHVO@usgs.gov.

Volcano Watch (https://volcanoes.usgs.gov/observatories/hvo/hvo_volcano_watch.html) is a weekly article and activity update written by U.S. Geological Survey Hawaiian Volcano Observatory scientists and affiliates. No earthquakes were reported felt in the Hawaiian islands during the past week.