Mount Erebus lava lake seen from space | Polarjournal
Image: NASA / Landsat 9 / OLI-2

Our planet’s most active and southernmost volcano did not escape the attention of Nasa observers when clouds freed it from its shackles at the end of November. Its lava lake is still molten.

The Landsat 9 Earth observation satellite captured a clear image of Mount Erebus on November 25. Its OLI-2 sensor reveals light signals from the volcano’s permanent lava lake – light radiation invisible to the human eye. These allow us to observe the eruptions of the Heard Island volcano, which was still erupting last October.

Here, towering above the clouds at 3,794 meters, Mount Erebus sits enthroned on Ross Island in the Ross Sea, and was first described in 1841 by the Erebus and Terror expedition led by James Clark Ross. The volcano’s current activity predates the explorers’ arrival, but the emergence of the lava lake follows it. The latter was first observed in 1972.

It is one of the few lava lakes left on the surface of the Earth’s crust, the other two being in Ethiopia and Congo. It sometimes throws up bombs of molten rock. Its magma is poor in water and rich in carbon dioxide, which facilitates its ascent to the surface. It converges on this choke point at the intersection of several faults, positioned on the youngest rift in West Antarctica: the Terror.

The volcano remains a mystery. Its low seismicity doesn’t offer many clues to scientists studying its internal anatomy. In 2014 and 2017, scientific expeditions therefore measured terrestrial electromagnetism at 129 sites, revealing the shape of the column of hot rock beneath the crater.

Graham Hill, physicist of terrestrial electromagnetism at the Czech Geophysical Institute, said after the expedition that “Erebus is one of the most accessible systems in the world, if not the most accessible”. Despite its geographical position on the periphery of major transport routes, the volcano is 35 kilometers from the McMurdo research station, and on the volcano’s slopes there are no obstacles, no forests, no property.

Camille Lin, PolarJournal

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