VOLCANO WATCH: The Other Side of The World

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If you were to drill a hole straight through Earth from Hawai’i, you would eventually reach Botswana in Southern Africa. Not far from there—in the Indian Ocean off the east coast of Madagascar—lies a little French island called La Réunion. And on the east side of this island is an active volcano named Piton de la Fournaise.

On the morning of Feb. 4, 2015, Piton de la Fournaise started to erupt.

Although more than 10,000 miles from Hawai’i, this eruption was of unusual importance for scientists studying Kīlauea. In fact, Piton de la Fournaise and Kīlauea, both of which are among the most active volcanoes in the world, are remarkably similar. They are known for erupting basaltic lava flows (but have produced explosive eruptions in the past) and for being capable of producing large landslides and tsunamis—and both are located within national parks on tropical ocean islands. Visiting La Réunion, you sometimes feel as if you have not left Hawai’i—although French is the language of choice and the cars are much smaller!

Because of these and other similarities—as well as some important differences—the USGS Hawaiian Volcano Observatory (HVO) and the Observatoire Volcanologique du Piton de la Fournaise (OVPF), located on La Réunion and responsible for monitoring its namesake volcano, have established an ongoing collaboration and exchange program. In November 2014, a scientist from OVPF spent two weeks at HVO learning about Hawaiian volcanism, and on Jan. 30, 2015, a scientist from HVO landed on La Réunion.

When that scientist arrived, Piton de la Fournaise had not erupted for more than six months. Although there were a few minor indications of unrest, there was nothing to suggest an imminent eruption. On Feb. 3, scientists climbed to the rim of the volcano to retrieve a broken thermal camera. All was quiet.


But early on the morning of Feb. 4, OVPF’s monitoring network detected an increase in the number of small earthquakes near the summit, and within a matter of hours, hundreds of earthquakes had been recorded. Authorities were alerted and the area near the volcano’s summit was closed to visitors. Scientists and staff gathered in OVPF’s crisis room to watch, in real-time, as monitoring data poured in from the volcano.

When it became clear that an eruption was imminent, a field crew rushed toward the summit. Weather conditions were poor and visibility was limited, and near the summit, the team nearly stumbled onto a recent (but already cool) lava flow. Continuing through thick fog and heavy fume, the team located the main eruptive site. From at least four locations, lava was being thrown into the air with the roar of a jet engine, and lava flows were moving down the summit cone and spreading into the surrounding caldera, which, fortunately, is uninhabited.

The eruption continued for a week and a half. During that time, OVPF scientists mapped and sampled active lava flows, estimated gas emission rates, interpreted geophysical data to better understand the source of the magma driving the eruption, and communicated findings to the press and public officials. In this sense, the response by OVPF to the eruption was very similar to how HVO responds to eruptions in Hawaiʻi.

One of the few significant differences between HVO and OVPF is that helicopter overflights are rare at Piton de la Fournaise due to frequently poor weather and high costs. Another is that Piton de la Fournaise eruptions last from days to a few weeks, whereas the current eruption of Kīlauea has been continuous for decades.


HVO and OVPF hope to learn much from each other’s work. The February 2015 eruption of Piton de la Fournaise marks an auspicious early phase in what we hope will be a long and productive collaboration between HVO and OVPF.

Kīlauea activity update

Kīlauea’s East Rift Zone lava flow fed breakouts across the leading 2.5 km (1.6 mi) of the flow. When mapped on Thursday, Feb. 19, the most distal activity on the flow field was a patch of small breakouts about 1 km (0.6 miles) upslope of Highway 130. Breakouts were also active in an area roughly 6 km (4 miles) upslope of the flow front and along the edge of the forest northeast of Puʻu ʻŌʻō.

The summit lava lake level fell from about 10 m (30 ft) during the week, and was about 45 meters (150 ft) below the rim of the Overlook crater, as of Thursday, Feb. 19.


Four earthquakes in the past week were reported felt on the Island of Hawai’i. On Monday, Feb. 16 at 12:49 p.m., a magnitude-3.2 earthquake occurred 3.6 km (2.2 mi) south of Pa’auilo at a depth of 8.8 km (5.5 mi). Later that day, at 1:40 p.m., a magnitude-3.3 earthquake occurred 4.5 km (2.8 mi) southwest of Pa’auilo at a depth of 10.2 km (6.4 mi), at 4:37 p.m., a magnitude-2.5 earthquake occurred 6.7 km (4.2 mi) northwest of Captain Cook at a depth of 13.0 km (8.1 mi). On Tuesday, Feb. 17, at 3:17 a.m., a magnitude-3.9 earthquake occurred 51.1 km (31.7 mi) west of Kailua at a depth of 12.4 km (7.7 mi).

Volcano Watch is a weekly article and activity update written by scientists at the U.S. Geological Survey`s Hawaiian Volcano Observatory.

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