Photos: Mauna Loa eruption offers rare glimpse of Earth

The world's largest active volcano has erupted for the first time in 38 years, sparking excitement among scientists eager to unravel its many mysteries.

< p class="css-at9mc1 evys1bk0">Notice that Mauna Loa, the world's largest active volcano, was about to erupt - as it did this week for the first time in nearly four decades - came to the inhabitants of the Big Island of Hawaii an hour before the lava began to flow. The public authorities hastened to alert the residents. Scientists raced to predict which areas of the island could be at risk. The curious planned to observe what could become a life-long event: the exhalation of a massive mountain.

The eruption lasted for years, unmatched on a large scale by the ongoing effort to monitor the volcano with seismometers, spectrometers, tiltmeters, GPS units, and other state-of-the-art tools. "Mauna Loa is one of the best-instrumented volcanoes in the United States," said Wendy Stovall, volcanologist at the U.S. Geological Survey. Even still, so much about the inner workings of the mountain is unknown, said Dr. Stovall and other scientists.

Weston Thelen, a volcanologist from the U.S.G.S. who monitored the mountain from 2011 to 2016, said the size, mineral composition and heat all presented logistical challenges for scientists and public officials hoping to predict its movements. "Mauna Loa is a beast," he said.

With the eruption underway, Big Island researchers including Jim Kauahikaua, a volcanologist of the U.S.G.S. Hawaiian Volcano Observatory, had to find the right balance between concern for public safety, given the many unknowns, and the desire to collect data.

"Our mission Our main task is to scientifically mitigate these dangers," Dr. Kauahikaua said. "An eruption is always exciting, but we learn to temper the excitement and work professionally toward our primary mission."

So far, the eruption has posed little danger to surrounding communities - and thus provided a sense of urgency for scientists eager to unravel Mauna Loa's many mysteries. For how many weeks, from months or years will the opportunity remain available? "No one really knows how long this eruption will last," said Gabi Laske, a geophysicist at the University of California, San Diego.

< p class="css-at9mc1 evys1bk0">Dr. Thelen said: "We have we have very rare glimpses of what is happening in the volcano. If we just put people in lawn chairs at the end of the lava flow and say, "It moved a yard," we detonate it. »

An old hotspot

ImageLava near Saddle Road, a main road on the Big Island , Monday.Credit...Marco Garcia/Associated Press

ImagePlumbing system details Mauna Loa are still relatively hazy, said Weston Thelen, a volcanologist with the U.S. Geological Survey. “The closer we look, the more questions we have. and the splits can create anomalous areas in the crust and upper mantle through which rock – made molten and less dense by the heat of the planet's core – can penetrate to the surface. But the Hawaiian Islands are 2,000 miles from the nearest tectonic boundary, and their existence has puzzled geologists for centuries.