In 2018, lava from Hawaii’s Kīlauea volcano blanketed 35 sq. kilometers of land and worn out greater than 700 buildings, in one of many island’s most harmful and extensively studied eruptions. Because of knowledge from that eruption, researchers say they’ve a brand new strategy to calculate the depth of flowing lava primarily based on peculiar waves within the red-hot rock. The method might enhance forecasts of how far the flows will journey—a vital issue for gauging the hazard and warning folks in hurt’s method.
“The concept is sort of good,” says volcanologist Simone Tarquini of Italy’s Nationwide Institute of Geophysics and Volcanology, who was not concerned within the research. The method, he says, represents “a brand-new device to be added to the usual toolbox of volcanologists.”
Some volcanoes explode violently into the air, whereas others—resembling Kīlauea and its kin in Hawaii—principally gush lava down their sides. When a brand new eruption begins, emergency managers have to know the place that lava will go. The form of the terrain, the chemistry of the lava, and its quantity can all have an effect on the trail of destruction, says Hannah Dietterich, a geophysicist with the U.S. Geological Survey.
However estimating the quantity of a lava stream is difficult as a result of it’s harmful and impractical to measure the depth of a stream. It’s not doable to easily drop a measuring stick into quick lava (though volcanologists in Hawaii as soon as tried from helicopters).
To get at this measurement, Dietterich turned to a time-honored Hawaiian custom: catching waves. Years earlier, colleagues of hers had observed that some lava flows featured “standing” waves, evenly spaced waves that seem like immobile. In line with hydraulic concept, measuring such waves ought to permit the depth of the stream to be calculated. Wouldn’t it work for lava?
The 2018 eruption supplied a wonderful alternative to search out out. As a result of the eruption occurred in a residential neighborhood, Dietterich and others may drive near the lava, which was racing previous at 54 kilometers per hour. The air reeked of sulfur and was tinged with burning asphalt. The bottom was scorching sufficient to soften sneakers. Not lengthy after lava started to stream, they noticed standing waves close to the supply, referred to as the vent. “If you had been standing proper there on the facet of the lava stream, these waves towered above you,” Dietterich says.
Laser scanners on helicopters discovered that the waves had been 3 meters tall from trough to peak. Drones swooped in to clock the stream’s velocity. Primarily based on these knowledge, Dietterich and her colleagues calculated the lava was 5 meters deep on common and that its common stream was 250 cubic meters per second. That’s quick sufficient to fill an Olympic swimming pool each 9 seconds. When the eruption was over, they analyzed 3D pictures of the drained lava channel and located the calculated depth was a detailed match, they report within the September difficulty of the Journal of Geophysical Analysis: Earth Floor.
Dietterich says these measurements could possibly be added to the usual forecast mannequin as an impartial test. Even aerial pictures of standing waves can be useful to estimate depth and stream price, she says.
Nonetheless, standing waves solely happen in fast-flowing lava and never in stickier, slower lava. Which means the usefulness of monitoring them can be restricted to sure volcanoes, resembling these in Hawaii or Iceland. It may be related for Nyiragongo, a harmful volcano within the Democratic Republic of the Congo that killed dozens in a 2021 eruption. It would even be doable to make use of the identical method to estimate the stream charges of different fast-flowing hazards that exhibit standing waves, resembling volcanic mud flows or particles flows throughout floods, Dietterich says.
Tarquini notes that pictures or video of standing waves in such disasters wouldn’t assist with real-time hazard evaluation, as a result of these occasions sometimes solely final for an hour or much less. However it will be useful in finding out what causes these flows to behave in sure methods. “A greater understanding of a bodily phenomenon all the time implies a higher means to cope with it,” he says.
One other key distinction between water and lava, Tarquini notes, is that the properties of molten rock change dramatically because it cools. As soon as lava solidifies, it will possibly alter the form of the channel itself. After September 2018, the slopes of Kīlauea had been as soon as once more secure, strong rock. However the volcano remains to be energetic, and it’ll definitely spill lava once more.