Scientists suspected the secret was buried in stone somewhere beneath Hawaii. Archipelago’s famous volcanic activityWith nearly 200,000 earthquakes now and the help of a machine learning program, Wilding and his colleagues finally found it.
In a study published Thursday in the journal chemistry, the team uncovered a collection of previously hidden magma caches that may act like the beating heart of the volcano above. It offers a possible solution to the long-standing mystery of how they travel to the surface. The study provides scientists with a valuable new window into the behavior of some of the most fickle and dangerous volcanoes on Earth.
Shallow magma reservoirs that feed Hawaiian eruptions have long been known. This is partly thanks to seismic waves being closely monitored in Hawaii by an ever-expanding network of sensors. Waves act like ultrasound on Earth. Changes in speed and trajectory while traveling through the earth tell scientists what kind of matter they’ve traveled through, and provide clues to its temperature, density, and composition.
But to truly understand the dynamics of these volcanoes, scientists need to know what happens at the interface between the mushy mantle and the solid crust. That’s what a new study finally reveals in unexpected detail.
The giant feature described in the paper consists of several elongated chambers called sills. These deep thresholds seem to react when eruptions drain magma from shallow reservoirs above. The cacophony of an earthquake is a signal that individual rooms will begin to fill with molten rock at different times, Wilding says, like “blood rushing to the heart.”
“We were just watching it and it was really shocking,” he said. Zachary Ross, a geophysicist at the California Institute of Technology. “Since then, that image has stuck in my mind.”
Ken Rubin“This is a very sophisticated study and very interesting results,” said a University of Hawaii volcanologist who was not involved in the study.
Like most of the earth, Hawaii wouldn’t exist without volcanic activity. Since time immemorial, deep-rooted fountains of superheated rock known as mantle plumes have burned down the underside of the Pacific tectonic plate. As the plates continued to move, a series of spectacular volcanoes rose above the waves, creating the chain of Hawaiian islands.
Today the chain hosts a small family of active volcanoes, including Mercury Mauna Loa and hyperactivity Kilauea both on the big island Eruption stopped at the same time this month.
Sustained seismic rumbles from an area 20 miles below the surface, southwest of Kilauea, have previously fault collection It may exist there, creating pathways for magma to travel from Hadean depths to reservoirs near the surface. And since the 1980s, a special kind of earthquake that suggests moving fluids suggests that magma is moving violently in the region. But until recently, the nature of this underground labyrinth was based more on speculation than on scientific truth.
“It was this mystery box in the mantle,” said Wilding. “We really know very little about what’s going on.”
What scientists needed was a sustained spike of earthquakes emanating from that exact region, enough to strongly illuminate that shadow zone. , things looked promising.
But the team’s lucky break came in 2018. After the Kilauea volcano had been erupting almost continuously for his 35 years, Grand finale style eruption sequence It started with a volcano. In just three months, the event produced the equivalent of 320,000 Olympic-sized pools of lava. The summit collapsed dramatically as the volcano’s shallow magma reservoir rapidly lost blood.
In an exciting plot twist, geologists recorded a shocking surge in deep seismic activity in 2019 far below the town of Pahala, located about 25 miles southwest of Kilauea. Indeed, scientists thought this was no coincidence.
The Pahala earthquake storm was an opportunity to unearth the island’s buried magmatic treasures, but scientists alone were unable to pinpoint many of the individual quakes of that cacophony.
The Caltech team didn’t want to miss a single beat of the geological drum. We input the entire seismic storm record into a machine learning program. This is a technique Ross and his colleagues have used before. Identify millions of hidden earthquakes in California. The program quickly learned what noise was unrelated to real earthquakes, identifying and characterizing thousands of earthquakes that conventional seismic signal detection programs and their human analysts would have missed. I was.
From November 2018 to April 2022, the system recorded approximately 192,000 earthquakes under Pahala. Plotting these luminous points on a map, the team was stunned to discover a stunning collection of magmatic structures – the center of a beating volcano in southern Hawaii.
Some of the quakes originated from regions 28 to 32 miles deep. These long-period earthquakes are usually vibration It is made by the movement of fluids containing magma. Most of the seismic activity occurred from regions 22 to 27 miles deep. These volcano-tectonic earthquakes—the type that occur when rocks break as faults move within volcanic regions—delineate nearly horizontal sheet-like structures, some of which are four miles long and wide. It was 3 miles.
At various times, scientists have detected surges in seismic activity within different sheets. The team speculated that these sheets were sills, magma pockets that track molten rock erupting from the lower fluid-filled regions near the peaks of the mantle plumes.
Seeking deeper connections
“This new 3D map of a key segment of Hawaii’s circulatory system is extraordinary,” he said. Jackie Kaplan Auerbach, a volcano-seismologist at Western Washington University, who was not involved in the new study. “It’s pretty amazing,” she said, that scientists can not only see this previously hidden heart, but also perceive the internal ventricular spasm.
The Pahala Sir complex is technically known as the heart, from which several arteries appear to branch off. One major pathway characterized by rock-crushing earthquakes appears to lead directly to one of Kilauea’s shallow magma reservoirs. It’s probably no coincidence that 2019 started thundering incessantly at the Sil Complex. In response, magma was sucked into the threshold to equalize the pressure.Something similar happened in Kilauea. Summary of 2020 eruptions.
Further research may help resolve the controversial question of whether Kilauea and Mauna Loa, relatively close neighbors on the surface, exist in some form. Connected at great depths.To date, little concrete evidence exists for this hypothesis, and experts generally believe that two volcanoes that is mainly independence each other’s.
New research has yet to overturn that consensus. This marks another major artery of the sill complex, again marked by rock-crushing earthquakes, streaking towards Mauna Loa. However, this stopped at a large horizontal fault, and he does not appear to have reached one of Mauna Loa’s shallow magma reservoirs.
Nor is it certain that magma is moving through any of these pathways. The situation will change if future studies detect the kind of long-term earthquakes that indicate the presence of a fluid likely to be magma.
“The results are amazing,” he said Diana RomanA geophysicist at the Carnegie Institute of Science, DC, who was not involved in this study. However, “it is still unclear whether the magma intruding in Pahala is directly feeding the Mauna Loa and Kilauea eruptions.”
Roman also studied the Pahala earthquake. co-authored by her 2021 paper They concluded that it was the result of magma penetrating into the depths, squeezing the underlying piping networks of both Mauna Loa and Kilauea, simultaneously causing unrest. is supporting But even this mapped magma web is too early to call for a more definitive link.
Still, much of Hawaii’s underworld remains unexplored, and more magmatic arteries may still be discovered, Ross said.
“What’s not glowing and still there?” he said. Every time Hawaii’s hellish surface shakes violently again, a team from Caltech is ready to shine a spotlight on it in hopes of revealing what’s hidden for now. .
