Officials on the Big Island of Hawaii are telling residents to be prepared in case the volcano erupts soon.
HONOLULU – The floor trembles and swells on Mauna Loa, the world’s largest active volcano, suggesting it may erupt. Scientists say they don’t expect it to happen right away, but officials on the Big Island of Hawaii are telling residents to be prepared should it erupt anytime soon. Here are some things you should know about the volcano.
WHERE IS MAUNA LOA?
Mauna Loa is one of five volcanoes that together make up the Big Island of Hawaii, which is the southernmost island in the Hawaiian archipelago. It’s not the tallest (that title goes to Mauna Kea), but it’s the tallest, making up about half of the island’s landmass.
It is just north of the Kilauea volcano, which is currently erupting from its summit crater. Kilauea is known for a 2018 eruption that destroyed 700 homes and spread lava flows across farms and into the ocean.
Mauna Loa last erupted 38 years ago. In written history dating back to 1843, it has erupted 33 times.
Mostly rural, the Big Island is home to cattle ranches, coffee farms, and beach resorts. It is about 200 miles (320 kilometers) south of Hawaii’s most populous island of Oahu, home to both the state capital Honolulu and the beach resort town of Waikiki.
WILL MAUNA LOA ERUP LIKE KILAUEA?
Mauna Loa’s eruptions differ from those of Kilauea in part because it is larger. Its greater elevation gives it steeper slopes, allowing lava to tumble down its slopes faster than Kilauea’s.
Because of its enormous size, it may be able to store more magma, resulting in larger lava flows if it erupts.
Frank Trusdell, a research geologist at the Hawaiian Volcano Observatory, part of the US Geological Survey, said data suggests Mauna Loa has a much larger magma reservoir than Kilauea, which could allow it to store more lava and last longer in between Eruptions to be dormant as Kilauea.
WHERE WILL MAUNA LOA BREAK OUT?
Scientists won’t know until the eruption begins. Every eruption since 1843 has started at the summit. In half the time, the volcano later began to erupt from vents at lower elevations as well. The other half of the time it only erupted in the summit caldera.
Scientists cannot predict when and where Mauna Loa will vent and erupt far in advance.
Vents generally form along the volcano’s rift zone. There the mountain splits open, the rock is cracked and relatively weak and magma can escape more easily.
An eruption from the vents in the southwest rift zone could hit residential communities, coffee farms, or coastal villages on the western side of the island. Lava could reach houses in just hours or days.
The West Side’s most populous city would be protected from an eruption of Mauna Loa by the presence of another active volcano. The broad flanks of this volcano, Hualalai, sit between the southwest rift zone of Mauna Loa and Kailua-Kona and would block any lava flowing toward the coastal community.
An eruption from the northeast rift zone could send lava toward the county seat of Hilo or other cities in eastern Hawaii. It could take weeks or months for lava to reach populated areas this side of the mountain.
Scott Rowland, a geologist at the University of Hawaii at Manoa, said there is no pattern when it comes to where an eruption will occur.
“Just because the last one was in the northeast rift zone doesn’t mean the next one will be in the southwest rift zone,” he said.
WILL MAUNA LOA EXPLODE LIKE MOUNT ST. HELEN?
57 people died at Mount St. Helens in the US state of Washington erupted in 1980 and blasted more than 1,300 feet (400 meters) from the top of the mountain. Steam, rock, and volcanic gas explode upward and outward. A plume of volcanic ash rose over 80,000 feet (24,384 meters) and rained down as far as 250 miles (400 kilometers) away.
Hawaiian volcanoes like Mauna Loa tend not to have such explosive eruptions.
That’s because their magma is hotter, drier, and more fluid, said Hannah Dietterich, a geophysicist at the US Geological Survey’s Alaska Volcano Observatory.
The magma in Mount St. Helens tends to be stickier and traps more gas, making it much more likely to explode as it rises.
The gas in the magma of Hawaiian volcanoes tends to escape, and so lava flows down the side of their mountains when they erupt.
Hawaii’s volcanoes are called shield volcanoes because successive lava flows over hundreds of thousands of years form broad mountains that resemble the shape of a warrior’s shield.
Shield volcanoes are also found in California and Idaho, as well as Iceland and the Galapagos Islands. Alaska’s Wrangell-St. Elias National Park has eight shield volcanoes including Mount Wrangell.
Volcanoes like Mount St. Helens are called composite or stratovolcanoes. Their steep, conical slopes are formed by the eruption of viscous lava flows and rock, ash, and gas. Japan’s Mount Fuji is another example of a composite volcano.
HOW DO SCIENTISTS MONITOR MAUNA LOA?
The Hawaiian Volcano Observatory has more than 60 GPS stations on Mauna Loa that take measurements to estimate the location and amount of magma accumulating beneath the surface.
Scientists use inclinometers to track long-term changes in the slope of the ground, which helps them see when the ground is rising or falling. A rapid change in inclination can indicate when an eruption will occur.
There is also a thermal webcam at the top of Mauna Loa that will detect the presence of heat. And satellite radar can track ground swelling and deflation.
Associated Press writer Mark Thiessen contributed to this report from Anchorage, Alaska.
https://www.kvue.com/article/news/national/hawaii-volcano-eruption/507-322fde7d-19ca-418f-8376-a57f68b1336c Hawaii’s largest volcano could erupt soon