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Facts about Mauna Loa

March 25, 2014 - 9:16am

- Mauna Loa is the world’s largest active volcano.

- It extends 13,697 feet above sea level and about 3,100 feet below sea level.

- Its name means “long mountain” in Hawaiian.

- Mauna Loa covers more than 50 percent of Hawaii Island, extending into Hilo, most of the southern portion of the island and toward Kiholo Bay in North Kona.

- It’s 500 times greater in volume than Mt. Rainier, the picturesque volcano in Washington state.

- Mauna Loa is so huge that it actually causes the Pacific plate it is residing on to sag under the weight of the volcano.

- Mauna Loa is one of five Hawaii Island volcanoes. The others are Kohala, Mauna Kea, Hualalai and Kilauea — the latter three remain active today.

- Mauna Loa remains in the shield stage and features a caldera — Mokuaweoweo — at the summit some 3.7-by-1.9 miles — much larger than Kilauea’s 1.2-by-1.9 miles. It also has two rift zones, one extending to the northeast the other to the southwest.

- The volcano also has the capability to pump out a lot more lava than Kilauea. Kilauea erupts 0.2 to 0.5 million cubic meters each day while Mauna Loa puts out 12 million cubic meters per day.

-Geologists have studied data and used radiocarbon dating to determine how many times Mauna Loa has erupted during the past 30,000 years. About 35 percent of all the lava on Mauna Loa has been dated with 500 lava flows have been mapped and 300 flows radiocarbon dated.

- The oldest rocks on Mauna Loa have been dated back between 100,000 and 200,000 years ago.

- About 98 percent of the volcano’s surface is covered with lava flows less than 10,000 years old.

- Over the past 3,000 years, Mauna Loa has erupted once every six years and evidence of four explosive events have been found. Since written records began, the volcano has erupted about once every five years, he said.

- Mauna Loa has erupted 33 times since 1843, which is when written records of volcanic eruptions began post European contact.

- In 1950, lava erupted from a fissure on Mauna Loa’s southwest rift zone, at an elevation of almost 10,000 feet, crossing Highway 11 in three places and destroying about two dozen structures before reaching the South Kona shoreline about three hours later.

- In 1984, Mauna Loa last erupted, sending lava within 4.5 miles of Hilo during an eruption between March 25 and April 15.

- Scientists estimate, depending on the location of the actual eruption on Mauna Loa, it would take the lava about 29 hours to reach the shoreline below the Hawaiian Ocean View Estates subdivision of Ka‘u, as little as three hours to reach the South Kona shoreline, eight days to reach Kiholo Bay and some 280 days to reach Hilo Bay.

- The USGS monitors Mauna Loa using numerous seismic, GPS and tilt stations positioned on its flanks. When unrest is detected, usually a swarm of earthquakes greater than magnitude 1.8, scientists notify emergency officials and increase monitoring efforts.