clucas-zenk@westhawaiitoday.com
BY CAROLYN LUCAS-ZENK | WEST HAWAII TODAY
Sometimes, the youngest gets all the attention and a duel is evident, even when it comes to Hawaii volcanoes.
That is what Frank Trusdell, a Hawaiian Volcano Observatory geologist, explained during his presentation Wednesday evening in the packed amphitheater at Puuhonua o Honaunau National Historical Park.
Kilauea has been erupting for 29 years and is ever noticed. However, it seems nobody is talking about the 800-pound gorilla: Mauna Loa, Trusdell said.
Still active and the largest volcano on Earth, Mauna Loa poses a bigger threat because of its capability of disrupting lives and commerce islandwide. Furthermore, it has erupted 33 times since 1843, producing lava flows that have covered extensive areas on the volcano’s flanks and reaching the ocean along the island’s south, west and northwest coasts, Trusdell said.
When it blows again, Mauna Loa will be more dangerous than Kilauea because it produces greater amounts of lava, has steep slopes and its large, fast-moving flows can reach the ocean in hours, Trusdell said.
So, when will Mauna Loa rumble to life again? Hawaiian Volcano Observatory scientists can’t say for sure, but Trusdell has a theory that “Mauna Loa and Kilauea may be dueling volcanoes.”
Data suggests the volcanoes “appear to be inversely correlated.” When one of these volcanoes is highly active, the other tends to quiet down, he said.
What Trusdell is further proposing is the eruptive activity at one volcano may affect eruptions at the other because of factors relating to magma supply, volcanic plumbing and Mauna Loa’s asymmetrical flank motion.
“When the rift zones of Kilauea, and in turn its south flank, are active, Mauna Loa’s tendency to erupt is diminished,” he said. “Kilauea’s rift zones help drive the south flank seaward as Mauna Loa inflates its flank. Consequently, asymmetrical spreading occurs on Mauna Loa resulting in dilation of the shallow magma storage centers, ultimately decreasing the pressure of magma and lessening its ability to erupt.”
His hypothesis is simple: “Mauna Loa may erupt when Kilauea stops erupting or there’s an increase in magma supple enough to overcome its flank movement.”
The good news, scientists are ready for Mauna Loa’s next move. Mapping of Mauna Loa’s surface lava flows have helped identify more than 500 flows originating from the summit area, rift zones and radial vents. The past flows show the approximate pathways of future flows, which may originate in similar locations, Trusdell said.
The observatory used the mapped lava flows to construct nine maps depicting 18 inundation zones on Mauna Loa. Each zone reflects a segment of the volcano that could send flows in its direction. Civil Defense uses the maps to facilitate effective and efficient emergency responses, deciding how and where to deploy resources. The maps are available online at hvo.wr.usgs.gov.
“The key to the future is to look at the past,” Trusdell said.
clucas-zenk@westhawaiitoday.com