Mauna Loa lava flows mapped
By Kevin Dayton
Advertiser Big Island Bureau
New maps of lava flows on Mauna Loa have been compiled to allow people living on the world's largest volcano to make educated guesses about where future flows may end up.
Frank Trusdell, volcanologist with the U.S. Geological Survey, said the maps were generated to help civil-defense officials decide early in Mauna Loa's eruptions where to focus their warnings, evacuation planning and other preparations.
View the maps online
The maps are available on the Internet so that when lava next emerges from Mauna Loa, homeowners can also estimate the paths it likely will follow downslope.
Mauna Loa last erupted in 1984. Scientists noticed an inflating of the caldera called Moku'aweoweo last year after nearly a decade of deflation, a sign that probably indicates swelling of the magma reservoir within the volcano.
Similar swelling was observed before the past two eruptions at Mauna Loa. More recently the swelling has slowed, but experts believe it is only a matter of time until the volcano erupts again. Mauna Loa's longest period without an eruption was 25 years, from 1950 to 1975.
Trusdell said the lava flow mapping project began before the caldera swelling was observed, but the maps should help civil-defense officials prepare for future eruptions. The project was financed by the U.S. Geological Survey, Hawai'i County and the Federal Emergency Management Administration.
Scientists have identified more than 500 lava flows originating from Mauna Loa's summit area, its two rift zones and vents outside those zones.
After a year of compiling data on past flows, they generated nine maps of 18 inundation zones that allow people to estimate which areas will be affected by eruptions based on where the lava originates.
As an example, if there were a Mauna Loa eruption under way in the volcano's northeast rift zone at elevations from 10,800 feet to about 8,000 feet, Trusdell said that would tend to steer lava into the Kaumana area above Hilo as it did during the 1880-1881 eruption.
For Hilo it would take days or weeks for lava to reach populated areas, but in other areas such as the southwest rift zone in South Kona or Ka'u, lava from Mauna Loa can flow to the ocean in a matter of hours.
Scientists advise people to make contingency plans because if an eruption occurs in some areas it may be too late for residents to go home and grab possessions, Trusdell said.
The maps cover inundation zones that include Kaumana, Waiakea, and the Volcano-Mountain View area; Kapapala; Pahala, Punalu'u and Wood Valley; Na'alehu; Ka Lae; Hawaiian Ocean View Estates, Kapu'a and Miloli'i; Ho'okena, Ka'ohe and Ka'apuna; Honaunau and Kealakekua; and Puako.
The maps are at geopubs.wr.usgs.gov/docs/wrgis/mf-map.html.
Reach Kevin Dayton at (808) 935-3916 or kdayton@honoluluadvertiser.com.
