Mauna Loa swelling detected
By Hugh Clark
Advertiser Big Island Bureau
VOLCANO, Hawai'i — Mauna Loa, the world's largest volcano, has been quiet for 18 1/2 years. Now it appears to be stirring again, scientists report.
In their weekly "Volcano Report," dated today, Hawaiian Volcano Observatory geologists report that Mauna Loa began inflating again on Mother's Day.
Readings by the Global Positioning System show not only swelling at the 13,679-foot summit but also a spreading outward on the northeast rift facing Puna and Hilo between the 10,000 and 13,000-foot elevations.
"The next eruption is a question of time, not if. There will likely be one, but when and where we do not yet know," said Donald Swanson, the scientist in charge of the observatory.
Technically, the caldera at Moku'aweoweo has widened by four-fifths of an inch since May 12.
"This is small stuff, indeed, but it does mark a noticeable, perhaps notable, change from the preceding nine years," Swanson said.
By using satellite Global Positioning System measurements to compare data with that of the older "tilt" stations scattered on the mountain, the swelling observations have been confirmed, the scientists' report said.
"The summit area is swelling, slowly but measurably," Swanson said.
Because instruments are not recording earthquakes yet, Swanson predicted that an eruption is some time off. When earthquakes begin, an eruption is likely within months, history shows.
In June 1950, Mauna Loa rolled lava off the South Kona coast for 23 days, destroying villages and ranches and forcing relocation that took years to legally sort out.
In July 1975, a short eruption near the summit covered minor roadways and cut off activities for several days at the Mauna Loa Observatory that studies global air pollution around the clock. That observatory, dating from 1956, is at the 11,140-foot elevation.
A March 1984 Mauna Loa eruption caused much alarm but no major damage as lava rolled for miles toward Hilo for 22 days, nearing the Kulani State Prison.
Overall, Mauna Loa has been far less active in the past half-century than in its previously recorded 106 years when 35 eruptions were logged from 1843 to 1949.
By contrast, eruptions were less frequent in the 19th century at neighboring Kilauea to the southeast. Now the frequency of eruptions at Mauna Loa and Kilauea is reversed: Kilauea has erupted 29 times since 1959.
The current Pu'u 'O'o eruption on Kilauea's flank is the longest ever recorded — 19 3/4 years and counting.
Swanson characterized this weekend's information about the swelling at Mauna Loa as being aimed at "awareness and a reminder to people we are due for another eruption."
It should not be construed as a warning now, Swanson said. "We want people to know a change has taken place." He said a Mauna Loa update will become a part of each "Volcano Watch" starting next weekend.
In response to the present inflation, Stanford University — using a National Science Foundation grant — plans to install more GPS equipment in the next few months at a cost of up to $20,000 per unit.
Swanson said his staff feels the "seismic coverage is good and able to detect any increase ... " of earthquakes.
Typically, volcanoes swell much like a balloon. Then they begin to shake from a few earthquakes daily, building to several hundred daily until lava bursts from a crack in the surface.
Only then can scientists develop a good sense of who may be in the path of the lava flow.
Swanson said for now no one should do anything but keep well informed.
