Unified Interior Regions

A "Volcano Watch" article several weeks ago indicated changes occurring atop Mauna Loa. Specifically, global positioning system (GPS) receivers on Mauna Loa are showing that after eight years of steady contraction, extension is again occurring across the summit. Over 2 cm of the 7 cm lost to contraction since 1993 has been regained in the last five months.

Recent visitors to the coastal eruption site, especially those unwise enough to approach the flow margins where lava is encroaching on vegetation, are being greeted by a sometimes underrated volcanic hazard-the "methane" explosion.

In the Volcano Watch article two weeks ago, we broke the news that the summit area of Mauna Loa is swelling for the first time since 1993. If this trend continues, we're on track for the next eruption.

Many streams of lava entering the ocean are shattered to bits in the surf zone. These loose fragments gradually build layers of rubble on the steep submarine slope. The resulting nearshore submarine deposits are complexly interbedded lava flows and fragments ranging in size from boulders to tiny shards of glass and minerals.

Skylight, Kīlauea Volcano, Hawai‘i.

Mauna Loa has gone 18.5 years without eruption--the second longest dry spell since detailed records begin in 1843. The longest period without eruption lasted 25 years, between 1950 and 1975. Clearly the past 52 years have been much less active than the previous 107.

In early August, Pago volcano, on the central coast of New Britain Island, suddenly began exploding rocks and volcanic ash into the air. Thousands of nearby residents quickly left their homes and work to escape possible injury or death.

Recent work sheds light on Mauna Loa's magmatic plumbing. The U.S. Geological Survey has embarked on scientific investigations of the plumbing system of Mauna Loa in cooperation with researchers from University of Washington and University of North Carolina.

Luckily, Hawai`i experiences volcanic ash much less often than it does lava flows. When it comes, though, it can be anything from a nuisance to a disaster for those beneath the falling ash. The most recent ash fall, from Halemaumau in 1924, was minor but affected residents from Maku`u to Pahala. The latest major ash fall, in 1790, resulted from explosions at the summit of Kilauea.

"Please do not let this rain dampen your spirits," Senator Daniel Inouye urged the gathering on a misty, breezy Volcano morning.

Big Island residents have long contended with the threat of tsunami. The central Pacific is, unfortunately, ground zero for many of the world's most destructive seismic sea waves.