Volcano Watch — Two erupting volcanoes cause most harm in 2006

Activity in the past year consisted chiefly of fresh lava covering older flows of the eruption and building new land into the ocean. The eruption also produced an average of more than 1,500 tonnes of sulfur dioxide gas each day into the air, but the flows did not lead to evacuations or otherwise impact the daily lives of island residents.

The island of Hawai`i had another "safe" eruption year, with Kīlauea sending lava flows primarily onto land of Hawai`i Volcanoes National Park.

Such was not the case with at least two other volcanoes in the world in 2006, Tungurahua in Ecuador and Mayon in the Philippines.

An average of about 60 volcanic eruptions occurs each year in the world based on eruption records of the past 20-30 years. A Weekly Volcanic Activity Report supported by the Smithsonian Institution's Global Volcanism Program and the U.S. Geological Survey is a good source of preliminary information of the world's volcano activity. The weekly reports are archived according to date, volcano, and region (see http://www.volcano.si.edu/reports/usgs/index.cfm).

A review of these preliminary reports shows that about 48 volcanoes generated some type of eruption in 2006. Ten of these volcanoes were erupting at the end of 2005, including Kīlauea. About another 20 volcanoes showed signs of unrest that was observed by scientists or reported by residents and visitors. These volcanoes did not actually erupt, but their rumblings did lead to a few evacuations as a precautionary measure.

Six volcanoes erupted in Papua New Guinea and Indonesia, compared with 13 in 2005. Four volcanoes erupted in Japan.

The continuing eruption of Tungurahua volcano in Ecuador and the short-lived eruption of Mount Mayon in the Philippines produced large eruptions that led to the evacuation of more than 30,000 people combined, but the evacuations occurred for different reasons.

In late August, about a month after Tungurahua volcano produced strong explosions, lava flows, and pyroclastic flows, several United Nations agencies and other organizations provided aid for an estimated 19,000 people forced into shelters from many villages on the flanks of the volcano. This year's activity has impacted the local residents more than anytime since the volcano became active in 1999.

In late December, four months after Mayon erupted lava flows and deposited ash in stream valleys leading from the volcano, Typhoon Durian triggered deadly mudflows from the volcano. Fatalities from the mud flows were estimated at more than a thousand people and more than 15,000 people from 12 different villages were forced to evacuate their homes and communities.

Seven volcanoes erupted in the U.S. and the Commonwealth of the Northern Mariana Islands (CNMI), including Kīlauea, Anatahan, and Pagan volcanoes. At least 5 others only showed signs of unrest.

The first historical eruption of Fourpeaked volcano in Alaska occurred suddenly in late September, sending an ash plume 6 km (20,000 ft.) high; the volcano is still restless today. As far as scientists know, the most recent large eruption was more than 10,000 years ago. If other eruptions have occurred, they weren't large enough to leave an ash layer or deposit for scientists to trace back to the volcano and date.

When such explosive activity occurs at a long quiet volcano, particularly one in a remote, rugged location, it's a challenge to quickly install the instruments necessary to monitor the volcano. Many scientists of the U.S. Geological Survey have responded to the activity at Fourpeaked volcano, including several from the Hawaiian Volcano Observatory.

The Hawaiian Volcano Observatory wishes a safe and prosperous 2007 to the scientists and other volcano watchers across the globe tracking the world's volcanoes. We especially wish this for communities living in the shadow of volcanoes that either erupted in 2006 or will erupt in 2007.

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Volcano Activity Update

This past week, activity levels at the summit of Kīlauea Volcano have remained at background levels. The number of earthquakes located in the summit area is low (usually less than 10 per day that are large enough to locate).

Eruptive activity at Pu`u `O`o continues. On clear nights, glow is visible from several vents within the crater. Lava is fed through the PKK lava tube from its source on the southwest flank of Pu`u `O`o to the ocean. About 1 kilometer south of Pu`u `O`o, the Campout flow branches off from the PKK tube. The PKK and Campout tubes feed two widely separated ocean entries, at East Lae`apuki and East Ka`ili`ili, respectively. Both entries are located inside Hawaii Volcanoes National Park.

In the last week, intermittent breakouts from the Campout tube have occurred on the slope of Pulama pali and on the coastal plain. On December 20, a new arm of the Campout flow reached the ocean at Kamokuna, about midway between the two older entries. The new entry lasted less than a day, but started up again on December 26 and was still active as of January 3.

Access to the sea cliff near the ocean entries is closed, due to significant hazards. The surrounding area, however, is open. If you visit the eruption site, check with the rangers for current updates, and remember to carry lots of water when venturing out onto the flow field.

There were no earthquakes beneath Hawai`i Island reported felt within the past week.

Mauna Loa is not erupting. During the past week, earthquake activity remained low beneath the volcano's summit (one earthquake was located). Extension of distances between locations spanning the summit, indicating inflation, continues at slow rates.