Tuesday | April 21, 2015
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U.S. ranks high in world with active volcanoes, eruption-warning capability

Before Mount St. Helens erupted in 1980, most people were unaware the U.S. ranks as one of the top countries worldwide, in terms of the number of geologically young, active volcanoes. An updated review of the nation’s active volcanism from 1980 through the end of 2012, shows that 107 eruptions occurred at 32 volcanoes — mostly located in Alaska — and at least 41 episodes of unrest were observed at 13 volcanoes.

Four new eruptions have occurred in 2013 at volcanoes in Alaska — Cleveland, Pavlof and Veniaminof — and Pagan in the Commonwealth of Northern Marianas Islands. Two eruptions are continuing at Kilauea, from Halemaumau Crater at the summit and the Puu Oo vent 12 miles to the east.

Also in 2013, various signs of persistent unrest continue at Yellowstone and Long Valley calderas in Wyoming and California, respectively.

The most explosive and harmful eruption in terms of lives lost and economic effects was that of Mount St. Helens. Large explosive eruptions also occurred at Pagan (1981—1985) and Anatahan (2003) in the Commonwealth of the Northern Marianas Islands, and Spurr (1992), Augustine (1986, 2006), Kasatochi (2008), Okmok (1997, 2008), and Redoubt (1989, 2009) in Alaska.

The most voluminous lava-producing eruption since 1980 is the ongoing Kilauea eruption (1983-present), which is not showing signs of winding down.

Eruption warnings and regular information updates in the U.S. are the responsibility of the U.S. Geological Survey through the Volcano Hazards Program and its five volcano observatories, along with federal, state and university partners.

In the past 33 years, the capability of the USGS to issue warnings and updates has increased significantly for several key reasons: the astounding improvements in volcano-monitoring, computer and information technology; a dramatically increased number of monitoring networks installed on volcanoes with the highest threat in the U.S., especially in Alaska; the experience and expertise gained by scientists in understanding volcanic processes and interpreting the early signs of potential volcanic activity; and the creation of coordinated communication and emergency-response plans for use during eruptions and escalating periods of unrest.

This unprecedented capability stems from significant long-term investment by the Federal government to reduce volcanic risk in the nation after the eruption of Mount St. Helens, when funding of volcano monitoring and research increased tenfold.

In 2005, the USGS characterized this expanded monitoring and warning capability as the U.S. National Volcano Early Warning System and developed a framework for expanding the monitoring effort to include more volcanoes deemed a high threat to the nation but that are not sufficiently well-monitored to ensure detection of unrest and warnings well before any eruption might begin.

This framework spurred further investment in the NVEWS infrastructure in 2009 and 2010 through the American Recovery and Reinvestment Act in 2009 and 2010, when the USGS received $15.2 million for its Volcano Hazards Program. Today’s volcano monitoring and warning capability was significantly improved by ARRA, but — as widely reported in the media earlier this year — the effects of continuing sequestration make it difficult to maintain or improve the NVEWS.

For information about how the chronology of activity in the U.S. was determined, see “Chronology and References of Volcanic Eruptions and Selected Unrest in the United States, 1980—2008” at pubs.usgs.gov/of/2009/1118. For information about the NVEWS, see volcanoes.usgs.gov/publications/2009/nvews.php.

Kilauea activity update

A lava lake within the Halemaumau Overlook vent produced nighttime glow visible from the Jaggar Museum overlook and via HVO’s webcam during the past week. The lava lake level fluctuated a minor amount earlier in the past week, with a small deflation-inflation cycle at the summit, and had dropped to a slightly deeper level as of Thursday, as a result of a larger DI event.

On Kilauea’s east rift zone, breakouts from the Peace Day tube remain active on the coastal plain. A small ocean entry is active just east of the Hawaii Volcanoes National Park boundary; another ocean entry that was recently active within the park is now inactive. The Kahaualea 2 flow, fed from a spatter cone on the northeast edge of the Puu Oo crater, continues to advance slowly along the edge of the forest north of Puu Oo, burning vegetation. The front of the Kahaualea 2 flow this past week was 1.9 miles north of Puu Oo.

There were no earthquakes reported felt in the Hawaiian Islands during the past week.

Visit hvo.wr.usgs.gov for Kilauea, Mauna Loa and Hualalai activity updates, recent volcano photos, recent earthquakes and more; call 967-8862 for a Kilauea summary; email questions to askHVO@usgs.gov.

Volcano Watch is a weekly article and activity update written by scientists at the U.S. Geological Survey’s Hawaiian Volcano Observatory.