When Mount St. Helens erupted explosively in 1980, most people were unaware that the U.S. ranks as one of the top countries in the world in the number of geologically young, active volcanoes. An updated review of the nation’s active
When Mount St. Helens erupted explosively in 1980, most people were unaware that the U.S. ranks as one of the top countries in the world in the number of geologically young, active volcanoes. An updated review of the nation’s active volcanism from 1980 through the end of 2012, however, shows that 107 eruptions occurred at 32 volcanoes (most of which are located in Alaska), and at least 41 episodes of unrest were observed at 13 volcanoes.
So far in 2013, four new eruptions have occurred at volcanoes in Alaska (Cleveland, Pavlof, and Veniaminof) and the Commonwealth of Northern Marianas Islands (Pagan), and two eruptions are continuing in Hawaii at Kilauea Volcano from Halema‘uma‘u Crater at the summit and the Pu‘u ‘O‘o vent 12 miles to the east.
Also in 2013, various signs of persistent unrest continue at two of the largest volcanoes in the U.S., 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 United States are the responsibility of the U.S. Geological Survey (USGS) through the Volcano Hazards Program(VHP) 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 (NVEWS), 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 (ARRA) 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, http://pubs.usgs.gov/of/2009/1118/. For information about the NVEWS, see http://volcanoes.usgs.gov/publications/2009/nvews.php.
Kilauea activity update A lava lake within the Halema‘uma‘u Overlook vent produced nighttime glow that was 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 (DI) cycle at the summit, and had dropped to a slightly deeper level as of Thursday, July 25, 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 Kahauale‘a 2 flow, fed from a spatter cone on the northeast edge of the Pu‘u ‘O‘o crater, continues to advance slowly along the edge of the forest north of Pu‘u ‘O‘o, burning vegetation. The front of the Kahauale‘a 2 flow this past week was 1.9 miles north of Pu‘u ‘O‘o.
There were no earthquakes reported felt in the Hawaiian Islands during the past week.
Visit the HVO website (http://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 (http://hvo.wr.usgs.gov/volcanowatch/) is a weekly article and activity update written by scientists at the U.S. Geological Survey’s Hawaiian Volcano Observatory.
