USGS HVO Press Release — A new view of Kīlauea Volcano's explosive past

Don Swanson, a geologist with the U.S. Geological Survey's Hawaiian Volcano Observatory, will give the free presentation on Kīlauea's explosive history at 7:00 p.m. in the University Classroom Building, Room 100, on the UH–Hilo main campus, 200 W. Kawili Street, in Hilo. A map of the campus is online: http://hilo.hawaii.edu/images/maps/main_campus_map.pdf.

For the past two centuries, Kīlauea has erupted gentle lava flows and infrequent high lava fountains—activity that has destroyed property but has not been particularly hazardous to people, except on rare occasions. But Swanson's collaborative study with geologists from the Smithsonian Institution and the University of Hawai‘i at Mānoa has revealed that Kīlauea is not always so benign.

According to Swanson, during the past 2,500 years, Kīlauea's volcanic activity has alternated between periods of dominantly effusive and dominantly explosive eruptions. The research shows that effusive activity, like that of Kīlauea's current ongoing east-rift-zone eruption, makes up only 40 percent of the volcano's eruptive history, and periods dominated by explosive eruptions from a deep caldera make up 60 percent of the time.

"Research like that of Dr. Swanson's on the eruption history of Kīlauea underscores the importance of painstaking analysis of the rock record in order to get a more representative view of true geologic hazards as compared with what our limited human experience might lead us to believe," explained USGS director Marcia McNutt. "The USGS invests similar efforts to decipher the long-term geologic record of infrequent but devastating west coast tsunamis and earthquakes to overcome the very short human history in the western hemisphere."

Swanson says this surprising finding dispels a long-held notion that Kīlauea's past explosive eruptions were just blips that only briefly punctuated otherwise long and monotonous periods of lava flow eruptions. Instead, the two periods of explosive eruptions in the past 2,500 years lasted 300 and 1,200 years, respectively. This has profound implications for public safety once the next period of explosive activity begins.

"At this time, however, there is no indication that Kīlauea's next explosive period will occur any time soon," Swanson adds, "so there is no reason to not visit Kīlauea and enjoy the volcano's current effusive eruption of lava flows."

Swanson will share how he and his colleagues made these recent findings and will discuss Kīlauea's explosive past in his talk at UH-Hilo. He will also distribute copies of a newly published USGS Fact Sheet (Kīlauea—An Explosive Volcano in Hawai‘i) that he and his colleagues wrote. The Fact Sheet can also be read online at http://pubs.usgs.gov/fs/2011/3064/.
Swanson's presentation is one of many programs offered by HVO during Hawai‘i Island's third annual Volcano Awareness Month (January 2012). For more information about this talk and other Volcano Awareness Month events, visit the HVO website at hvo.wr.usgs.gov or call (808) 967-8844.

Daily updates about ongoing eruptions, recent images and videos of summit and East Rift Zone volcanic activity, maps, and data about recent earthquakes in Hawaii are posted on the HVO website at https://volcanoes.usgs.gov/observatories/hvo. 

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