American Geophysical Union conference highlights Hawaiian volcanism

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Every December, an interesting phenomenon occurs in downtown San Francisco.

A massive horde of strange-looking visitors—slightly out of place with their boots, fleece jackets, poster tubes and preponderance of bearded men and make-up-free women—descends on the city with a singular purpose. If you ever want to see 20,000 geoscientists in the same place, go to the American Geophysical Union fall meeting, the largest Earth science conference in the world.

The meeting topics are divided into 27 disciplines, such as Atmospheric Sciences, Natural Hazards, and Planetary Sciences. These are further subdivided into sessions, which have a particular focus within that discipline. At any one time during the week-long meeting, dozens of sessions may be going on, providing a dizzying selection of talks and science posters to view.

In this year's meeting, the Hawaiian Volcano Observatory organized a session for the Volcanology, Geochemistry and Petrology discipline. The session was titled "100 years of observing Hawaiian volcanoes" and was devoted to all aspects of Hawaiian volcanism. This session was the first of many activities commemorating the 100th anniversary of HVO; the entire list of centennial activities can be found on the HVO Web site.

The session opened with a broad historical overview by Scientist-in-Charge Jim Kauahikaua, describing the founding of HVO by Thomas Jaggar in 1912 and HVO's contributions to the scientific community since that time. Jeff Sutton then summarized the past hundred years of gas geochemistry studies in Hawai‘i, which depended heavily on "nasal chromatography" (that is, the human nose) in the early days but now uses a wide array of advanced instruments. Frank Trusdell described how Mauna Loa and Kīlauea may be "dueling" volcanoes—his data suggest that when one of these volcanoes is highly active, the other tends to quiet down.

Tim Orr gave a talk noting a repeating pattern of behavior that precedes changes in the eruption around Pu‘u ‘Ō‘ō. This pattern of changes, which includes increasing ground tilt and small earthquake swarms, helped HVO anticipate and prepare for some of the recent activity this year, such as the Kamoamoa eruption. Matt Patrick summarized the current behavior of the Halema‘uma‘u lava lake and contrasted it with the lava lake present at Kīlauea in the early 1900s.

Paul Okubo described how seismic monitoring has been a workhorse tool for studying Hawaiian volcanoes, and how HVO has participated in improving the instruments and analytical techniques used by the seismologic community. Mike Poland then presented a comprehensive picture of Kīlauea's magma "plumbing" system—the network of reservoirs and conduits that supply lava at the surface.

Beyond HVO, scientists from many institutions presented research on Hawaiian volcanism. Dave Clague, a former HVO Scientist-in-Charge now at the Monterey Bay Aquarium Research Institute, provided an overview of submarine volcanism in Hawai‘i. Richard Fiske, another HVO alumnus, now at the Smithsonian Institution, described a large, explosive eruption from Kīlauea's summit around A.D. 900. Numerous other talks and posters on Hawaiian volcanoes were presented by researchers from other USGS offices, as well as universities, such as University of Hawai‘i at Manoa, Michigan Tech, University of Oregon, and University of Wisconsin-Madison, among others.

One talk in the HVO session garnered the attention of the national news, which is impressive, considering that multitudes of presenters arrive clamoring for media exposure. HVO's Don Swanson presented data showing that Kīlauea's activity over the last 2,500 years has alternated between periods of explosive and effusive (lava flow) activity. Currently, we are in a period of effusive activity, with lava peacefully circulating in the summit vent and erupting from Pu‘u ‘Ō‘ō on the east rift zone.

Swanson showed that other periods in Kīlauea's history, hundreds of years ago, were characterized by violent explosive activity that covered the summit area in layers of ash and blocks. His work highlighted the fact that, although Kīlauea is known now for its peaceful activity, it has had a very violent past that could recur at some time in the future.

Science at HVO began prior to the theory of modern plate tectonics, before modern computing, and before the proliferation of highly specialized geophysical and geochemical instruments. The Hawaiian volcanoes session at the AGU conference reminds us just how far the science, and our understanding of volcanic and earthquake hazards, has come in 100 years.

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Volcano Activity Update

A lava lake present within the Halema‘uma‘u Overlook vent over the past week resulted in night-time glow that was visible from the Jaggar Museum overlook. The lake, which is about 75–100 m (245–330 ft) below the floor of Halema‘uma‘u Crater and visible by HVO's Webcam, rose and fell slightly during the week in response to deflation-inflation cycles. A collapse of a portion of the vent crater wall triggered a small explosion at the lava lake on Wednesday, December 14, that threw spatter onto the rim of Halema‘uma‘u Crater.

On Kīlauea's east rift zone, surface lava flows continued to be active on the coastal plain, entering the ocean at West Ka‘ili‘ili, within the National Park. The ocean entry has had a weak, wispy plume. Flows continued to be active in the abandoned Royal Gardens subdivision over the past week, as well. The flows traveled through a lava tube fed by the September 21 fissure on the upper east flank of the Pu‘u ‘Ō‘ō cone.

One earthquake beneath Hawai‘i Island was reported felt this past week. A magnitude-3.7 earthquake occurred at 2:22 p.m., HST, on Thursday, December 15, 2011, and was located 12 km (8 mi) southwest of Kīlauea Summit at a depth of 31 km (19 mi).