# Volcano Watch — Kīlauea's latest activity rates special session at international meeting

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Last weekend, seven staff members of the U.S. Geological Survey's Hawaiian Volcano Observatory (HVO) fled the stormy weather of the Big Island for the sunny, if chilly climes of San Francisco. The purpose of their trip was to participate in an annual meeting held by the American Geophysical Union.

Welcome to AGU, San Francisco!

(Public domain.)

This is the scientific conference most heavily attended by the volcanologists in the U.S. Every year, the number of scientists who descend on San Francisco to present their latest research at the December meeting increases. This year's meeting was expected to draw a crowd of over 15,000 researchers, teachers, and students. Only a small percentage of these are volcanologists, of course. The topics covered at the meeting include atmospheric, oceanic, and planetary sciences, global climate change, study of the earth's interior, and many others. The value of such a diverse range of subjects at a single meeting is that it gives researchers a chance to learn about new advances and techniques in other disciplines that may be applicable to their own specialty.

For the second year in a row, natural events on the Big Island were the subject of a special session at the meeting. Last year's topic was the October 2006 damaging earthquakes at Kiholo Bay and Mahukona. This year, it was the latest eruptive activity at Kīlauea. Kīlauea, as one of the world's most active volcanoes, has a large international following. In the world of volcanology, any news from Hawaii's volcanoes is always of interest.

HVO scientists Tim Orr and Mike Poland were co-conveners of the special session, which was entitled, "Mechanisms and consequences of the Father's Day intrusion at Kīlauea Volcano, Hawaii."

HVO geologists Tim Orr and Don Swanson, seismologist Dave Wilson, geophysicist Mike Poland, and gas geochemist Jeff Sutton all gave presentations describing and analyzing the recent events at Kīlauea that began with the Father's Day intrusion in June and culminated in the ongoing July 21 fissure eruption downrift of Puu Oo.

The Kīlauea session included presentations not only by USGS researchers and our academic colleagues from the University of Hawaii at Manoa and Hilo, but also by scientists from numerous other universities, ranging from Stanford and Scripps Institution of Oceanography all the way to the University of Miami.

Kīlauea was not the only Hawaiian volcano of interest at the meeting. HVO geologist Frank Trusdell was invited to give a talk on his work in assessing lava flow hazards from Mauna Loa. The use of GIS (geographical information system) technology has greatly facilitated our ability to provide hazard analysis based on the extensive geologic mapping on Mauna Loa.

Trusdell presented the results of this analysis, including lava flow inundation maps, which provide a tool for gauging which path a lava flow will follow once an eruption begins. He also discussed ongoing work on determining lava-flow recurrence intervals for various areas of the volcano and using these to determine the probability of lava-flow inundation. The goal of this work is to provide a better guide for planning by emergency managers and the public.

HVO's gas geochemist Tamar Elias did not attend the meeting (she's helping to hold down the fort at the observatory), but she did submit a poster. Her topic was the use of a portable monitoring system for carbon dioxide and hydrogen sulfide to assess toxic gas hazards at Yellowstone National Park. The system was developed at HVO and deployed at Yellowstone after the mysterious death of five bison in 2004. Her topic is an example of how technology and knowledge are shared amongst the volcanology community.

For those of us stationed in the middle of the Pacific, the chance to share information face-to-face with other volcanologists from around the world is essential to broadening our scientific horizons and often leads to fruitful collaborations that benefit us all.

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### Volcano Activity Update

The July 21 eruption continues to supply lava from eruptive fissure D, 2.3 km (1.4 mi) northeast of Puu Oo. For the last several months, this lava was directed entirely into a perched channel, consisting of separate pools often separated by bridges of cooled lava. At dawn on November 21, lava began to erupt directly from fissure D, outside the perched channel, creating the Thanksgiving Eve breakout (TEB) flow. Lava supply to the original perched channel has been, in part, redirected through this new outlet, cutting off supply to the eastward tube which had been feeding flows in the vicinity of Puu Kiai through much of November.

The TEB flow has built itself vertically and laterally over the last several weeks and has not surpassed the maximum along-flow distance of 2 km (1.2 mi), which it reached in the first few days of its emplacement. Most of the activity on the TEB flow has been within 800 m (0.5 mi) of the fissure and has consisted of numerous short, migrating channels and scattered breakouts. At its outlet above fissure D, the TEB lava has built a shield that is now approximately 15 m (50 ft) above the pre-breakout surface. The original perched channel has been intermittently active since the TEB flow began, with alternating overflows and lava level drops indicating repeated filling and draining. During the most recent over flight, lava had nearly filled Pond 1, and Pond 3 was overflowing on all sides. Lava has not recently reoccupied Pond 4. A wide area of short seeps on the east side of the perched channel was also observed on the flight.

On the night of December 7, incandescence was observed in webcam images in Puu Oo for the first time since August 31. The incandescence was very minor in size and intensity and originated from two distinct sources in the eastern portion of the crater. Incandescence was noted again on the night of December 8 but was absent the following three nights. As in years past, Puu Oo likely is serving as a large chimney, beneath which lava is stored briefly and degassed substantially enroute to the erupting fissure. Sloughing of Puu Oo into its own crater since late August has left numerous fresh cracks on the north rim and south flank of the cone.

Mauna Loa is not erupting. No earthquakes were located beneath the summit in the past week. Extension between locations spanning the summit, indicating inflation, continues at steady, slow rates, which have slowed further since May 2007.

Two earthquakes were reported felt on Hawaii Island within the past week. The largest was a magnitude-4.0 earthquake that occurred at 6:31 a.m., H.s.t, on Monday, December 10, 46 km (29 mi) west of Kawaihae at a depth of 32 km (20 mi). A magnitude-2.3 earthquake occurred at 10:27 a.m., H.s.t., on Wednesday, December 12, 5 km (3 miles) north of Opihikao at a depth of 1.5 km (0.9 miles).