January 18, 2007

A weekly feature provided by scientists at the Hawaiian Volcano Observatory.

Hawai`i earthquakes get a new manager

Dave Wilson in Mexico with Colima Volcano erupting ash and steam in the background.

Seismologist Dave Wilson started work this week as the new manager of the HVO seismic monitoring network. He will take over the job vacated when Stuart Koyanagi moved to the Pacific Tsunami Warning Center in late 2005.

Dave earned his Ph.D. from New Mexico Institute of Mining and Technology studying the deep structure of the Colorado Plateau and the Rio Grande Rift in the western U.S. In his research, he addressed the question of why these landscapes have such high elevations by looking at what's under them. At such great depths in the earth, the easiest way to study structures is to examine the way the waves from distant earthquakes travel through them. The answer was not simple but was, in part, the result of differences in the upper mantle (lower densities and higher temperatures) that allowed the crust to float higher than in other areas of the U.S.

For the past two years, Dave has studied the general plate tectonics of the area of Mexico around Colima Volcano while pursuing a post-doc appointment at the University of Texas at Austin. Colima is one of the so-called "Ring of Fire" volcanoes around the Pacific rim that are located over subducting plates. Colima Volcano continues to be active and occasionally erupts steam and ash. One of the questions Dave was trying to answer here was whether any abnormalities in the subduction of the Pacific Plate beneath Colima might help explain its eruptions.

Dave's wife, Jennifer, is a geologist who has studied how groundwater flows through fractured rocks in the southwestern U.S. She examined the fractures and "deformation bands" in welded, several-million-year-old pyroclastic flows and found that groundwater was drawn to these abnormalities. This work was the main part of her Ph.D. dissertation at New Mexico Tech.

We might consider it prophetic that Dave has been indirectly working on volcanoes for the last several years. While at New Mexico Tech, Dave helped fellow student Mario Ruiz locate seismic tremor sources in the vicinity of Mount Erebus, an active volcano sporting a lava lake in Antarctica. Particularly puzzling were the "tremor" sources that were distant from the volcano. Normally, tremor around a volcano is an indicator of magma movement underground, and the sources are right under the volcano. In their case, the puzzling tremor was linked to icebergs scraping the sea bottom nearby.

Dave and Hawai`i were connected early in two ways involving a baritone `ukulele and a late honeymoon. Dave's mom acquired the `ukulele during her college years. This, in itself, is not unusual, except that it happened in Indiana. The late honeymoon belonged to his parents, who rendezvoused in Honolulu while his dad served in the Navy in Vietnam.

At any rate, Dave (with `ukulele), Jennifer, daughter, Kaya, and dog, Tick, have arrived and are settling into Hawai`i. Aside from a couple of short trips, none of the Wilsons have spent much time in Hawai`i before, but they are looking forward to the change of pace. Dave has expressed an interest in returning to geology and taking advantage of the more family-oriented atmosphere here. They also look forward to getting into plenty of outdoor activities. We hope you will join us in welcoming the Wilsons to Hawai`i.

Activity update

This past week, activity levels at the summit of Kilauea Volcano have remained at background levels. The number of earthquakes located in the summit area is low (usually less than 10 per day are large enough to locate).

Eruptive activity at Pu`u `O`o continues. On clear nights, glow is visible from several vents within the crater. Lava is fed through the PKK lava tube from its source on the southwest flank of Pu`u `O`o to the ocean. About 1 kilometer south of Pu`u `O`o, the Campout flow branches off from the PKK tube. The PKK and Campout tubes feed two widely separated ocean entries, at East Lae`apuki and East Ka`ili`ili, respectively. Both entries are located inside Hawaii Volcanoes National Park.

A third entry, fed by an offshoot of the Campout flow, has been active since December 26. It is located at Kamokuna, about midway between the two older entries. In the last week, intermittent breakouts from the Campout tube have continued on the slope of Pulama pali and on the coastal plain near Kamokuna.

Access to the sea cliff near the ocean entries is closed, due to significant hazards. The surrounding area, however, is open. If you visit the eruption site, check with the rangers for current updates, and remember to carry lots of water when venturing out onto the flow field.

There were no earthquakes beneath Hawai`i Island reported felt within the past week.

Mauna Loa is not erupting. During the past week, earthquake activity remained low beneath the volcano's summit (one earthquake was located). Extension of distances between locations spanning the summit, indicating inflation, continues at slow rates.

Visit our Web site (hvo.wr.usgs.gov) for daily Kilauea eruption updates and nearly real-time Hawai`i earthquake information.