# Volcano Watch — Monitoring Kīlauea's eruption: how close to the action is close enough?

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Hawaii is often described as the ideal setting for studying active volcanic processes. After all, where else can you find a "drive in" volcano that provides all the amenities that volcanologists want: hot fresh lava; swelling, quaking ground; and the delicate fragrance of sulfurous fumes emanating from abundant fissures and vents?

A testimony to this scientifically fertile part of the Earth is a bibliographic database maintained at HVO that, at last count, included 12,253 publications related to Hawaiian volcanism. Nearly half of these articles were added since the current eruption began 20 years ago.

The road to publication for volcano literature is not always a clear one, though. As surely as lava flows have blocked the lower part of Chain of Craters Road to traffic, they have also literally obstructed some ongoing studies of Kīlauea's eruption. A few of us at HVO were 'co-miserating' on this topic just the other day.

An observatory geophysicist recounts a recently-hurried trip to rescue monitoring instruments in the path of a lava-ignited forest fire. A geologist displays what remains of a computerized datalogger encased in fresh pahoehoe during a rapid overflow event on the Mother's Day lava tube. Another staffer points gloomily to the precise location on a map where a continuous gas monitoring site became "permanently installed" under several meters of liquid rock, leaving not even a hint on the surface of what lies beneath.

Discussions like these emphasize how difficult it can be to plan careful experiments that have the best chance to answer good scientific questions-preferably several questions at once. A guiding thought to experimental design echoes Einstein's words, "Things should be made simple as possible-but no simpler." As you might imagine, conducting the study that will lead to the 12,254th publication about volcanic processes in the Hawaii database involves a balancing act.

On one hand, the scientific questions we ask, and sometimes the instruments involved in gathering the answers, become increasingly complex as we learn more and more about subsurface processes. On the other hand, the reality is that when a lava flow meets an instrument in a plastic box, data collection stops abruptly. And in these days of "fiscally-responsible" earth science, there isn't much room for error.

In spite of the above complexities, the news is not all bad. Technology really has helped us remotely monitor volcanic activity better and faster, and, in some instances, cheaper. Off-the-shelf GPS and tiltmeter instruments are continuously measuring changes in shape of the ground surface at Kīlauea and Mauna Loa more precisely than ever before. These improvements led us last year to detect a nearly simultaneous swelling event on Mauna Loa and a pulse of magma delivered to Puu Oo on Kīlauea. Improved reliability, cost, and technical enhancements in seismic and volcanic gas monitoring instruments have provided opportunities to practically expand our spatial coverage and test new techniques and ideas.

Finally, the computer hardware and software that allow us to graphically visualize the many datastreams simultaneously as volcanic events are occurring have markedly enhanced our understanding of the relationship between magma transport, ground-surface deformation, earthquakes, eruption rate, and gas release.

But with all these techno-improvements that we depend on these days for remotely monitoring volcanic processes come the reminder to stay in touch with the volcano. Satellite images, remote video cameras, tiltmeters, seismometers, and gas sensors are just a supplement to direct field observations, not a replacement. We as geoscientists must also continue to use all of our senses as well as our brains to do the job right. And along those lines, does anybody out there know how to get data out of a half-baked datalogger?

### Volcano Activity Update

Eruptive activity at the Puu Oo vent of Kīlauea Volcano continued unabated during the past week. The long and narrow tongue of lava reported in last week's update as moving down Pulama pali west of the main Mother's Day flow, reached the highway at 10:05 a.m. on Thursday, February 13. It crossed the highway an hour later and was heading to the seacoast west of Wilipea. This surface flow is the cause of the fire burning the native forest. Lava also continues to flow in the Mother's Day tube system down to the ocean entry at West Highcastle.

The public should be aware that the ocean entry areas could collapse at any time, potentially generating large explosions in the process. The steam clouds rising from the entry areas are highly acidic and laced with glass particles. The National Park Service has erected a rope barricade to delineate the edge of the restricted area. Do not venture beyond this rope boundary onto the lava deltas and benches. Even the intervening beaches are susceptible to large waves suddenly generated during delta collapse; these beaches should be avoided.

Two earthquakes were reported felt during the past week. Residents of South Kona, Kau, Puna, Hilo, and Papaikou felt an earthquake at 10:53 p.m. on February 6. The magnitude-3.3 earthquake was located 28 km (17 mi) south of Kaena Point at a depth of 40 km (24 mi). On February 11 at 7:54 p.m., a resident of Pahala felt the earth move. The magnitude-1.7 earthquake was located 2 km (1.2 mi) east of Pahala at a depth of 6 km (3.6 mi).

Mauna Loa is not erupting. The summit region continues to inflate, though the rate of inflation has slowed gradually during the past month or two. The earthquake activity is low, with only two earthquakes located in the summit area during the last seven days.