Eruption is a natural lab for volcanologists


Welcome to the 4th annual Volcano Awareness month! Throughout January 2013, the Hawaiian Volcano Observatory (HVO), in cooperation with Hawaii Volcanoes National Park, University of Hawaii at Hilo, Edith Kanaka‘ole Foundation, and Hawaii County Civil Defense, is offering a series of public talks about Hawaii’s volcanoes. More information about these events is posted on HVO’s website at hvo.wr.usgs.gov.

As during past Volcano Awareness Months, this column will focus on a theme for the month of January. Over the next four weeks, we will explore some of the most scientifically important eruptions that have occurred in Hawaii since HVO was established in 1912 — specifically, what we have learned from these eruptions and why they are important.

Since this month marks the 30th anniversary of the start of Kilauea’s current East Rift Zone eruption (as described in last week’s column), it’s only fitting that we begin with that eruption, which started on Jan. 3, 1983.

After initial fountaining from a series of fissures, activity gradually focused on a single vent and built the Pu‘u ‘O‘o cone. In 1986, the eruption shifted about 2 miles downrift, building the Kupaianaha lava shield and, in 1990, devastating the community of Kalapana. Activity returned to Pu‘u ‘O‘o during 1992-2007, but moved about 1.3 miles downrift during 2007-2011. Since September 2011, Pu‘u ‘O‘o has again been the dominant source of lava flows.

This eruption has provided a cornucopia of insights into how Kilauea works. The sheer duration of the eruption has allowed for careful and sustained study of many aspects of volcanic activity, from the movement of magma underground to the emission of gases into the atmosphere. Some of the most important new insights concern the eruption and emplacement of lava flows.

While both pahoehoe and ‘a‘a lava flows have been observed for centuries, the 30-year-long eruption has provided an opportunity to study, in detail, the complex formation of an entire lava flow field, instead of just a single flow. Inflation of pahoehoe sheets has been thoroughly documented, leading to a better understanding of how lava tubes form and how lava interacts with preexisting topography.

This information has a direct impact on estimation of lava flow hazards, including the prediction of lava flow paths, and has been used to interpret the development of lava flows on other planets, such as Mars.

The eruption has spanned a revolution in the development of volcanological tools, for example, the measurement of ground deformation. In 1983, motion of the ground’s surface was monitored using ground-based methods that required many people and lots of time to collect a limited amount of data. Now, deformation is monitored by satellite, as well as by automated, continuous sensors on the ground.

Many other methods of measurement, such as detecting gas emissions and thermal anomalies, have similarly advanced. The net effect of these developments is better resolution (in time and space) of volcanic activity. In other words, changes in volcanic activity that might not even have been detected in 1983 can be thoroughly documented in 2013.

Since 1983, improvements in our ability to integrate different kinds of geophysical, geochemical and geological data have enhanced our monitoring capability.

Such integrations have led to a better understanding of the eruption, as well as to better forecasts of future activity. For example, by combining gas emission and deformation measurements, seismic data and observations of heightened eruptive activity in 2003-2007, HVO scientists concluded that the amount of magma supplied to Kilauea more than doubled during that period. This surge in supply may have been indirectly responsible for the 2008 start of the ongoing summit eruption.

Of course, it’s not possible to fully document all of the scientific advances that have been made by studying Kilauea’s current East Rift Zone eruption. The take-home message, rather, is that volcanology has enjoyed tremendous advancements in the past 30 years, thanks in no small part to data collected at Kilauea.

Tune in next week, when we turn our attention to the most recent eruption of Mauna Loa. Until then, you’re invited to attend one or more of this week’s Volcano Awareness Month talks. Details are available at hvo.wr.usgs.gov or by calling 967-8844.

Kilauea activity update

A lava lake within the Halema‘uma‘u Overlook vent produced nighttime glow that was visible from the Jaggar Museum overlook and via HVO’s webcam during the past week. The inflation phase of a deflation-inflation cycle (DI event) at Kilauea’s summit started on Jan. 5. The lava lake had risen to within 130 feet of the Halema‘uma‘u Crater floor before the DI event switched to deflation on Thursday, Jan. 10, when the lava lake began to drop. The lava level will likely continue falling until inflation resumes.

There were two felt earthquakes reported on the Island of Hawaii in the past week. On Jan. 4 at 3:42 p.m., a magnitude-2.9 earthquake occurred 4 miles southwest of Ookala at a depth of 7 miles. On Jan. 5, at 4:37 a.m., a magnitude-4.6 earthquake occurred 6 miles west of Kalapana at a depth of 6 miles.

Volcano Watch is a weekly column written by the scientists at the USGS Hawaiian Volcano Observatory.

 

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