Editor’s note: Volcano Watch is a weekly column provided by the scientists at the Hawaiian Volcano Observatory headquartered at the summit of Kilauea Volcano. See below for a link to HVO’s website and previous Volcano Watch columns.
Every year about this time, we write about the chemistry of lava erupting from Kīlauea Volcano.
In previous articles, we have discussed the significance of monitoring subtle changes in the chemical composition of new lava. With specialized equipment, we can monitor the composition of crystals grown within the lava, the uncrystalized glass that quenched around them at sampling time, and the tiny remnants of the parent magma frozen within the crystals (melt inclusions) to assess conditions of magma storage and transport within Kīlauea Volcano.
The crystals and glass can tell us the amount of time that was spent and the depth through which this magma traversed before being erupted at the Earth’s surface. Analyzing the melt inclusions can tell us about the source of the magma batch before it started its upward journey. This information, along with volcano seismicity, deformation, gas emissions and eruptive behavior, is the core of our multi-faceted approach to understanding and forecasting the behavior of ongoing summit and east rift zone eruptions of Kīlauea.
For the last decade, near-vent lava samples collected by HVO geologists were shipped to the Cascade Volcano Observatory in Vancouver, Wash., where they were carefully examined and processed. This has worked pretty well, because most of the analytical work is accomplished using specialized lab facilities on the Mainland. However, it was usually weeks to months before lab results were available.
When there are sudden and significant changes in eruptive activity, quick results are needed to determine whether the lava composition has changed. For this reason, HVO started a cooperative program with the Geology Department at the University of Hawai‘i at Hilo 18 months ago, designed to share some routine responsibilities related to petrologic monitoring of Kīlauea, while training and educating prospective scientists at the same time.
Under the direction of Professor Cheryl Gansecki, students and staff at UH-Hilo have been trained in HVO’s protocol for the processing and preparation of lava samples. The UH-Hilo group has also added their own methods and instrumentation to the effort. The project is funded by the US Geological Survey through a cooperative agreement between the Hawaiian Volcano Observatory and UH-Hilo, administered by the Center for the Study of Active Volcanoes.
Now, when lava is sampled in and around Puʻu ʻŌʻō, or Pele’s hair is collected at Halema‘uma‘u, the samples are sent directly to the UH-Hilo Geology Department. There, a geologist provides a brief summary of character and appearance of samples, along with assessments of the abundance of any crystals observed in the raw samples. Any apparent changes in the eruption samples, or the lack of changes, are immediately communicated to HVO scientists.
Portions of larger samples are carefully separated for more specialized analysis in mainland laboratories, and then rapid trace-element (elements only present in minute amounts in lava) analyses are performed using an x-ray fluorescence (XRF) instrument at UH-Hilo to detect possible changes in the magma source. After that, finely polished grain-mounts of carefully selected crystals and lava fragments are prepared for detailed analysis on the mainland, using very narrow X-ray beams capable of resolving chemical changes finer than 50 microns or micrometers (0.002 in).
Finally, a scanning electron microscope at UHH is used to image crystal textures and to obtain qualitative analyses for mineral identification compositions and glasses in Kīlauea grain mounts and melt inclusions. This work by UH-Hilo provides an eloquent array of targets for quick quantitative analysis of Kīlauea eruption samples while enabling efficient use of more specialized instruments available only on the Mainland.
Results so far indicate that the program is working well, confirming that no significant changes have occurred in the magma/lava source. The HVO-UH-Hilo partnership provides a local collaborator for routine hazard-related HVO petrology tasks while providing new opportunities and experience for staff and students at the university.
This addition to our eruption-monitoring routine has added advantages of rapid turnaround of lava-chemistry information for immediate use in monitoring and forecasting eruptive activity in Hawai‘i.
Kīlauea activity update
A lava lake within Halema‘uma‘u produced nighttime glow that was visible via HVO’s Webcam during the past week. As of Thursday, April 3, the lava level for the week had been relatively steady, generally staying around 46–48 m (151–157 ft) below the rim of the Overlook crater.
On Kīlauea’s East Rift Zone, the Kahauale‘a 2 flow continued to be active northeast of Pu‘u ‘Ō‘ō. The active flow front was 8.2 km (5.1 miles) northeast of the vent on Pu‘u ‘Ō‘ō when last measured on Friday, March 21, and no significant advancement has occurred since. Webcam images indicate that small, lava-sparked forest fires continue to burn.
There were no felt earthquakes in the past week on the island of Hawai‘i.
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Visit the HVO website (http://hvo.wr.usgs.gov) for past Volcano Awareness Month articles and current Kīlauea, Mauna Loa, and Hualālai activity updates, recent volcano photos, recent earthquakes, and more; call (808) 967-8862 for a Kīlauea summary; email questions to [email protected].
Volcano Watch (http://hvo.wr.usgs.gov/volcanowatch/) is a weekly article and activity update written by scientists at the US Geological Survey`s Hawaiian Volcano Observatory
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