Plumbing the depths of Hawaii's volcanoes

Are you still trying to find that special holiday gift for the volcanologist in your life? If so, you’ve come to the right place. The mini-UV spectrometer is an exciting new tool that is revolutionizing the way we measure the release of gases trapped in magma as it rises up to the surface from deep underground. And although you won’t find them yet at your local True Value Hardware or Radio Shack, the mini-spec is nonetheless an excellent example of a high-tech development that really is cheaper, smaller, and faster.

To better appreciate this new tool, it is useful to understand the old one. For the past 23 years at HVO, we have used a spectrometer called the COSPEC to measure the emission rate of noxious sulfur dioxide gas (SO2) from Halemaumau and, beginning in 1983, from the east rift eruption site. The COSPEC was developed in Canada in the mid-1970s to remotely measure pollution from industrial smokestacks.

For these many years in Hawai`i, we have measured the SO2 coming from our volcanic smokestack by strapping the forty-pound behemoth onto a sturdy platform placed in the passenger seat of our field car. Once each week, we drive the instrument along the road downwind of Halemaumau Crater and Pu`u `O`o cone, beneath the gas plume. The vertically directed COSPEC measures the amount of ultraviolet energy absorbed as sunlight passes through the plume. From the amount of energy absorbed and the wind speed, we compute the SO2 emission rate.

Gas emission rates have become a valuable part of understanding changes of pressure, temperature, and compositional conditions deep in the volcano. They have improved our understanding of how volcanoes work. Additionally, the many volcano observatories worldwide that use COSPECs have come to recognize the effects that volcanic emissions have on the environment and on human health.

The new mini-UV spectrometer, using the same basic principles of physics, but miniaturized by advances in solid-state opto-electronics, promises to shift the art and science of gas measurement into overdrive. While the COSPEC costs as much as a Humvee, is the size of a large ice chest, and weighs as much as a big bag of dog chow, the mini-UV spec is available at the cost of a fancy mountain bike and is the weight and size of a packaged macaroni and cheese dinner.

We at HVO have been working with colleagues from the University of Hawai`i (UH) to adapt the mini-UV spec, dubbed “Flyspec” owing to its small size, to the unique environment of Hawai`i’s volcanoes. And although the Flyspec represents new and better technology, we have been careful to rigorously compare our old-fashioned, vehicle-based COSPEC measurements side-by-side with those made with the new Flyspec. We have, in the process of this transition, adopted some of the superior features of the venerable COSPEC. As a result, the new instrument system is one that incorporates the best attributes of both machines.

Because of the small scale of the Flyspec, we’re able to study gas release in ways that we hadn’t considered until recently. With the judicious application of duct tape, we’ve made Flyspec measurements from a car, tripod, backpack and a helicopter. Most recently, we began an experiment, with our UH collaborators, to make continuous measurements of the gas plume from Pu`u `O`o, by placing the Flyspec beneath the plume and controlling the solar-powered instrument by radio-modem from HVO. The results thus far are encouraging.

Numerous gas geochemists working at volcanoes worldwide are exploring the potential of this new tool. For instance, colleagues at Montserrat Volcano Observatory employ a clever combination of two automated instruments to quantify SO2 from Soufriere Hills Volcano. Where human resource is plentiful, eruptive conditions amenable, but roads uncooperative, investigators have taped the mini-spec and a GPS antenna to their hard hats and proceeded on foot. So consider giving a Flyspec this holiday season to your favorite volcanologist. It’s the ultimate gas geek gift!

Activity Update

Eruptive activity at the Pu`u `O`o vent of Kilauea Volcano continued unabated during the past week. The main action was centered at the rootless shield complex near the top of the Mother’s Day flow where seven active areas were observed. The various vents within Pu`u `O`o crater were occasionally active this week, but no flows emanated from the West Gap Pit vent located immediately outside the crater. No active flows are on Pulama pali or the coastal flat below Paliuli. No lava is entering the ocean.

One earthquake was reported felt in the week ending on December 4. In the midst of a thunderous electrical storm on Tuesday, December 2, a resident of Volcano felt the earth move. The earthquake responsible was a magnitude-3.1 event that occurred at 3:21 p.m. and was located 8 km (4.8 mi) northwest of Ka`ena Point at a depth of 10 km (6 mi).

Mauna Loa is not erupting. The summit region continues to inflate. Seismic activity remains very low, with only one earthquake located in the summit area during the last seven days. Visit our website for daily volcano updates and nearly real-time earthquake information.

This article was written by scientists at the U.S. Geological Survey’s Hawaiian Volcano Observatory and is republished by with permission.

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