Decker, renown vulcanologist, dies at 78

The staff at the Hawaii Volcano Observatory (HVO) are mourning the passing of Dr. Robert (Bob) Decker, who was Scientist-in-Charge from 1979-1984. Decker, 78, died at home in Mariposa, California, on June 11 after a sudden, unexpected downturn in his fight against cancer. Decker shaped much of the organizational structure of the current Hawaiian Volcano Observatory staff, overseeing the volcano and earthquake monitoring and the technical staff providing the equipment, research, and administrative support.

Due to daily inquiries about the observatory’s work from the public, Decker started writing a weekly column for Hawaii Tribune-Herald that we have continued as “Volcano Watch” more than 20 years later. He also taught courses at UH Hilo and Manoa on the geology of Hawai`i.

At a time when mail delivery to Hawai`i was slower and e-mail had not been invented yet, Decker saw the need for a comprehensive collection of all the scientific papers written about Hawai`i’s volcanoes on site to facilitate research at HVO. This collection has since grown and evolved into a searchable bibliographic database of nearly 14,000 records that he himself returned time and again to use.

One of his visionary accomplishments, and the one of which he was most proud, was the creation of the Center for the Study of Active Volcanoes, in collaboration with HVO, at the University of Hawai`i at Hilo. Here, international students come to study and observe active volcanoes first-hand, learn how to monitor them, and mitigate the hazards of living with them. When they return to their countries, they are able to set up monitoring systems that reduce threats from volcanic and seismic hazards to their own communities.

While Decker had a major influence on HVO and the volcanology of Hawai`i, he was also internationally recognized for pioneering physical volcanology work in Alaska, the Cascades, Central America, Iceland, and Indonesia. From 1975-1979, he served as the president of the International Association of Volcanology and Chemistry of the Earth’s Interior (IAVCEI), the primary organization of volcanologists worldwide.

We are fortunate that Decker chose to work in Hawai`i and introduced so many innovative technologies. For example, he started using lasers to measure the change in distance across Moku`aweoweo caldera on Mauna Loa in 1965. Because of his early start, we have a record of the caldera’s widening before the last two eruptions in 1975 and 1984. These data are crucial to scientists’ confidence in forecasting the next Mauna Loa eruption.

While HVO scientists do not believe that an eruption is imminent, they know that it is coming. When Mauna Loa does erupt, Decker’s many legacies will be present in the efforts to monitor and ultimately forecast the eruption.

One of the best stories about Decker concerns the start of the 1984 Mauna Loa eruption. He had already led the recognition of the beginning and subsequent monitoring of the ongoing eruption of Kilauea. He and the staff also recognized the signs of an imminent Mauna Loa eruption in 1983. But his “tour of duty” was up in early 1984 and he had already made plans to move to California.

Decker’s going-away festivities the evening of March 24, 1984, easily met the HVO standard for memorable parties. Normally not known for their dramatic abilities, staff members enjoy roasting their peers in skits at going-away parties. One of the skits was about an eruption of Mauna Loa on the eve of his departure. Fun was had by all and everyone departed in very good spirits.

It was easy to see why Decker thought the staff was continuing the joke when he was awakened only three hours later early on the morning of March 25 and notified that Mauna Loa was indeed erupting! The rest of the revelers were also pressed into service at 3:00 a.m. to monitor and document the eruption.

Decker’s coordination of the work of HVO, Hawai`i Civil Defense, and Hawai`i Volcanoes National Park, among others, during the 1984 Mauna Loa eruption serves as a model of how hazardous eruptions here should be handled to maximize scientific understanding while addressing public concerns and media demands. His good will and professionalism made him a consummate teacher and gracious host in the service of the public. His friends and colleagues in Hawai`i bid him a final “aloha.”

Activity Update

Eruptive activity at Pu`u `O`o continues. On clear nights, glow is visible from several vents within the crater and on the southwest side of the cone.

The PKK lava tube continues to produce intermittent surface flows from above the top of Pulama pali to the ocean. Two ocean entries were active as of June 23. The largest is at East Lae`apuki, with a smaller entry at East Kamoamoa. Surface flows are intermittently active inland of the entries. The East Lae`apuki entry is the closest activity to the end of Chain of Craters Road, in Hawai`i Volcanoes National Park, and is located about 4.5 km (3 miles) from the ranger shed.

Expect a 2-hour walk each way and bring lots of water. Stay well back from the sea cliff, regardless of whether there is an active ocean entry or not. Remember—the beaches that sometimes form next to an active bench are just as dangerous as the bench itself. Stay off both, and heed the National Park warning signs.

During the week ending June 22, no earthquakes were reported felt on Hawai`i Island.

Mauna Loa is not erupting. During the week ending June 22, ten earthquakes were recorded beneath the summit area. Two were deep and long-period in nature. Inflation continues, but at a slightly reduced rate over the last few weeks.

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

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