Those who knew him said he was most proud of creating the Center for the Study of Active Volcanoes at the University of Hawai'i-Hilo, a cooperative effort between the university and the observatory. The center was established in 1989 to provide training and information on volcanic and natural hazards that occur in Hawai'i and elsewhere. Its international training course in volcano hazards monitoring has instructed nearly 100 scientists from 23 nations in techniques of monitoring active volcanoes and forecasting eruptions.

"Bob Decker was a great scientist, but in addition, he always emphasized the importance of public education, and of communication between volcanologists and government," said Darcy Bevens, the center's educational specialist.

She said his enthusiasm was contagious, that he loved teaching and was able to explain "complicated scientific ideas in simple language, both in the field and classroom."

While at the Hawaiian Volcano Observatory, Decker started writing the weekly "Volcano Watch" column in response to daily inquires about the work being done at the facility. The column continues today, written by different staff members.

With his wife, Barbara, Decker also wrote travel and science books, including the textbook "Volcanoes" and the 2001 book "Volcanoes in America's National Parks."

In that book, the Deckers, who have a house at Kawaihae, described their lifelong passion for volcanoes: "Volcanoes assail the senses. They are beautiful in repose and awesome in eruption; they hiss and roar; they smell of brimstone. Their heat warms, their fires consume; they are the homes of gods and goddesses."

From 1975 to 1979, he served as the president of the International Association of Volcanology and Chemistry of the Earth's Interior, and was credited with introducing innovative technologies, such as using lasers to measure the change in distance across Moku'aweoweo caldera on Mauna Loa.

Jim Kauahikaua, current scientist-in-charge at Hawaiian Volcano Observatory, said that because of Decker's early work, scientists have a record of the caldera's widening before the last two eruptions in 1975 and 1984. He said the data are crucial to forecasting Mauna Loa's eruptions.

Longtime observatory staff like to tell the story of a going-away party held for Decker the evening of March 24, 1984, before he moved to California. The staff had recognized the signs of an imminent Mauna Loa eruption in 1983 and joked about it in a skit performed at the party. Three hours later, early on the morning of March 25, the volcano erupted, and when contacted at home, Decker had to be convinced it wasn't a joke.

Decker was born March 11, 1927. No services are planned. Donations may be sent to the Robert Decker Memorial Scholarship at the Center for the Study of Active Volcanoes, UH-Hilo, 200 W. Kawili St., Hilo, HI 96720.