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James G Moore

As a geologist with the U.S. Geological Survey, Dr. Moore has conducted pioneering research in the Sierra Nevada, Hawaii, the Philippines, the Mid-Atlantic Ridge, Mount St. Helens, Surtsey, and Lake Tahoe.

He mapped the geology of the southern Sierra Nevada in California including Sequoia and Kings Canyon National Parks and recognized a zonation of batholiths named the Quartz Diorite Line. The work revealed a major fracture system filled with igneous rock, the Independence Dike Swarm, which proved to be the key to dividing Sierran granites into two major age groups. The work also led to a model for the origin of orbicular granite and comb layering and defined the origin of giant K-feldspar crystals found in granodiorite plutons.

In 1961 he was posted as Scientist-In-Charge at the Hawaiian Volcano Observatory. He was first to recognize two giant submarine landslides on the flanks of the Hawaiian Ridge, and in 1962 served as Chief Scientist on the U.S. Coast and Geodetic Ship Pioneer, when some of the first ocean-floor photographs were taken of pillow lava. Analyses of this fresh lava quenched under pressure produced unique data on the initial gas content of magma. In the early 1970s he made the first scuba dives on active lava flows off Kilauea Volcano and documented the origin of pillow lava. In 1974 he participated in the FAMOUS project, a joint French-American diving program on the Mid-Atlantic Ridge, and completed six 9000-ft-deep dives in the submersible Alvin to map and sample young lavas. During the late 1980s he participated in the GLORIA project using sonar to map the Hawaiian Exclusive Economic Zone, which revealed several dozen massive submarine landslides on the Hawaiian Ridge. In 1995 he conducted similar sub-aqueous investigations of Lake Tahoe to determine the nature, age, and effects of a giant landslide in the lake basin.

In 1965 he was posted by President Johnson to work with Philippine scientists on the tragic explosive eruption of Taal Volcano, where giant dunes around the vent led to the concept of pyroclastic Base Surges. He also studied the ongoing 1968 explosive eruption of Mayon Volcano in the Philippines, measuring the velocity of hot block-and-ash avalanches. During 1979 he helped drill Surtsey volcano, which had grown offshore from Iceland in 1963-1967. The core revealed the nature of secondary hydrothermal minerals and that the volcano is underlain by two diatremes which extend far below the pre-volcanic ocean floor. He helped promote a 2017 redrilling of Surtsey Volcano, in which the results supported the diatreme hypothesis. In a 1999 Hawaiian drilling program, he studied core from a 3-km-deep drill hole on Mauna Loa, which showed the transition from subaerial- to submarine-erupted lava and established the degree of volcano subsidence.

During the 1980 eruption of Mount St. Helens, he measured the ongoing deformation of the volcano; afterward, he used photographs and military satellite images to define the exact timing of the May 18 events, determined the landslide volume, measured and described ash deposits, analyzed the formation of the eruption cloud, and mapped the first series of domes to fill the crater.

*Disclaimer: Listing outside positions with professional scientific organizations on this Staff Profile are for informational purposes only and do not constitute an endorsement of those professional scientific organizations or their activities by the USGS, Department of the Interior, or U.S. Government