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Geology topics

J. D. Unger

Publications and source records attributed to J. D. Unger.

7 recordsLinked to original sources
USGS2006

Deep seismic sounding in northern Eurasia

For nearly 40 years, the former Soviet Union has carried out an extensive program of seismic studies of the Earth's crust and upper mantle, known as “Deep Seismic Sounding” or DSS [ Piwinskii , 1979; Zverev and Kosminskaya , 1980; Egorkin and Pavlenkova , 1981; Egorkin and Chernyshov , 1983; Scheimer and Borg , 1985]. Beginning in 1939–1940 with a series of small-scale seismic experiments near Moscow, DSS profiling has broadened into a national multiinstitutional exploration effort that has completed almost 150,000 km of profiles covering all major geological provinces of northern Eurasia [Ryaboy, 1989].

Eos, Earth and Space Science News↗
USGS1995

Silurian tectonic history of Penobscot Bay region, Maine

Early Paleozoic amalgamation of composite terranes was contemporaneous at widely separated regions that were later accreted to either ancestral North America or to Gondwana as those two continents approached each other. Peri-Gondwanan terranes formed from Late Cambrian and Early Ordovician rocks were amalgamated in the Late Ordovician and Early Silurian to form the Salinic orogenic belt. Salinic orogenic activity involved extensive thrust faulting and metamorphism, large strike-slip faults, and plutonism. In the Penobscot Bay region, Maine, the peri-Gondwanan St. Croix terrane was thrust northwest in the Silurian(?) upon middle amphibolite facies Ordovician and Early Silurian rocks of the Fredericton trough. The strike-slip faults are interpreted to either remain steep until they reach the sole of the thrust sheet or to become listric within the thrust sheet. -from Authors

Maine↗
USGS1993

Seismic survey of Lake Baikal, Siberia cruise report: RV Balkhash 25 August to 25 September 1992

Introduction A comprehensive multichannel seismic-reflection (MCS) and ocean bottom seismometer (OBS) seismic-refraction survey of Lake Baikal, Siberia was undertaken during August-September 1992 as a collaborative research project by U.S. and Russian scientists. This project was supported by funding from the U.S. Geological Survey, the U.S. National Science Foundation and the Russian Academy of Sciences. Over 2200 km of multichannel seismic-reflection data on 42 profiles and over 500 km of seismic-refraction data on 4 OBS profiles were acquired during this study. On board seismic processing facilities were utilized for quality control and demultiplexing of seismic data during the cruise. Lost survey time due to weather was about 7 days, but most planned seismic profiling was completed, including the reshooting of profiles where necessary. This seismic study was carried out on two vessels, the RV BALKHASH for MCS work and the TITOV for OBS deployments. This report summarizes the general seismic program and the operations on the BALKHASH. Operations on the TITOV are summarized in a companion report by tenBrink and others. A detailed description of the logistical and technical aspects of the seismic program, including all seismic systems, is given in the companion report by Nichols and others.

Siberia↗
USGS1974

Scientists probe Earth’s secrets at the Hawaiian Volcano Observatory

The Hawaiian Volcano Observatory (HVO) sits on the edge of Kilauea Caldera at the summit of Kilauea Volcao, one of the five volcanoes on the island of Hawaii, the largest island in the Hawaiian Islands chain. Of the five, only Kilauea and Mauna Loa have been active in the past 100 years. Before its last eruption in June 1950, Mauna Loa had erupted more frequently and copiously than Kilauea, but since then only Kilauea has been active.

Hawaii↗
USGS1973

Earthquakes near Mount St. Helens, Washington

Seismic monitoring around Mount St. Helens, Washington, for 28 days during the summer of 1970 showed that the frequency of local earthquakes was from 3 to 13 per day and very similar to the activity previously observed near Mount Rainier, Washington. The epicenters of the well-recorded earthquakes form a roughly linear pattern trending northeast from the summit area. This is the only obvious trend in the epicenter distribution. Recent geological investigations have not revealed faults or other major geological discontinuities along this trend. This pattern of epicenters seems to be approximately aligned with the remnants of five ancestral St. Helens plug domes that trend southwest from the summit region.

Washington↗