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At least 199 records · Page 11Linked to original sources

Seismology at the Australian National University; an interview with Anton L. Hales

Dr. Anton L. Hales is a leading seismologist who has just retired as Director of the Research School of Earth Sciences at the Australian National University (ANU), Canberra. Prior to that, he headed the Geosciences Division at the University of Texas at Dallas, and, before that, he was Director of the Bernard Price Institute of Geophysical Research at the University of the Witwatersrand Johannesburg, South Africa. he is about to step down as President of the International Geodynamics Commission. Dr. Hales' research has involved marine geophysics, the travel times of seismic waves, and the structure of the Earth's crust and upper mantle.

Earthquake Information Bulletin (USGS)↗

Continuous monitoring of Mount St. Helens Volcano

Day by day monitoring of the Mount St. Helens Volcano. These are four scenarios, very different scenarios, that can occur in a average week at Mount St. Helens. Ranging from eruptions of gas and to steam to eruptions of ash and pyroclastic flows to even calm days. This example of monitoring illustrates the differences from day to day volcanic activities at Mount St. Helens.

Washington↗

Charles F. Richter; an interview

Charles F. Richter, renowned seismologist, is a professor emeritus at the California Institue of techonology (Caltech). He is best known to the public for the Richter magnitude scale; but he is equally recognized in the scientific community for many other contributions to seismology including his books Elementary Seismology (1958) and Seismicity of the Earth (coauthored in 1954 with Beno Gutenberg).

Earthquake Information Bulletin (USGS)↗

Sociological aspects of earthquake prediction

Henry Spall talked recently with Denis Mileti who is in the Department of Sociology, Colorado State University, Fort Collins, Colo. Dr. Mileti is a sociologst involved with research programs that study the socioeconomic impact of earthquake prediction.

Earthquake Information Bulletin (USGS)↗

Predicting rock bursts in mines

In terms of lives lost, rock bursts in underground mines can be as hazardous as earthquakes on the surface. So it is not surprising that fo the last 40 years the U.S Bureau of Mines has been using seismic methods for detecting areas in underground mines where there is a high differential stress which could lead to structural instability of the rock mass being excavated. The microseismic method relies on observational data, amply demonstrated in laboratory experiments, that acoustic noise occurs in rocks subjected to high differential stresses. Acoustic emission becomes most pronounced as the breaking strength of the rock is reached. Laboratory studies have shown that the acoustic emission is linked with the release of stored strain energy as the rock mass undergoes small-scale adjustments such as the formation of cracks. Studies in actual mines have shown that acoustic noises often precede failure of rock masses in rock bursts or in coal bumps. Seismologists are, therefore, very interested in whether these results can be applied to large-scale failures; that is, earthquakes. An active research program in predicting rock bursts in mines is being conducted by Brian T. Brady and his colleagues at the U.S Bureau of Mines, Denver Colo.

Earthquake Information Bulletin (USGS)↗

Earthquake research in the Soviet Union

Henry Spall talked recently with Robert L. Wesson, the new Chief, Office of Earthquake Studies at the U.S Geological Survey National Center, Reston, Va. Wesson has spent altogether almost 1 year in the U.S.S.R, and 6 months of that time in the Garm area of Soviet Tadzhikistan in 1974.

Earthquake Information Bulletin (USGS)↗

Earthquake prediction research at the Seismological Laboratory, California Institute of Technology

The Seismological Laboratory at the California Institute of Techonology (Caltech) was founded in 1928 as a result of a study by the Carnegie Institue of Washington. The study was based primarily on a 1916 report by H. O. Wood which recommended that a network of seismic stations be established in southern California. In 1929, the Carnegie Advisory Committee sponsored a conference at Caltech involving world authorities in seismology (fig. 1). Shortly thereafter, Beno Gutenberg was appointed to work at the Seismological Laboratory, although it was not until 1947 that he was formally names as director. He was succeeded in 1957 by Frank Press (now the President's Science Advisor) and in 1967 by Don Anderson. Much of the present research at the laboratory involves disciplines that did not exist 20 years ago. They included studies of the free oscillations of the Earth after a great earthquake, studies of the properties of rocks and minerals at high temperatures and pressures, construction of synthetic seismograms, and planetary seismology. Nevertheless, basic earthquake-related information has always been of consuming interest to the public and the media in this part of California (fig. 2.). So it is not surprising that earthquake prediction continues to be a significant reserach program at the laboratory. Several of the current spectrum of projects related to prediction are discussed below.

Earthquake Information Bulletin (USGS)↗

Gilbert White talks about natural hazards

Dr. Gilbert White is Director of the Institute of Behavioral Science at the University of Colorado, Boulder, where he is responsible for natural Hazards Research and Applications Information Center supported by the National Science Foundation. He served in the Executive Office of the president in 1941-42, on the Federal Flood Control Policy Task Force in 1964-65, and on the U.S Geological Survey Advisory Panel on Earthquake Studies. Dr. White has authored five books on the social and economic aspects of natural resources, including water supply and river development, and on floods and other natural hazards.

Earthquake Information Bulletin (USGS)↗

Clarence Allen talks about the responsibilities in earthquake prediction

Dr. Clarence R. Allen is professor of geology and geophysics at the California Institute of Technology. He has been a member of advisory panels to the Executive Office of the President, National Academy of Sciences, National Science Foundation, U.S Geological Survey, UNESCO, California State Mining and Geology Board, and the California Department of Water Resources. Dr. Allen has been President of both the Geological Society of America and the Seismological Society of America (SSA). The title of this interview is based on his presidential address to the SSA in 1976.

Earthquake Information Bulletin (USGS)↗

Introductory remarks on NEIS from Lou Pakiser

Lou Pakiser is Chief of the Branch of Seismicity and Earth Structure of the U.S Geological Survey at Denver, Colo. He is responsible for managing the National Earthquake Information Service (NEIS), the Albuquerque Seismological Laboratory, other U.S Seismic observatories, and a reserach program related to global seismology.

Earthquake Information Bulletin (USGS)↗

Earthquakes and plate tectonics

The world's earthquakes are not randomly distributed over the Earth's surface. They tend to be concentrated in narrow zones. Why is this? And why are volcanoes and mountain ranges also found in these zones too? An explanation is to be found in plate tectonics, a concept which has revolutionized thinking in the Earth sciences in the last 10 years. The theory of plate tectonics combines many of the ideas about continental drift (originally proposed in 1912 by Alfred Wegener in Germany) and sea-floor spreading (suggested originally by Harry Hess of Princeton University).

Earthquake Information Bulletin (USGS)↗

Jupiter and the Voyager mission

In 1977, the United States launched two unmanned Voyager spacecraft that were to take part in an extensive reconnaissance of the outer planets over a 12-year period visiting the environs of Jupiter, Saturn, Uranus, and Neptune. Their first encounter was with the complex Jupiter planetary system 400 million miles away. Sweeping by Jupiter and its five moons in 1979, the two spacecraft have sent back to Earth an enormous amount of data that will prove to be vital in understanding our solar system. Voyager 1 is scheduled to fly past Saturn on November 13 of this year; Voyager 2, in August of the following year.

Earthquake Information Bulletin (USGS)↗

Seismicity and earthquake hazards of the Wasatch Front, Utah

The impressive topographic break at the base of the Wasatch Range immediately east of Salt Lake City, Utah, marks the location where Mormon colonizer Brigham Young said in 1847. "This is the place" Actually, "the place" is termed the Wasatch Front because the Wasatch Range to the east, which rises to heights of 3,600 m, fronts the valleys to the west. The densely settled Wasatch Front area has about 900,000 people, 80 percent of Utah's total population. This population is centered around Salt Lake City, a rapidly growing industrial and tourist center.

Utah↗

Records of prehistoric earthquakes in sedimentary deposits in lakes

Historic records of earthquakes are too short to allow a true assessment of their recurrence intervals. Methods are needed, therefore, that will enable the seismicity of an area to be evaluated beyond the limit of historic records. One place where a record of ancient seismic activity might be preserved is in lake sediments. Strong earthquakes often cause a phenomenon in water-saturated sediments known as liquefaction. The seismic shaking tends to reorient the sediment grains into a more compact arrangement. This usually means that the sediment liquefies and is redeposited in a smaller volume; there is an accompanying explusion of water and, in cases of severe shaking, sediment-laden water. During a strong earthquake, deformation due to liquefaction may occur in the upper layers of lake sediment. If this deformation is preserved without further deformation as new layers of sediment are deposited in the lake and if one could later find and identify these layers, one would then have a record of prehistoric earthquakes in the lake beds.

Earthquake Information Bulletin (USGS)↗

Searching for prehistoric earthquakes in lake sediments

How often do major earthquakes occur? Do they follow regular patterns of recurrence, and if so, what is the length of the recurrence interval? These questions are of obvious importance to populations located in regions where earthquakes are a commonplace occurrence. They are also relevant questions in regions that are for the most part seismically inactive but that have experienced anomalous earthquakes of destructive force one or more times in recorded history. Also, what about areas that have never experienced an earthquake in historic times? Human history is short when compared to the geologic time scale. Is it possible that places which we regard as seismically inactive might actually have experienced a major earthquake in the recent geologic past? Historic records of earthquakes are too short to allow a true assessment of recurrence intervals; therefore, a method is needed that will enable the seismic history of a region to be exteneded beyond the limit of historic time.

Earthquake Information Bulletin (USGS)↗