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The destructive force of earthquakes has stimulated human inquiry since ancient times, yet the scientific study of earthquakes is a surprisingly recent endeavor. Instrumental recordings of earthquakes were not made until the second half of the 19th century, and the primary mechanism for generating seismic waves was not identified until the beginning of the 20th century. From this recent start, a range of laboratory, field, and theoretical investigations have developed into a vigorous new discipline: the science of earthquakes. As a basic science, it provides a comprehensive understanding of earthquake behavior and related phenomena in the Earth and other terrestrial planets. As an applied science, it provides a knowledge base of great practical value for a global society whose infrastructure is built on the Earth's active crust. This book describes the growth and origins of earthquake science and identifies research and data collection efforts that will strengthen the scientific and social contributions of this exciting new discipline.
Organized by theme, this comprehensive encyclopedia examines all aspects of life in Japan, from geography and government to food and etiquette and much more. Japan, or the "Land of the Rising Sun," is home to more than 126 million people, nearly 10 million of whom live in Tokyo alone. How did this tiny island nation become such a powerhouse in the 21st century, and where will it go from here? Modern Japan examines history and contemporary life through thematic entries organized into chapters covering such topics as geography; history; government and politics; economy; religion and thought; social classes and ethnicity; gender, marriage, and sexuality; education; language; etiquette; literature and drama; art and architecture; music and dance; food; leisure and sports; and media and popular culture. Each chapter contains an overview of the topic and alphabetized entries on examples of each theme. A chronology covers from prehistoric times to the present, and special appendices offer profiles of a typical day in the life of representative members of Japanese society, key facts and figures about Japan, and a holiday chart. This volume is ideal for students researching Japan, as well as general readers interested in learning more about the country.
The report summarizes one year of theoretical and applied research on propagation of seismic waves and techniques for analyzing data. The main objectives were to determine the frequency and energy of seismic signatures, and investigate attenuation, patterns of azimuthal radiation from source regions, and methods of determining the type of motion at the source. Natural and artificial sources were studied to develop diagnostic aids for distinguishing between earthquakes and underground nuclear detonations. Equipment for selection, reformatting, and digital-to-analog conversion for digitally recorded LASA data was constructed and is being checked out. Several approaches for using the parallel computational capabilities of optics for LASA data were developed. A study of background noise and reciprocity for teleseismic events as recorded on the bottom of a large fresh water lake has commenced with the emplacement of three-component seismometers in Lake Superior. Array data have been used for crustal studies on the Eastern United States. Digital mode filtering was investigated. A perturbation theory for seismic sources was developed. (Author).
This report presents the results of a study of the coupling of seismic energy to the SOFAR channel and the propagation of acoustic energy from source to receiver. The results of an investigation of T-phase amplitude level vs. earthquake magnitude are presented for events in the Pacific ocean. The poor correlation between these parameters suggests that the generation of detectable T-phases is dependent not only upon event magnitude and depth, source mechanism, and transmission loss from source to receiver, but also on details of the source bathymetry which govern the coupling of seismic to acoustic energy. Despite the complexities of the data, several features of T-phase data that are readily observable are: (1) T-phase energy for submarine earthquakes drops off rapidly at frequencies greater than 16 Hz, and (2) that the nature of the T-phase coda is strongly dependent on the geographic source area, thus T-phases from the same area tend to be very similar.
Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.
An ocean bottom seismograph was deployed on the seaward side of the Kuril Trench off Hokkaido, Japan, in 5460 m of water, in August 1975 during the joint Soviet-American Tsunami Expedition. During the seven-day record, S-P times were distributed in three groups: 19-24 sec, corresponding to aftershocks of the 10 June and 13 June 1975 earthquakes southeast of Nemuro, Japan and to earthquakes east of Sanriku, Japan; approximately 30 sec, from south of Erimo Peninsula, Hokkaido; and approximately 100 sec, from the Izu-Bonin Islands. Seven earthquakes, with hypocenters well determined by the land seismic net, are studied in detail. A shallow focus earthquake yields typical oceanic mantle velocities shallower than 50 km in the slab which dips under the Japanese archipelago. However, deeper focus earthquakes reveal anomalously high velocities averaged over the upper 230 km, in agreement with the models of Utsu and Oliver and Isacks. Two deep earthquakes, whose paths lie in the Pacific Ocean asthenosphere, suggest a velocity 3% lower than that predicted by Jeffreys-Bullen, in agreement with the above models. Spectral analysis of S arrivals suggests Q sub s values of 1000-1500 for nearby earthquakes and 4000-6000 for longer-distance earthquakes, implying an unusual attenuation mechanism for long travel paths, which enhances the high frequencies.
The 1970s and 1980s have been marked by turbulent times for certain portions of America's industrial base, as their dominance of many do mestic and foreign markets has eroded. During such times of stress it is tempting to create scapegoats in order to rationalize shortcomings. Much is heard about the Japanese in this regard. How they have contributed to the deterioration of specific segments of American indus try, how jobs in the U. S. are being lost to foreign competition, and how the resulting trade deficit will be the downfall of us all. Much of this rhetoric has been directed against the Japanese automobile manu facturers and the Japanese electronic industry, which has been accused of "dumping" product into the United States. It was not until Japan unveiled its plan to build the multi-billion dollar Kansai Airport project that Japanese restrictive bidding practices in their domestic construction market became headline news. Construc tion then became a popular subject for "Japan Bashing" and attention was focused on the activities of Japanese contractors around the world, and, more particularly, on their involvement in the U. S. construction market. Well, the Japanese construction companies are in the United States and have been for some time. They have been awarded many contracts for federal and municipal construction projects and they have negotiated a significant number of construction contracts in the private sector.
Reprint from Pure and Applied Geophysics (PAGEOPH), Volume 135 (1991), No. 2