Q of the Earth: Global, Regional, and Laboratory Studies

ISBN-13: 9783764360498 / Angielski / Miękka / 1999 / 498 str.

B. J. Mitchell; B. Romanowicz; Barbara Romanowicz

Opis

Variations in seismic Q are sensitive to a much greater extent than are seismic velocity variations on factors such as temperature, fluid content, and the movement of solid state defects in the earth. For that reason an understanding of Q and its variation with position in the earth and with time should provide information in earth's tectonic evolution, as well as on aspects of its internal structure. Progress in understanding Q has suffered from difficulty in obtaining reliable amplitude data at global and temporary stations. Moreover, laboratory determinations of Q, until recently, were most often made at frequencies much higher than those measured by seismologists for waves propagating through the earth. Recent advances in seismic station distribution and quality, as well as in methodology at both high and low fequencies, have greatly improved the quality of observational data available to seismologists from global stations. Concurrent advances have been made in measuring Q using laboratory samples at frequencies that pertain to the earth and in theoretical understanding of seismic wave attenuation. Papers of this volume present new information on Q in the earth from several perspectives: methodology, results from global and regional observations of both body and surface waves, laboratory measurements, and theoretical understanding. The editors believe that we have reached a new threshold in Q studies and that advances in data quality and methodology will spur increased interest in this difficult, but interesting field.

Spis treści

I: Global and Mantle Studies.- A Dislocation Model of Seismic Wave Attenuation and Micro-creep in the Earth: Harold Jeffreys and the Rheology of the Solid Earth.- Attenuation Tomography of the Earth’s Mantle: A Review of Current Status.- High-frequency P- and S-wave Attenuation in the Earth.- 2-D Image of Seismic Attenuation beneath the Deep Seismic Sounding Profile “Quartz,” Russia.- Attenuation of Broadband P and S Waves in Tonga: Observations of Frequency Dependent Q.- Three-dimensional Mapping of Magma Source and Transport Regions from Seismic Data: The Mantle Wedge beneath Northeastern Japan.- Comparison between Time-domain and Frequency-domain Measurement Techniques for Mantle Shear-wave Attenuation.- A Model to Study the Bias on Q Estimates Obtained by Applying the Rise Time Method to Earthquake Data.- II: Crustal Studies.- Seismic-frequency Laboratory Measurements of Shear Mode Viscoelasticity in Crustal Rocks II: Thermally Stressed Quartzite and Granite.- A Summary of Attenuation Measurements from Borehole Recordings of Earthquakes: The 10 Hz Transition Problem.- Frequency-dependent Attenuation of High-frequency P and S Waves in the Upper Crust in Western Nagano, Japan.- Seismic Velocity and Q Structure of the Middle Eastern Crust and Upper Mantle from Surface-wave Dispersion and Attenuation.- Seismic Attenuation Computed from GLIMPCE Reflection Data and Comparison with Refraction Results.- Lg Coda Q and its Relation to the Geology and Tectonics of the Middle East.- Lg Coda Q Variations across South America and their Relation to Crustal Evolution.- Regional Variation of Lg Coda Q in the Continental United States and its Relation to Crustal Structure and Evolution.- Lg Coda Q in Australia and its Relation to Crustal Structure and Evolution.- Lg Coda Q and its Relation to the Structure and Evolution of Continents: A Global Perspective.- Comparison of Seismic Body Wave and Coda Wave Measures of Q.- Estimation of the Intrinsic Absorption and Scattering Attenuation in Northeastern Venezuela (Southeastern Caribbean) Using Coda Waves.- Intrinsic and Scattering Seismic Attenuation in W. Greece.- Coda Q Estimates in the Koyna Region, India.