Physical and mathematical arguments are presented for equipartition as the statistical state achieved by a ran- dom field, independent of its sources, in the limit of enough scattering. The arguments are simplest for ...Physical and mathematical arguments are presented for equipartition as the statistical state achieved by a ran- dom field, independent of its sources, in the limit of enough scattering. The arguments are simplest for the case of thermally excited fields, but are shown to apply also, with caveats, in non-equilibrium acoustics and seismology. Practical implications are discussed.展开更多
Seismic coda wave is the tail portion of the earthquake record after main arrivals.Studies on the coda usually focus on high-frequency data within several hours after regional events and attribute them to the scatteri...Seismic coda wave is the tail portion of the earthquake record after main arrivals.Studies on the coda usually focus on high-frequency data within several hours after regional events and attribute them to the scattering effect of the heterogeneities inside the earth.Here,we use records of seven large earthquakes at globally distributed seismic stations to examine the decay of long-period(100 s to 300 s)coda in the time window of 10,000 s to 140,000 s after the origin time and fit it with a statistical model.The geometric spreading effect in the estimated initial energy and a locationindependent equivalent attenuation coefficient indicate that the long-period coda energy is less affected by the heterogeneity-induced scattering effect than that of shorterperiod coda.The coda energy can reach the earth’s inner core and can be explained by a 1D earth model,making it more effective for constraining the global attenuation model.It also has the potential to determine the magnitudes of large earthquakes and to explore the interior of planetary bodies.展开更多
文摘Physical and mathematical arguments are presented for equipartition as the statistical state achieved by a ran- dom field, independent of its sources, in the limit of enough scattering. The arguments are simplest for the case of thermally excited fields, but are shown to apply also, with caveats, in non-equilibrium acoustics and seismology. Practical implications are discussed.
基金the National Natural Science Foundation of China(No.U1939204).
文摘Seismic coda wave is the tail portion of the earthquake record after main arrivals.Studies on the coda usually focus on high-frequency data within several hours after regional events and attribute them to the scattering effect of the heterogeneities inside the earth.Here,we use records of seven large earthquakes at globally distributed seismic stations to examine the decay of long-period(100 s to 300 s)coda in the time window of 10,000 s to 140,000 s after the origin time and fit it with a statistical model.The geometric spreading effect in the estimated initial energy and a locationindependent equivalent attenuation coefficient indicate that the long-period coda energy is less affected by the heterogeneity-induced scattering effect than that of shorterperiod coda.The coda energy can reach the earth’s inner core and can be explained by a 1D earth model,making it more effective for constraining the global attenuation model.It also has the potential to determine the magnitudes of large earthquakes and to explore the interior of planetary bodies.
