Near Source Contributions to Teleseismic P Wave Coda and Regional Phases.

摘要

This report presents the results of an investigation of near-source effects on teleseismic P-wave and early P-wave coda spectra for underground explosions. The underlying objective of this research has been to determine whether the differential behavior of P and P coda can be exploited to remotely determine near-source properties such as overburden velocity, burial depth, and degree of saturation. The report also contains a review paper on the pP phase, focussed on assessing the various methodologies that have been used to determine pP parameters and trying to reconcile the existing discrepancies in various estimates. The final section of the report is an encyclopedia article on the role of seismological monitoring of nuclear testing treaties. Energy radiated upward from underground nuclear explosions has a complex interaction with the free surface that strongly influences the seismic wavefields recorded at teleseismic and regional distances. This interaction, differing from that for earthquakes primarily due to the much higher strains and strain rates involved, is essential to understand for both explosion yield estimation and event discrimination. Reflection of explosion P wave energy from the free surface, which produces the pP phase, involves frequency-dependent, non-linear processes that are intimately linked to surface spallation.