The Teleseismic Manifestation of pP: Problems and Paradoxes

  1. Steven R. Taylor,
  2. Howard J. Patton and
  3. Paul G. Richards
  1. Thorne Lay

Published Online: 18 MAR 2013

DOI: 10.1029/GM065p0109

Explosion Source Phenomenology

Explosion Source Phenomenology

How to Cite

Lay, T. (1991) The Teleseismic Manifestation of pP: Problems and Paradoxes, in Explosion Source Phenomenology (eds S. R. Taylor, H. J. Patton and P. G. Richards), American Geophysical Union, Washington, D. C.. doi: 10.1029/GM065p0109

Author Information

  1. Institute of Tectonics and C. F. Richter Seismological Laboratory, University of California, Santa Cruz, California 95064

Publication History

  1. Published Online: 18 MAR 2013
  2. Published Print: 1 JAN 1991

ISBN Information

Print ISBN: 9780875900315

Online ISBN: 9781118663820

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Keywords:

  • Underground nuclear explosions—Detection—Congresses;
  • Seismology—Congresses

Summary

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 for discriminating earthquakes from explosions. 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. Attempts to characterize the teleseismic pP arrival using a variety of time series analysis procedures have yielded seemingly inconsistent results, which can be attributed to a combination of limited bandwidth, neglected frequency dependence, and unresolved trade-offs with source time function, receiver and attenuation effects. Recovery of broadband ground displacement, now viable with modern instrumentation, is resulting in more robust characterizations of the pP and spallation arrivals; however, the intrinsic trade-offs with source parameters and attenuation remain. Numerical procedures to account for the non-linear interactions, surface topographic effects, and shallow crustal heterogeneity are enabling a more complete modeling of the free surface interaction.