The Teleseismic Manifestation of pP: Problems and Paradoxes
- Steven R. Taylor,
- Howard J. Patton and
- Paul G. Richards
Published Online: 18 MAR 2013
Copyright 1991 by the American Geophysical Union.
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
- Published Online: 18 MAR 2013
- Published Print: 1 JAN 1991
Print ISBN: 9780875900315
Online ISBN: 9781118663820
- Underground nuclear explosions—Detection—Congresses;
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.