abstract

Recent theoretical results show that, in addition to P and S pulses, two pulse-like phenomena, denoted by

P
and
S
, can be defined near the boundary of an elastic solid. The
S
pulse is the classic Rayleigh pulse in Lamb's problem and is the classic Stoneley pulse in Cagniard's problem. When the Stoneley existence conditions are violated, the
S
pulse still exists for many solid pairs and can be regarded as a radiating interface pulse. The
P
pulse is distinct only when σ (Poisson's ratio) is greater than about 0.4. It seems to be the dual to the
S
pulse. It is the classic Stoneley pulse in Strick's problem. The
P
pulse has been observed by Kisslinger in loess and clay near Florrisant, Missouri. The radiating
S
pulse has been observed by Pod''yapol'ski and Vassil'ev on a clay/granite interface, and by Roever and Vining on a fluid/solid interface. Roever and Vining may also have observed the
P
pulse on pitch. Two dimensional seismic model studies of the
S
pulse suggest that it is most easily recognized from its particle orbit. Model results for both the trapped and the radiating
S
pulse agree well with theoretical calculations of orbital motion and orbital tilt. The tilt of the
P
orbit in Lamb's problem is virtually independent of the elastic parameters and the
P
velocity is very nearly twice the S velocity. In dispersion problems both radiating
P
and
S
pulses appear as kinks in the dispersion curves.

First Page Preview

First page PDF preview
You do not currently have access to this article.