Go to  Advanced Search

Radiation from tensile fractures.

Show full item record

Files in this item

Files Size Format Description   View
UBC_1963_A1 M25 R2.pdf 4.937Mb Adobe Portable Document Format   View/Open
Title: Radiation from tensile fractures.
Author: Mansinha, Lalatendu
Degree Doctor of Philosophy - PhD
Program Physics
Copyright Date: 1962
Subject Keywords Strains and stresses
Abstract: The geographical distribution of the sense of the first motion of P waves (and to a very limited extent, S waves) has been studied by seismologists to provide information on the focal mechanism of earthquakes. In this thesis we investigate the inverse problem; knowing the type and form of displacement at the focus at the focal instant, we study the azimuthal distribution of the sense of first P and S motion, using model seismic technique. The source of elastic energy is a thermally induced tensile fracture in a glass plate. Two types of fractures have been studied: Initial (Bilaterally propagating) Fractures and Extended (Unilaterally propagating) Fractures. The azimuthal distribution of the P and S wave amplitudes is indicated. The experiments reported in this thesis constitute a partial test of a recent theory by Knopoff and Gilbert (1960) on first motions from seismic sources. The type of fracture studied corresponds to Case 3 of Knopoff and Gilbert. Our results show significant discrepancies with the theory. The sense of the measured first S motion is opposite to that predicted by the theory, for both Initial and Extended Fractures. The ratios Pө /P₉₀ and Sө/Pө differ in magnitude from the theory in many azimuths. It is suggested that the discrepancies are possibly due to the neglect in the theory of non-linear elastic effects near the tip of the fracture.
URI: http://hdl.handle.net/2429/38872
Series/Report no. UBC Retrospective Theses Digitization Project [http://www.library.ubc.ca/archives/retro_theses/]
Scholarly Level: Graduate

This item appears in the following Collection(s)

Show full item record

All items in cIRcle are protected by copyright, with all rights reserved.

UBC Library
1961 East Mall
Vancouver, B.C.
Canada V6T 1Z1
Tel: 604-822-6375
Fax: 604-822-3893