Open AccessBody‐Force Equivalent Calculations from Permanent Deformation in the Near Field
Author(s) -
Nyland E.
Publication year - 1973
Publication title -
geophysical journal of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.302
H-Index - 168
eISSN - 1365-246X
pISSN - 0016-8009
DOI - 10.1111/j.1365-246x.1973.tb05832.x
Subject(s) - deformation (meteorology) , geology , body force , creep , stress (linguistics) , relaxation (psychology) , stress field , field (mathematics) , seismology , geophysics , physics , classical mechanics , mathematics , finite element method , psychology , social psychology , linguistics , oceanography , philosophy , thermodynamics , pure mathematics
Summary The body‐force equivalents that reproduce the permanent deformation around seismic events need not coincide with those deduced from dynamic properties of the radiation. The differences can be ascribed to creep‐like phenomena and the relaxation of a regional stress pattern. Solutions for the body‐force equivalents around both the Dixie Valley earthquakes of Nevada and the Faultless explosion event yield an unambiguous indication of a single‐couple body‐force equivalent. Although the data are not as clear, a solution of the Tango earthquake in Japan suggests the possibility of a deep‐seated monopole source of uplift. The distribution of body‐force equivalent for near‐field deformation can be used as a guide to the behaviour of blocks of formations in the near field. This is demonstrated in the solution of the Dixie Valley earthquakes in Nevada. Quasi‐static phenomena such as the permanent deformation in the near field can be modelled by sources which have a net moment in the vicinity of the focal volume. This does not mean that the net mechanism associated with quasi‐static phenomena has net moment. In order to conserve angular momentum in the Earth, it is necessary for adjustments to occur at considerable distances from the source.