Smith, Stewart Wilson (1961) An investigation of the earth's free oscillations. Dissertation (Ph.D.), California Institute of Technology. http://resolver.caltech.edu/CaltechTHESIS:04132011-081816354
The free oscillations of the earth excited by the Chilean earthquake of 1960 have been measured by power spectral analysis of strain and pendulum seismographs. A revised and more precise table of free oscillation periods is presented. The period of the fundamental spheroidal mod _0S^0_2 is 53.82 minutes. Fine structure analysis has shown that for the first three spheroidal modes there is good agreement between the observed splitting and that calculated for a rotating earth. Results for the toroidal modes are uncertain. A theory is presented that allows recovery of some of the source properties from observations of phase differences for spheroidal modes. A comparison of theory with observation confirms original estimates of a fault length of 1000 km and a rupture velocity of between 3 and 4 km/sec. The effect of a moving source that decays exponentially with distance changes the pattern of phase shifts slightly but does not change estimates of the fault parameters. An alternative interpretation of the source properties in terms of the relative amplitudes of 2n + 1 split lines for each mode is presented but no calculations are performed. Preliminary data on the effects of geomagnetic storms on the oscillations of the earth place an upper limit of about 5 x 10^(16) ergs/cph for the energy density associated with the elastic coupling of several magnetic storms.
|Item Type:||Thesis (Dissertation (Ph.D.))|
|Degree Grantor:||California Institute of Technology|
|Division:||Geological and Planetary Sciences|
|Thesis Availability:||Public (worldwide access)|
|Defense Date:||1 May 1961|
|Default Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Tony Diaz|
|Deposited On:||13 Apr 2011 18:36|
|Last Modified:||26 Dec 2012 04:34|
- Final Version
See Usage Policy.
Repository Staff Only: item control page