Journal of Physics of the Earth
Online ISSN : 1884-2305
Print ISSN : 0022-3743
ISSN-L : 0022-3743
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Volume 36, Issue 5
Displaying 1-4 of 4 articles from this issue
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  • ON THE DERIVATION OF THE ELASTIC EQUATION OF MOTION
    Robert J. GELLER
    1988 Volume 36 Issue 5 Pages 201-228
    Published: 1988
    Released on J-STAGE: April 30, 2009
    DOIhttps://doi.org/10.4294/jpe1952.36.201
    JOURNAL FREE ACCESS
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    Several key points in elastodynamics are reexamined. The variational principle is the most fundamental axiom of classical mechanics; for a point particle originally at r, the virtual displacement r→r+δu leads to Newton's second law, f=ma. On the other hand, elastodynamics considers a continuum that has already been subjected to a displacement u before the virtual displacement r+u→r+u+δu. The present paper shows that because of this difference in the nature of the virtual displacement, the variational principle for continua does not in general lead to Newton's second law. The present paper also shows that the generalized form of Hooke's Law with 36 independent elastic constants always leads to the existence of a strain energy function, because, as a consequence of elementary results in linear algebra, the strain energy due to the 15 antisymmetric components of the elastic tensor is identically zero.
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  • A SIMPLE METHOD TO CALCULATE SYNTHETIC LONG-PERIOD SEISMOGRAMS INCORPORATING FIRST-ORDER ASYMPTOTICS
    Eiji MOCHIZUKI
    1988 Volume 36 Issue 5 Pages 229-236
    Published: 1988
    Released on J-STAGE: April 30, 2009
    DOIhttps://doi.org/10.4294/jpe1952.36.229
    JOURNAL FREE ACCESS
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    A simple method is suggested to calculate synthetic long-period seismograms by normal mode summation. Effects of the lateral heterogeneity are incorporated by the first-order asymptotics which are valid up to the order of l-1 (l: angular order). Synthetic seismograms of a laterally heterogeneous earth model can be calculated by those of a spherically symmetric earth model with varying frequency, epicentral distance, amplitude, and azimuth.
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  • UPPER CRUSTAL STRUCTURE AROUND KAMAFUSA DAM, MIYAGI PREFECTURE, JAPAN, USING A LARGE AIRGUN ON LAND
    Azusa NISHIZAWA, Tadayasu SAIJO, Kiyoshi SUYEHIRO, Akiko HASEMI, Taku ...
    1988 Volume 36 Issue 5 Pages 237-248
    Published: 1988
    Released on J-STAGE: April 30, 2009
    DOIhttps://doi.org/10.4294/jpe1952.36.237
    JOURNAL FREE ACCESS
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    Seismic refraction profiles using a large airgun on land were shot at the Kamafusa Dam area, Miyagi Prefecture, Japan, in 1985. Data from two 13-km-long airgun profiles and a quarry explosion profile were processed through stacking and filtering. A two-dimensional ray tracing method was applied to explain the data. The obtained upper crustal structure is composed of three layers with P-wavespeeds of about 2.6-3.0, 4.0-4.2, and 5.5 km/s. The configuration of the interface between the upper two layers is similar to the basement depth deduced from the published gravity data.
    We also observed the same airgun data at several telemeter network stations and could record the signals transmitted over 60 km. This experiment demonstrated the feasibility and effectiveness of using an airgun on land in upper crustal structure investigation.
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  • ON THE STATIC DEFORMATION OF THE EARTH
    Eiji MOCHIZUKI
    1988 Volume 36 Issue 5 Pages 249-253
    Published: 1988
    Released on J-STAGE: April 30, 2009
    DOIhttps://doi.org/10.4294/jpe1952.36.249
    JOURNAL FREE ACCESS
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