Universal dispersion tables

1969 ◽  
Vol 59 (4) ◽  
pp. 1667-1693
Author(s):  
Don L. Anderson ◽  
Robert L. Kovach
Keyword(s):  
Upper Mantle ◽  
Free Oscillation ◽  
Velocity Structure ◽  
Shear Velocity ◽  
Average Density ◽  
Earth Model ◽  
The Core ◽  
The Earth ◽  
Small Change ◽  
Dominant Parameter

Abstract The effect of a small change in any parameter of a realistic Earth model on the periods of free oscillation is computed for both spheroidal and torsional modes. The normalized partial derivatives, or variational parameters, are given as a function of order number and depth in the Earth. For a given mode it can immediately be seen which parameters and which regions of the Earth are controlling the period of free oscillation. Except for oSo and its overtones the low-order free oscillations are relatively insensitive to properties of the core. The shear velocity of the mantle is the dominant parameter controlling the periods of free oscillation and density can be determined from free oscillation data only if the shear velocity is known very accurately. Once the velocity structure is well known free oscillation data can be used to modify the average density of the upper mantle. The mass and moment of inertia are then the main constraints on how the mass must be redistributed in the lower mantle and core.

INVESTIGATING S VELOCITY STRUCTURE OF THE UPPER MANTLE BENEATH WEST INDONESIA USING SEISMOGRAM ANALYSIS OF TWO STRONG SOUTH JAVA EARTHQUAKES IN MALAYSIAN SEISMOLOGICAL NETWORK

2010 ◽  
Vol 04 (04) ◽  
pp. 321-339
Author(s):  
BAGUS JAYA SANTOSA
Keyword(s):  
Upper Mantle ◽  
Velocity Structure ◽  
Corner Frequency ◽  
Earth Model ◽  
Time Data ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Arrival Times ◽  
The Earth ◽  
Seismological Network

This research investigated the S speed structure in the upper mantle beneath West Indonesia by analyzing the seismogram triggered by the C052606A and C071706B earthquakes in South Java and recorded at the Malaysian seismological network MY. The method used is waveform comparison between the measured seismogram and the synthetic one in the time domain and three Cartesian components simultaneously, instead of travel time data or dispersion curve, which are commonly used by other seismologists. The seismogram comparison was conducted in the same unit and a low-pass filter with 20 mHz corner frequency was applied to both seismograms. Seismogram analysis shows very strong deviations in the arrival times and amplitudes of the Love and Rayleigh surface waveforms. To solve the observed deviation, a correction on the earth structure covering the speed gradient of βh and the value of zero-order coefficients for the βh and βv in the earth upper mantle is required. The research's result shows that the area of East Sumatra and Borneo has negative correction of S speed structure in the upper mantle layers, compared to PREMAN standard earth model. This result is different from other seismological result.

scholarly journals Mantle Rayleigh waves from the Kamchatka earthquake of November 4, 1952*

1954 ◽  
Vol 44 (3) ◽  
pp. 471-479
Author(s):  
Maurice Ewing ◽  
Frank Press
Keyword(s):  
Internal Friction ◽  
Rayleigh Waves ◽  
Shear Velocity ◽  
Velocity Curve ◽  
The Core ◽  
Long Period ◽  
A Value ◽  
The Earth ◽  
Dispersion Data ◽  
Kamchatka Earthquake

Abstract Mantle Rayleigh waves from the Kamchatka earthquake of November 4, 1952, are analyzed. The new Palisades long-period vertical seismograph recorded orders R6–R15, the corresponding paths involving up to seven complete passages around the earth. The dispersion data for periods below 400 sec. are in excellent agreement with earlier results and can be explained in terms of the known increase of shear velocity with depth in the mantle. Data for periods 400-480 sec. indicate a tendency for the group velocity curve to level off, suggesting that these long waves are influenced by a low or vanishing shear velocity in the core. Deduction of internal friction in the mantle from wave absorption gives a value 1/Q = 370 × 10−5 for periods 250-350 sec. This is a little over half the value reported earlier for periods 140-215 sec.

The Earth’s Free Spherical Oscillations of the Great Japan Earthquake

2012 ◽  
Vol 622-623 ◽  
pp. 1664-1669 ◽  
Author(s):  
Ye Wu ◽  
Yong Ge Wan ◽  
Liang Ding
Keyword(s):  
Free Oscillation ◽  
Low Frequency ◽  
Earth Model ◽  
Frequency Signal ◽  
The Earth ◽  
Oscillation Modes ◽  
Spectral Splitting ◽  
Earth’S Free Oscillations ◽  
Earth’S Free Oscillation ◽  
Digital Seismic Network

An M9.0 earthquake struck Japan on March 11, 2011 and the strong earthquake made continuous oscillation of the Earth. We first studied the Earth’s free oscillations using observations of VHZ channel of China Digital Seismic Network (CDSN). Since the frequency response of seismograph in CDSN suppresses the information of low frequency signal, we do not need to remove the solid tide in our data processing. We extracted 72 clear spherical modes of (0S0,0S2to0S72) of the Earth’s free oscillation and 21 harmonic modes and they are consistent and nearly same with the frequencies of the modes of Preliminary Reference Earth Model (PREM). Spectral splitting phenomenon is observed obviously in0S2,0S3,0S4and1S2free oscillation modes.

The Earth’s Free Spherical Oscillations of the Chile Earthquake

2012 ◽  
Vol 622-623 ◽  
pp. 1674-1681
Author(s):  
Ye Wu ◽  
Shu Yang ◽  
Liang Ding
Keyword(s):  
Free Oscillation ◽  
Low Frequency ◽  
Earth Model ◽  
The Earth ◽  
Oscillation Modes ◽  
Chile Earthquake ◽  
Spectral Splitting ◽  
Earth’S Free Oscillations ◽  
Earth’S Free Oscillation ◽  
Digital Seismic Network

An M8.8 earthquake struck Chile on February 27, 2010 and the strong earthquake made continuous oscillation of the Earth. We studied the Earth’s free oscillations using observations of VHZ channel of China Digital Seismic Network (CDSN). Since the frequency response of seismograph in CDSN suppresses the information of low frequency signal, we do not need to remove the solid tide in our data processing. We extracted 76 clear spherical modes of (0S0, 0S2 to 0S76) of the Earth’s free oscillation and 78 harmonic modes and they are consistent and nearly same with the frequencies of the modes of Preliminary Reference Earth Model (PREM). Spectral splitting phenomenon is observed obviously in 0S2, 0S3, 0S4 and 1S2 free oscillation modes.

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