Short-period Rayleigh-wave dispersion across the Tibetan Plateau

1975 ◽  
Vol 65 (5) ◽  
pp. 1051-1057 ◽  
Author(s):  
W. P. Chen ◽  
P. Molnar
Keyword(s):  
Tibetan Plateau ◽  
Simple Wave ◽  
Wave Dispersion ◽  
New Delhi ◽  
The Tibetan Plateau ◽  
Period Range ◽  
Short Period ◽  
Wave Forms ◽  
Wave Trains ◽  
Rayleigh Wave Dispersion

Abstract Well-dispersed Rayleigh waves within the period range of 4 to 11 sec are observed at New Delhi (NDI) and Shillong (SHL), India, for seven earthquakes near and in the Tibetan Plateau from 1963 to 1971. The dispersion curves and the simply dispersed wave forms suggest a prominent overlying wave guide, probably sediments, in the Tibetan area. The thickness of such sediments is most likely between 2.5 and 7.0 km. The simple wave trains, without much distortion due to multipathing, are consistent with a relatively inert, recent tectonism in Tibet.

Crustal structure of the Tibetan Plateau: A surface-wave study by a moving window analysis

1977 ◽  
Vol 67 (3) ◽  
pp. 735-750
Author(s):  
Kin-Yip Chun ◽  
Toshikatsu Yoshii
Keyword(s):  
Tibetan Plateau ◽  
Crustal Structure ◽  
The Tibetan Plateau ◽  
Moving Window ◽  
Low Velocity ◽  
Period Range ◽  
Window Analysis ◽  
Dispersion Data ◽  
Moving Window Analysis ◽  
Group Velocities

abstract Group velocities of fundamental-mode Rayleigh and Love waves are analyzed to construct a crustal structure of the Tibetan Plateau. A moving window analysis is employed to compute group velocities in a wide period range of 7 to 100 sec for 17 individual paths. The crustal models derived from these dispersion data indicate that under the Tibetan Plateau the total crustal thickness is about 70 km and that the crustal velocities are generally low. The low velocities are most probably caused by high temperatures. A low-velocity zone located at an intermediate depth within the crust appears to be strongly demanded by the observed dispersion data. The main features of the proposed crustal structure will place stringent constraints on future tectonic models of the Tibetan Plateau which is generally regarded as a region of active deformation due to the continent-continent collision between India and Asia.

scholarly journals Flexural–Gravity Waves on Floating Stratified Ice

1983 ◽  
Vol 29 (101) ◽  
pp. 133-141
Author(s):  
Edwin S. Robinson
Keyword(s):  
Gravity Wave ◽  
Gravity Waves ◽  
Wave Dispersion ◽  
Dispersion Curves ◽  
Homogeneous Fluid ◽  
Snow Layer ◽  
Period Range ◽  
Short Period ◽  
Flexural Gravity Waves ◽  
Flexural Gravity Wave

AbstractFlexural–gravity waves in the 3 ms to 50 ms period range were recorded on floating layers of ice ranging from 6 cm to 52 cm in thickness. These inversely dispersive waves are analogous to Rayleigh waves propagating on a multi-layered structure. Therefore, flexural–gravity wave dispersion curves can be calculated by the well-known Haskell–Thompson method. This approach allows the effects of snow layers and stratification of the ice to be evaluated. In earlier methods of calculating flexural–gravity wave dispersion. the structure was restricted to a single homogeneous solid layer over a homogeneous fluid. The effect of a low-velocity snow layer is to reduce the short-period phase velocity, and to increase the velocity at long periods. Dispersion curves for ice layers with and without a snow cover cross at an intermediate period that increases as ice thickness increases. These effects are measurable in seismic experiments on frozen ponds and lakes.

Rayleigh wave group velocities in central California

1968 ◽  
Vol 58 (3) ◽  
pp. 881-890
Author(s):  
D. J. Sutton
Keyword(s):  
Rayleigh Wave ◽  
Group Velocity ◽  
Sierra Nevada ◽  
Wave Dispersion ◽  
Wave Group ◽  
Period Range ◽  
Central California ◽  
Great Valley ◽  
Rayleigh Wave Dispersion ◽  
Group Velocities

abstract Experimentally determined Rayleigh-wave dispersion curves of group velocity are given for five paths from NTS to stations in the network operated by the Seismographic Station at U.C. Berkeley. Periods observed range from 4 to 14 seconds. Although, as expected, two different paths from NTS to the western edge of the Sierra Nevada resulted in similar curves, efforts to find empirical curves appropriate to the Great Valley and the Coast Ranges on the assumption of provinces with parallel boundaries were not successful. Estimates of group velocity across the Great Valley along the path NTS to BRK indicate velocities, in the period range 5–9 seconds, considerably lower than would be expected from crustal models so far suggested.

scholarly journals Flexural–Gravity Waves on Floating Stratified Ice

1983 ◽  
Vol 29 (101) ◽  
pp. 133-141 ◽  
Author(s):  
Edwin S. Robinson
Keyword(s):  
Gravity Wave ◽  
Gravity Waves ◽  
Wave Dispersion ◽  
Dispersion Curves ◽  
Homogeneous Fluid ◽  
Snow Layer ◽  
Period Range ◽  
Short Period ◽  
Flexural Gravity Waves ◽  
Flexural Gravity Wave

AbstractFlexural–gravity waves in the 3 ms to 50 ms period range were recorded on floating layers of ice ranging from 6 cm to 52 cm in thickness. These inversely dispersive waves are analogous to Rayleigh waves propagating on a multi-layered structure. Therefore, flexural–gravity wave dispersion curves can be calculated by the well-known Haskell–Thompson method. This approach allows the effects of snow layers and stratification of the ice to be evaluated. In earlier methods of calculating flexural–gravity wave dispersion. the structure was restricted to a single homogeneous solid layer over a homogeneous fluid. The effect of a low-velocity snow layer is to reduce the short-period phase velocity, and to increase the velocity at long periods. Dispersion curves for ice layers with and without a snow cover cross at an intermediate period that increases as ice thickness increases. These effects are measurable in seismic experiments on frozen ponds and lakes.

Seismic studies in central and eastern Tennessee

1978 ◽  
Vol 68 (4) ◽  
pp. 1081-1094
Author(s):  
E. S. Sodbinow ◽  
G. A. Bollinger
Keyword(s):  
Surface Wave ◽  
Theoretical Models ◽  
Wave Dispersion ◽  
Time Frame ◽  
Low Noise ◽  
Cumberland Plateau ◽  
Surface Wave Dispersion ◽  
Mode Dispersion ◽  
Short Period ◽  
Wave Trains

abstract Some of the seismic characteristics of Tennessee were investigated by means of a short-period surface-wave dispersion study in central Tennessee and a microearthquake survey of the eastern portion of the state. The tripartite method of phase velocity determination was applied to data from a 4-element SPZ array at the Cumberland Plateau Observatory (CPO). Seven short-period (0.5 to 1.4 sec.) surface-wave trains were analyzed. These wave trains exhibited both fundamental and first higher mode dispersion. Theoretical models, consisting of 2 or 3 layers over a half-space were developed that explain the observed dispersion. The layers, which model the surficial sediments of the region, range in total thickness from 1.6 to 2.1 km and have shear velocities from 1.70 to 3.10 km/sec. A 5-station array of portable seismographs was deployed in eastern Tennessee and 2 months of operation yielded 3000 low-noise hours of data. Eleven microearthquakes −1.3 ≦ M ≦ 1.1 were recorded during that time frame indicating that, at least for periods of several weeks, the microseismicity of eastern Tennessee can be very low.

Lateral variation of rayleigh-wave dispersion characteristics in Australia

1970 ◽  
Vol 60 (6) ◽  
pp. 1897-1906
Author(s):  
Harsh K. Gupta ◽  
Janardan G. Negi
Keyword(s):  
Rayleigh Wave ◽  
Wave Dispersion ◽  
Dispersion Characteristics ◽  
Lateral Variation ◽  
Lateral Velocity ◽  
Entire Family ◽  
Period Range ◽  
Velocity Gradients ◽  
Dispersion Data ◽  
Rayleigh Wave Dispersion

Abstract Rayleigh wave dispersion data on Australia by Bolt and Niazi (1964) and Thomas (1969) are examined in detail in the period range of 20 to 40 sec. The dispersion characteristics correspond well to region 7 in Santô's (1965) classification. A further and similar inspection of the African mass, Brazilian shield, Canadian shield etc. reveals that the entire family of shield areas systematically belongs to Santô's regions 6 and/or 7. They are uniformly characterized by the absence of appreciable lateral velocity gradients in clear contrast to corresponding extremely steep gradients for high seismicity areas.

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