Seismological Research in Singapore     

Mah King Kheong  Lim Lay Eng 《中国地震研究》2002,16(3):243-252

The Singapore seimic network and the seismicity of Singapore are briefly described,the four tremor events experienced by Singapore are discussed and the ground responses of different stations are compared,The tremor incident standing operation procedure is also prsented.  相似文献   

The velocity structure of the crust and upper mantle under China from broad-band P and PP waveform analysis   总被引：3，自引：0，他引：3  

Jos Beckers  Susan Y. Schwartz  Thorne Lay 《Geophysical Journal International》1994,119(2):574-594

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Observations of teleseismicP wave coda for underground explosions     

Christopher S. Lynnes  Thorne Lay 《Pure and Applied Geophysics》1988,128(1-2):231-249

The earlyP wave coda (5–15 sec after the first arrival) of underground explosions at the Nevada Test Site is studied in the time domain using 2082 teleseismic short-period recordings, with the intent of identifying near-source contributions to the signals in the frequency range 0.2–2.0 Hz. Smaller magnitude events tend to have relatively high coda levels in the 0.4–0.8 Hz frequency band for both Yucca Flat and Pahute Mesa explosions. Coda complexity in this low-frequency passband is negatively correlated with burial depth for Pahute Mesa events but is only weakly correlated with depth for Yucca Flat events. Enhanced excitation of relatively long-period scattered waves for smaller, less deeply buried events is required to explain this behavior. Coda complexity in the 0.8–1.1 Hz band is positively correlated with magnitude and depth for Pahute Mesa events, but has no such dependence for Yucca Flat events. This may result from systematic variations between the spectra of direct signals and coda arrivals caused bypP interference for the largest events, all of which were detonated at Pahute Mesa. Another possible explanation is a frequency-dependent propagation effect on the direct signals of the larger events, most of which were located in the center of the mesa overlying strong lateral velocity gradients in the crust and upper mantle. Event average complexity varies spatially for both test sites, particularly in the 0.8–1.1 Hz band, providing evidence for frequency-dependent focussing or scattering by near-source structure. Both the direct arrivals and the early coda have strong azimuthal amplitude patterns that are produced by defocussing by mantle heterogeneity. The direct arrivals have stronger coherent azimuthal patterns than the early coda for Pahute Mesa events, indicating more pronounced deep crustal and shallow mantle defocussing for the direct signals. However, for Yucca Flat events the direct arrivals have less coherent azimuthal patterns than the coda, suggesting that a highly variable component of near-source scattering preferentially affecting the downgoing energy is superimposed on a pattern produced by mantle heterogeneity that affects the entire signal. This complicated behavior of the direct arrivals may be the result of triplications and caustics produced by the complex basement structure known to underlie the Yucca Flat test site. The presence of strong azimuthal patterns in the early coda indicates that source strength estimates based on early coda are subject to biases similar to those affecting estimates based on direct arrivals.  相似文献   

Quantitative analysis of land surface topography   总被引：8，自引：0，他引：8  

Lyle W. Zevenbergen  Colin R. Thorne 《地球表面变化过程与地形》1987,12(1):47-56

Land surface topography significantly affects the processes of runoff and erosion. A system which determines slope, aspect, and curvature in both the down-slope and across-slope directions is developed for an altitude matrix. Also, the upslope drainage area and maximum drainage distance are determined for every point within the altitude matrix. A FORTRAN 66 program performs the analysis.  相似文献   

Diesel degradation in soil catalyzed by the addition of a bioagent     

Y. Lin  J.-J. Lay  W. K. Shieh 《International Journal of Environmental Science and Technology》2016,13(2):551-560

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Analysis of riverbank instability due to toe scour and lateral erosion     

Colin R. Thorne  Steven R. Abt 《地球表面变化过程与地形》1993,18(9):835-843

This paper provides instruction in the use of the computer spreadsheet to undertake the calculations necessary to apply the Osman–Thorne bank stability analysis for steep, eroding riverbanks. The guide explains how to input the necessary parameters into the LOTUS 123 spreadsheet in order to:

• 1 find the initial factor of safety of the bank with respect to slab-type failure;
• 2 test the sensitivity of bank stability to changes in the engineering properties of the bank material;
• 3 analyse the response of bank stability to toe scour and/or lateral erosion and find the critical condition;
• 4 find the geometry of the failure surface and failure block;
• 5 analyse the response of bank stability to further toe scour and/or lateral erosion;
• 6 find the geometry of the failure surface and failure block in subsequent failures.

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The magnetospheric reflection of whistlers     

L. R. Lyons  R. M. Thorne 《Planetary and Space Science》1970,18(12):1753-1767

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Time-domain Pure-state Polarization Analysis of Surface Waves Traversing California     

J.?Zhang  W. R.?Walter  T.?Lay  R.-S.?Wu 《Pure and Applied Geophysics》2003,160(8):1447-1478

-- A time-domain pure-state polarization analysis method is used to characterize surface waves traversing California parallel to the plate boundary. The method is applied to data recorded at four broadband stations in California from twenty-six large, shallow earthquakes which occurred since 1988, yielding polarization parameters such as the ellipticity, Euler angles, instantaneous periods, and wave incident azimuths. The earthquakes are located along the circum-Pacific margin and the ray paths cluster into two groups, with great-circle paths connecting stations MHC and PAS or CMB and GSC. The first path (MHC-PAS) is in the vicinity of the San Andreas Fault System (SAFS), and the second (CMB-GSC) traverses the Sierra Nevada Batholith parallel to and east of the SAFS. Both Rayleigh and Love wave data show refractions due to lateral velocity heterogeneities under the path, indicating that accurate phase velocity and attenuation analysis requires array measurements. T he Rayleigh waves are strongly affected by low velocity anomalies beneath Central California, with ray paths bending eastward as waves travel toward the south, while Love waves are less affected, providing observables to constrain the depth extent of anomalies. Strong lateral gradients in the lithospheric structure between the continent and the ocean are the likely cause of the path deflections.  相似文献   

Crustal thickness,VP/VS ratio,and shear wave velocity structures beneath Myanmar and their tectonic implications     

Lay Nwe  Zigen Wei  Zhiwei Li  Feng Bao  Xuelei Li  Jintao Hu 《地震研究进展（英文）》2022,2(1):100060

The crustal structure in Myanmar can provide valuable information for the eastern margin of the ongoing Indo-Eurasian collision system. We successively performed H–k stacking of the receiver function and joint inversion of the receiver function and surface wave dispersion to invert the crustal thickness (H), shear wave velocity (V_S), and the V_P/V_S ratio (k) beneath nine permanent seismic stations in Myanmar. H was found to increase from 26 ?km in the south and east of the study area to 51 ?km in the north and west, and the V_P/V_S ratio was complex and high. Striking differences in the crust were observed for different tectonic areas. In the Indo-Burma Range, the thick crust (H ?～ ?51 ?km) and lower velocities may be related to the accretionary wedge from the Indian Plate. In the Central Myanmar Basin, the thin crust (H ?= ?26.9–35.5 ?km) and complex V_P/V_S ratio and V_S suggest extensional tectonics. In the Eastern Shan Plateau, the relatively thick crust and normal V_P/V_S ratio are consistent with its location along the western edge of the rigid Sunda Block.  相似文献   

Transport properties of the lower mantle     

Kei Hirose  Thorne Lay  David Yuen 《Physics of the Earth and Planetary Interiors》2010,180(3-4):109-110

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