Prospective Cohort Study


 The spectral ratio between horizontal and vertical components (H/V ratio) of microtremors measured at the ground surface has been used to estimate fundamental periods and amplification factors of a site, although this technique lacks theoretical background. The aim of this article is to formulate the H/V technique in terms of the characteristics of Rayleigh and Love waves, and to contribute to improve the technique. The improvement includes use of not only peaks but also troughs in the H/V ratio for reliable estimation of the period and use of a newly proposed smoothing function for better estimation of the amplification factor. The formulation leads to a simple formula for the amplification factor expressed with the H/V ratio. With microtremor data measured at 546 junior high schools in 23 wards of Tokyo, the improved technique is applied to mapping site periods and amplification factors in the area.

Ground Motion Characteristics Estimated from Spectral Ratio between Horizontal and Verticcl Components of Mietremors.

Interpretation theory in applied geophysics: Grant, F S ... Interpretation theory in applied geophysics Unknown Binding – January 1, 1965 5.0 out of 5 stars 1 rating. See all formats and editions Hide other formats and editions. The Amazon Book Review Book recommendations, author interviews, editors' picks, and more. Read it now. Enter your mobile number or email address below and we'll send you a ...

Interpretation Theory in Applied Geophysics Grant (McGraw-Hill, 140s.)

Lunar sourcebook. A user's guide to the moon

Ground penetrating radar (GPR) is a tool for indirectly looking at underground objects (such as graves), gravel and sand layers, and other underground structures. The information or data received by GPR is like an x-ray or map of the underground. In fact, GPR uses electromagnetic (EM) waves, as xray machines do, but GPR uses radio waves, which have a longer wavelength (see Figure A1). The wavelength, or the length of one wave, is the fundamental difference between the forms of electromagnetic energy. For example, the wavelength of x-rays range from about 10 billionths of a meter to about 10 trillionths of a meter, whereas radio waves can be a few meters long.

Ground Penetrating Radar

Stratigraphy of the Von Kármán Crater Based on Chang'E-4 Lunar Penetrating Radar Data

Lunar-penetrating radar (LPR) was conducted by the “Yutu” rover of China's Chang-E 3 lunar mission to study the shallow subsurface of the Moon Both regolith modeling and numerical simulation can provide a reliable reference for data processing of the Moon In this study, a 3-D lunar regolith model that considered some key factors including terrain, rocks, randomness of medium, and permittivity change with depth is built Based on LPR numerical simulation, v(z) f-k migration, with high accuracy for vertical velocity variations, is carried out Compared with Stolt f-k migration, which is limited to constant velocity, v(z) f-k migration performs better We have designed a workflow for LPR data of Chang-E 3 mission, such as v(z) f-k migration, filters, and gain Finally, according to the LPR real data result, we estimate the thickness of the regolith, the location and physical parameters of several rocks, and randomness of medium Besides, the present study provides a good reference for further understanding of lunar near-surface geological information

Simulation of the Lunar Regolith and Lunar-Penetrating Radar Data Processing

We present a skeletonized inversion method that inverts sur face-wave data for the Q s quality factor. Similar to the inversion of dispersion curves for th e S-wave velocity model, the complicated surface-wave arrivals are skeletonized as simple r data, namely the amplitude spectra of the windowed Rayleigh-wave arrivals . The optimalQs model is the one that minimizes the difference in the peak frequencies of the predicted and o bserved Rayleigh wave arrivals using a gradient-based wave-equation optimization method . S lutions to the viscoelastic waveequation are used to compute the predicted Rayleigh-wave ar ri als and the misfit gradient at every iteration. This procedure, denoted as wave-equation Q s i version (WQs), does not require the assumption of a layered model and tends to have fast and ro bust convergence compared to full waveform inversion (FWI). Numerical examples with syn thetic and field data demonstrate that the WQs method can accurately invert for a smoothed approximation t o the subsurface Q s

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Jing Li

Papers

Stratigraphy of the Von Kármán Crater Based on Chang'E-4 Lunar Penetrating Radar Data

Simulation of the Lunar Regolith and Lunar-Penetrating Radar Data Processing

Wave-equation Qs Inversion of Skeletonized Surface Waves

GPR simulation based on complex frequency shifted recursive integration PML boundary of 3D high order FDTD

Simulation and analysis of GPR signal based on stochastic media model with an ellipsoidal autocorrelation function