To investigate the nature of Pn propagation, we have implemented the spectral-element method (SEM) for vertically and laterally varying media with and without attenuation. As a practical measure, essential features of the Pn waves are distilled into seismic attributes including arrival times, amplitudes and pulse frequencies. To validate the SEM simulations, we first compare the SEM results wit...

Seismic behaviour of steel-concrete composite high-rise buildings, composed of external steel frames (SF) and internal concrete tube (CT), with rectangular plan is investigated in this paper. A macro-element based model is established for seismic analysis of composite high-rise buildings aiming at predicting their global responses under earthquakes. By employing this macro-element based model, ...

The purpose of this paper is to present the fundamentally basic aspects of source spectra through the preliminary use of the one-dimensional Haskell source model which assumes a finite fault with a constant rupture velocity. Teleseismic distances are assumed, such that the far field term dominates, allowing the P and S waves emanating from the source to be effectively considered double couple p...

Ambient noise in the eastern Arctic was studied from April to September 2013 using a 22 element vertical hydrophone array as it drifted from near the North Pole (89° 23'N, 62° 35'W) to north of Fram Strait (83° 45'N, 4° 28'W). The hydrophones recorded for 108 min/day on six days per week with a sampling rate of 1953.125 Hz. After removal of data corrupted by non-acoustic transients, 19 days thr...

High-resolution seismic reflection methods were instrumental in characterizing a coalbed methane prospect estimated to have the potential to produce sufficient methane to satisfy the municipal needs of rural Fort Yukon, Alaska. Reflections with upper corner frequencies over 200 Hz and dominant frequencies over 150 Hz were recorded sitewide. Over a dozen uniquely distinguishable reflections are ...

Three amplification mechanisms of large accelerations over 20 m/s2 are related to various non-liner behaviors and explained by using the non-stationary Fourier spectra. The frequencies of dominant components are compared with the natural frequencies with the ratios (1:3:5:7) of a shear-spring model of the underground soil. Thus, one of the amplification mechanisms is supposed to result from the...

Many of the geophysical data analysis problems, such as signal-noise separation and data regularization, are conveniently formulated in a transform domain, where the signal appears sparse. Classic transforms such as the Fourier transform or the digital wavelet transform, fail occasionally in processing complex seismic wavefields, because of the nonstationarity of seismic data in both time and s...