I present a teleseismic waveform study of the lithospheric structure beneath the Tibetan Plateau, using data collected during the 1991-1992 SinoUS Tibet seismic recording experiment. Crustal thickness at each of the 11 broadband stations is estimated from the differential travel time between the Moho P -to-S converted phase and direct P . I demonstrated that this estimation is not sensitive to ...

We consider torsional oscillations of magnetars. This problem features rich dynamics due to the strong interaction between the normal modes of a magnetar’s crust and a continuum of Magneto-Hydro-Dynamic (MHD) modes in its fluid core. We study the dynamics using a simple model of a magnetar possessing a uniform magnetic field and a thin spherical crust. Firstly, we show that global torsional mod...

Southeastern Tibet marks the site of presumed clockwise rotation of the crust due to the India–Eurasian collision and abutment against the stable Sichuan basin and South China block. Knowing the structure of the crust is a key to better understanding of crustal deformation and seismicity in this region. Here, we analyze recordings of teleseismic earthquakes from 25 temporary broadband seismic s...

[1] Surface wave dispersion measurements from ambient seismic noise and array‐based measurements from teleseismic earthquakes observed with the EarthScope/USArray Transportable Array (TA) are inverted using a Monte Carlo method for a 3‐D VS model of the crust and uppermost mantle beneath the western United States. The combination of data from these methods produces exceptionally broadband dispe...

soil samples were collected from seven sites in and around the metropolitan area of mexicocity. the locations were chosen as possible sources of fugitive dusts which contribute to suspended particulate matter in the atmosphere of mexico city. x-ray fluorescence (xrf) was used to determine the concentrations of several major elements (si, k, ca, ti, mn, and fe), as well as of other trace element...

S U M M A R Y We have simultaneously inverted seismic refraction and wide-angle Moho reflection traveltimes for the 2-D crustal thickness and velocity structure of 150–300 kyr old crust along the East Pacific Rise (EPR) between the Siqueiros and Clipperton fracture zones (FZs). Our results show a strong correlation between ridge segmentation and upperand mid-crustal seismic velocities, with hig...

The simulated annealing method has recently been applied to several multiparameter optimization problems, including those of geophysical inversion. A new variant of simulated annealing, called very fast simulated annealing (VFSA), overcomes some of the drawbacks of a conventional simulated annealing; it has been found to be a practical tool for geophysical inversion (Sen & Stoffa 1995). The met...

S U M M A R Y The crustal structure beneath Ross Island and the Transantarctic Mountains (TAM) in Southern Victoria Land, Antarctica, is inferred using non-linear inversion of receiver functions, derived from teleseismic earthquake data. Intermediate-period waveforms from more than 160 teleseismic earthquakes recorded between January 1994 and January 2000 were used in the analysis. The inversio...

Eruptive sequences can be used as windows into the thermal and chemical evolution of magma chambers. We examined a continuous vertical section of the Baichahe basalt flow associated with the late Cenozoic Chifeng flood basalt in Inner Mongolia, North China. From oldest to youngest, MgO increases, K2O, light rare earths and other incompatible elements decrease, and Nb/La and radiogenic Pb isotop...

Metamorphic Core Complexes (MCCs) form when a thickened domain with a low-strength lower crust is submitted to extension. These structures are characteristic of post-orogenic extension, and field observations suggest that several MCCs rework a crustal nappe-stack emplaced before extension begins. These MCCs therefore develop within heterogeneous crusts that contain pre-existing dipping heteroge...