At the Cascadia margin the Juan de Fuca plate is subducting beneath the North America plate, causing active seismicity within both plates. Earthquakes occur down to a maximum depth of 80 km within the descending oceanic plate and to about 30 km in the overriding continental plate. We use a method of seismic tomography to invert 28,230 P wave arrival times from 2666 local earthquakes that occurr...

Using over 310,000 high-quality radial receiver functions recorded by the USArray and other seismic stations in the contiguous United States, the depths of the 410 km and 660 km discontinuities (d410 and d660) are mapped in over 1,000 consecutive overlapping circles with a radius of 1◦. The average mantle transition zone (MTZ) thickness for both the western and central/eastern U.S. is within 3 ...

We present a shear velocity model of the crust and upper mantle beneath central Eurasia by simultaneous inversion of broadband group and phase velocity maps of fundamental-mode Love and Rayleigh waves. The model is parameterized in terms of velocity depth profiles on a discrete 2◦ × 2◦ grid. The model is isotropic for the crust and for the upper mantle below 220 km but, to fit simultaneously lo...

S U M M A R Y We present a resolution study of the velocity structure beneath Iceland as constrained by teleseismic traveltime tomography using data from the HOTSPOT seismic network. This temporary PASSCAL network and the tomographic technique that was used to generate the ICEMAN velocity models are typical of regional seismic studies. Therefore, this study also provides a basis for understandi...

S U M M A R Y The dramatic asymmetry in terms of surface elevation, Cenozoic volcanisms and earthquake activity across the Red Sea is an enigmatic issue in global tectonics, partially due to the unavailability of broad-band seismic data on the African Plate adjacent to the Red Sea. Here, we report the first comprehensive image of the mantle transition zone (MTZ) discontinuities using data from ...

Newly discovered xenoliths within Pliocene and Quaternary intermediate volcanic rocks from southern Peru permit examination of lithospheric processes by which thick crust (60–70 km) and high average elevations (3–4 km) resulted within the Altiplano, the second most extensive orogenic plateau on Earth. The most common petrographic groups of xenoliths studied here are igneous or meta-igneous rock...

We present a frequency-independent three-dimensional (3-D) compressional wave attenuation model (indicated by the reciprocal of quality factor Qp) for Kı̄lauea Volcano in Hawai‘i. We apply the simul2000 tomographic algorithm to the attenuation operator t∗ values for the inversion of Qp perturbations through a recent 3-D seismic velocity model and earthquake location catalog. The t∗ values are me...

in this study we use the p receiver function technique to determine the moho depth and vp/vs ratio for 8 short period stations of qochan and mashhad seismic networks and map the variations of moho depth under kope dagh region. it is shown that a receiver function can provide a relatively good point measurement of moho depth under a short period station. the crustal thickness estimated from the ...