Crustal plateaus and volcanic rises, major physiographic features on Venus, both formed over mantle plumes. Crustal plateaus were produced by large degrees of plume melting beneath thin lithosphere. The oldest tectonic features in crustal plateaus are ribbon-like troughs indicating early uplift and tensile stretching; their shallow depths suggest that surface temperature there was higher in the...

H-κ stacking is a routinemethod for determining crustal thickness (H) and Vp/Vs (κ) using P-to-S (Ps) receiver functions. In this paper we show that S-to-P (Sp) receiver functions may also be used to determine crustal parameters. Sp provides independent information, complementary to Ps. We develop a method called H-V (crustal thickness-velocity) stacking where Ps and Sp receiver functions are s...

This dissertation consists of four research topics, addressing three different scales of crustal-scale seismic data analysis. At the large scale, this research involves determining the lithospheric crustal structure across the southern Rio Grande rift (SRGR) from a 205 km long refraction/wide-angle reflection profile across southern New Mexico into Far West Texas acquired during the Portillo Vo...

Simultaneous modeling of source parameters and local layered earth structure for the April 29, 1965, Puget Sound earthquake was done using both ray and layer matrix formulations for point dislocations imbedded in layered media. The source parameters obtained are. dip 70 ° to the east, strike 344 °, rake -75 °, 63 km depth, average moment of 1.4 -10.6 X 10 ~6 dyne<m, and a triangular time functi...

crustal velocity structure model has a significant role in truly understanding of seismicity and also in relocating earthquakes. on the other hand, it can be used for recognizing major and potential seismic sources which is very critical for seismicity and earthquake hazard assessment studies. seismic parameters simultaneous inversion modeling is one of the most prevalent methods in the study o...

[1] The driving forces for crustal deformation are often inferred from the crustal kinematics. In the Southwestern United States, however, crustal kinematics delineated by the Global Positioning System (GPS) measurements differs significantly from that reconstructed from the geological records. This discrepancy is likely due to the different timescales reflected in these datasets. Here we explo...

Mantle convection patterns of the past are not well known, yet an understanding of changing mantle convection characteristics i fundamental to understanding the evolution of plate tectonics. There are very few ways to examine mantle characteristics of the past. Changes in spreading rate and volcanic activity with time have been used to draw conclusions about historic changes in mantle activity....

Small variations in gravity anomalies and topographic elevation observed in areas that have undergone highly variable amounts of upper crustal thinning can be satisfactorily explained by ductile flow of lower crustal material under the proper conditions. In this study we examine the boundary between the unextended Colorado Plateau and a strongly extended domain in the Basin and Range Province i...

The viscosity of lavas erupted at volcanic arcs varies over orders of magnitude. A comparison of the relative abundance of viscous lava dome eruptions indicates that the average viscosity of arc lavas also varies considerably between arcs. It is shown that for continental or transitional arcs with little within-arc crustal deformation and without underlying slab windows or tears, average lava v...

There is considerable controversy over the nature of geophysically recognized low-velocity-high-conductivity zones (LV-HCZs) within the Tibetan crust, and their role in models for the development of the Tibetan Plateau. Here we report petrological and geochemical data on magmas erupted 4.7-0.3 Myr ago in central and northern Tibet, demonstrating that they were generated by partial melting of cr...