Arc magmas originate in subduction zones as partial melts of the mantle, induced by aqueous fluids/melts liberated by the subducted slab. Subsequently, they rise through and evolve within the overriding plate crust. Aside from broadly similar features that distinguish them from magmas of other geodynamic settings (e.g., mid-ocean ridges, intraplate), arc magmas display variably high Sr/Y values...

[1] We utilize seismic converted phases on more than 700 receiver functions calculated for 42 stations in the South Island, New Zealand, to infer crustal and uppermost mantle structure. We determine the crustal thickness from direct observations of conversion from the Moho interface and infer zone of the maximum thickness being located along the axis of the Southern Alps, just east from the Alp...

The shortand long-period body waves of five moderate (M L 5 to 6) earthquakes that took place in the nearshore region of southcentral California between 1969 and 1981 are modeled to obtain the source parameters. Both regional Pnl waveforms and teleseismic P waveforms are used in this analysis. Four of the events are thrust earthquakes with strikes that rotate southwestward as the epicenters mov...

We study the 3-D strain evolution of the northern Aegean and the vertical coherency of deformation. We observe that finite strain orientations in the mantle inferred from published shear-wave (SKS) fast polarization orientations, midto upper-crustal stretching lineations in metamorphic core complexes of mainly Miocene age, and the gradient in regional crustal thickness variations, are subparall...

[1] Subduction zones alter the upper plate in a variety of ways, including metasomatism via slab-derived fluids and accretion of exotic terranes. These processes should produce distinctive seismic signatures, as seismic velocities are sensitive to compositional variations. A new method is developed to estimates depths to interfaces and Poisson’s ratio (Vp/Vs ratio) for dipping layered structure...

The goal of the 1993 Los Angeles Region Seismic Experiment (LARSE93) passive phase was to collect waveform data from local and distant earthquakes to study lower crust and upper mantle structural features in southern California, particularly under the San Gabriel Mountains and San Andreas fault. During LARSE93, approximately 88 stations were deployed in a 175-km-long, linear array across the Lo...

The Na atmosphere of I0 requires a Na-S-O phase in the outer surface layers. Considering the various mechanisms for extraction of Na to the surface, the possible primary phases are Na20, Na2S•, and Na2SO4. However, regardless of the primary phases brought o the surface, the shallow cruslal recycling of material implied by the ongoing volcanism will tend to produce thermochemical equilibrium and...