[1] Volcanic SO2 can affect the Earth’s environment. Where no direct measurements of SO2 in the atmosphere are available, a petrologic method of assessing sulfur release from the magma must be used. However, in studies of arcderived eruptions, satellite-based measurements of SO2 emissions using Total Ozone Mapping Spectrometer (TOMS) data are orders of magnitude greater than those calculated pe...

Abstract Ordovician and Silurian siliciclastic, volcanic, plutonic rocks in the southern Appalachian eastern Blue Ridge western Inner Piedmont, formerly interpreted as components of an obducted Taconic arc terrane, are recognized parts paired arc/back-arc system that formed on seaward edge Laurentian plate. New crystallization ages from metamorphosed plutonic-volcanic intruding intercalated wit...

Subducting slabs carry water into the mantle and are a major gateway in the global geochemical water cycle. Fluid transport and release can be constrained with seismological data. Here we use joint active-source/local-earthquake seismic tomography to derive unprecedented constraints on multi-stage fluid release from subducting slow-spread oceanic lithosphere. We image the low P-wave velocity cr...

The Nazca, Caribbean, and South America plates meet in northwestern South America where the northern end of the Andean volcanic arc and Wadati-Benioff zone seismicity indicate ongoing subduction. However, the termination of Quaternary volcanism at ~5.5°N and eastward offset in seismicity underneath Colombia suggest the presence of complex slab geometry. To help link geometry to dynamics, we ana...

Tomographic images of the distribution of shear wave speed beneath the northwestern Pacific delineate the configuration of the subducted oceanic lithosphere beneath the western Aleutian Arc. At ~100 km depth, a fast shear wave speed anomaly lies beneath the Aleutian Arc everywhere east of 173E. Between 164E and 173E, however, seismic velocities at this depth are slow relative to the surrounding...