PASSCAL Experiments http://www.passcal.nmt.edu/rss/experiments en Banda Arc http://www.passcal.nmt.edu/scheduledetails/exptnumb/201412 Eastern Indonesia is one of the least well understood geological domains of our planet, and yet the region provides a truly remarkable natural experiment for unraveling the complex dynamics of convergent tectonics. The recent, subduction-related collision of the Australian continental lithosphere with the active Banda arc effectively captures the initiation of convergence orogenesis and offers a rare glimpse into a process that has shaped Earth’s evolution over geologic time, as well as providing fresh insights into seismic hazards confronting the world’s fourth most populous country. A number of mysteries remain about the transition from subduction to arc-continental collision in the Banda arc, reflecting fundamental gaps in the general understanding of collisional tectonics. DRRISWIV - WINTER (DRIS) http://www.passcal.nmt.edu/scheduledetails/exptnumb/201424 Ocean gravity waves are dynamic, changeable elements of the global ocean environment, affected by ocean warming and changes in ocean and atmospheric circulation patterns. Their evolution may thus drive changes in ice-shelf stability by both mechanical interactions, and potentially increased basal melting, which in turn feed back on sea level rise. Our proposed research is intended to discover, through field observations and numerical simulations, how ocean wave-induced vibrations on ice shelves in general, and the Ross Ice Shelf (RIS), in particular, can be used to infer spatial and temporal variability of ice shelf mechanical properties. The mechanical forcing to be examined involves a broad spectrum of surface gravity waves spanning local wind seas (at periods less than 10 s), sea swell (in the 10 - 30 s period band), and infragravity (IG) waves (periods from about 50 to 300 s). Sweetwater http://www.passcal.nmt.edu/scheduledetails/exptnumb/201429 Collaborative experiments with NodalSeismic and Nanometrics to conduct a mix phase array of continuous recorded nodes with broadband sensors. AAA (triple A) http://www.passcal.nmt.edu/scheduledetails/exptnumb/201502 Four mini seismic arrays will be installed in Unalaska Island. They will image a variety of seismic events from the subduction zone including tremor, low frequency earthquakes associated with slow earthquakes and regular fast earthquakes. They will also capture events from nearby volcanoes (Makushin and Akutan) allowing us to better understand the volcanic plumbing systems. The arrays are designed to simultaneously image both subduction and volcanic system. Ross Ice Shelf (RIS) http://www.passcal.nmt.edu/scheduledetails/exptnumb/201425 We will deploy 18 autonomous broadband seismographs provided by the IRIS PASSCAL program for two continuous years on the Ross Ice Shelf (RIS) between Ross Island and MBL to constrain the mantle structure and dynamics of the Ross Sea Embayment. These stations would take advantage of the presence of the ice shelf to fill a major ocean-covered geological gap within Earth's least studied extensional continental province and would link data sets collected in the TAM transition/Plateau region (TAMSEIS) and in West Antarctica (POLENET) to greatly improve resolution of mantle features beneath Antarctica. Deployment on the ice shelf offers the opportunity to collect seismic data without the expense, logistical complexity, and iceberg hazards associated with ocean bottom seismograph deployments, and limited pioneering deployments on the ice shelf show excellent recording of P waves and 8-50 s Rayleigh waves. Tomographic models developed from this data will be used to choose between competing models for the dynamics of the Ross Sea. In particular, we will investigate whether low velocity hot mantle is localized in the vicinity of Ross Island and the MBL Dome. Alternatively, a broad region of hot mantle, including the Eastern Ross Sea, would indicate distributed recent tectonic activity and call into question models proposing that Eastern Ross extension ceased during the Mesozoic. These data will also allow us to investigate the deeper structure (gt 200 km) to evaluate the possible role of mantle plumes and/or small- scale convection in driving regional volcanism and tectonism across the region. MAGIC http://www.passcal.nmt.edu/scheduledetails/exptnumb/201404 The Mid-Atlantic Geophysical Integrative Collaboration (MAGIC) experiment aims to characterize lithospheric structure, mantle flow, and topographic evolution of the southeastern US continental margin from the Atlantic coast to the continental interior. Cascadia Initiative http://www.passcal.nmt.edu/scheduledetails/exptnumb/201430 This deployment of approximately 15 broadband instruments is to complement the focused OBS array of the Cascadia Initiative. Beginning in July 2014, 20 OBS will be deployed offshore this region with approximate station spacing of 10-15 km. We want to record on land with a comparable station spacing for as long as possible during the 12-15 month OBS deployment. DC Shake http://www.passcal.nmt.edu/scheduledetails/exptnumb/201437 A ~30-station array in the Washington, DC area to measure variations in ground shaking (site response) due to local variations in the shallow geology. SEGMeNT http://www.passcal.nmt.edu/scheduledetails/exptnumb/201302 This experiment will acquire a family of geophysical, geochemical and geological observations in and around northern Lake Malawi to test fundamental hypotheses regarding continental rupture. Together, these data will allow us to characterize extensional deformation and magmatism at depth in the crust, mantle lithosphere and upper asthenosphere. These include seismic reflection data, onshore/offshore wide-angle seismic reflection/refraction data, passive seismic data (including body waves and surface waves), seismicity, long-period and wide-band MT data, continuous GPS data, InSAR data, and geochemical data. The IRIS PASSCAL component consists of 40 BB stations and 16 IP stations deployed for a period of 18 months. Mt St Helens http://www.passcal.nmt.edu/scheduledetails/exptnumb/201405 Seismic tomography experiment of the Mt St Helens volcanic system. Project consists of 2 orthogonal refraction profiles and 4 areal surveys to record 24 shots. Target goals are to illuminate the upper, middle, and lower crust of the Mt St Helens volcanic system.