Lithospheric shear velocity structure of South Island, New Zealand, from amphibious Rayleigh wave tomography

Author Posting. © American Geophysical Union, 2016. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Solid Earth 121 (2016): 3686–3702, doi:10.1002/2015JB012726.We present a crust and mantle 3-D shear velocity model extending well offshore of New Zealand's South Island, imaging the lithosphere beneath the South Island as well as the Campbell and Challenger Plateaus. Our model is constructed via linearized inversion of both teleseismic (18–70 s period) and ambient noise-based (8–25 s period) Rayleigh wave dispersion measurements. We augment an array of 4 land-based and 29 ocean bottom instruments deployed off the South Island's east and west coasts in 2009–2010 by the Marine Observations of Anisotropy Near Aotearoa experiment with 28 land-based seismometers from New Zealand's permanent GeoNet array. Major features of our shear wave velocity (Vs) model include a low-velocity (Vs 50 km) beneath the central South Island exhibits strong spatial correlation with upper mantle earthquake hypocenters beneath the Alpine Fault. The ~400 km long low-velocity zone we image beneath eastern South Island and the inner Bounty Trough underlies Cenozoic volcanics and the locations of mantle-derived helium measurements, consistent with asthenospheric upwelling in the region.National Science Foundation Grant Number: EAR-0409564, EAR-0409609, and EAR-04098352016-11-2

Deep Underground Science and Engineering Laboratory - Preliminary Design Report

The DUSEL Project has produced the Preliminary Design of the Deep Underground Science and Engineering Laboratory (DUSEL) at the rehabilitated former Homestake mine in South Dakota. The Facility design calls for, on the surface, two new buildings - one a visitor and education center, the other an experiment assembly hall - and multiple repurposed existing buildings. To support underground research activities, the design includes two laboratory modules and additional spaces at a level 4,850 feet underground for physics, biology, engineering, and Earth science experiments. On the same level, the design includes a Department of Energy-shepherded Large Cavity supporting the Long Baseline Neutrino Experiment. At the 7,400-feet level, the design incorporates one laboratory module and additional spaces for physics and Earth science efforts. With input from some 25 science and engineering collaborations, the Project has designed critical experimental space and infrastructure needs, including space for a suite of multidisciplinary experiments in a laboratory whose projected life span is at least 30 years. From these experiments, a critical suite of experiments is outlined, whose construction will be funded along with the facility. The Facility design permits expansion and evolution, as may be driven by future science requirements, and enables participation by other agencies. The design leverages South Dakota's substantial investment in facility infrastructure, risk retirement, and operation of its Sanford Laboratory at Homestake. The Project is planning education and outreach programs, and has initiated efforts to establish regional partnerships with underserved populations - regional American Indian and rural populations

CMB-S4

We describe the stage 4 cosmic microwave background ground-based experiment CMB-S4

Investigation into the Deformatin of the Lithosphere Past and Present Using Passive Seismic Methods: Case Studies of the Wyoming Craton and South Island of New Zealand

In this thesis, I use passive source seismic data to image the crust and upper mantle in an effort to better understand how the lithosphere deforms. First, I examine how crustal shortening was accommodated during the Laramide orogeny in the Bighorn Mountain region of Wyoming. Second, I examine crustal and upper mantle deformation surrounding the Pacific-Australian plate boundary in the South Island of New Zealand. Laramide basement-cored foreland arches make up many prominent ranges in the eastern Rocky Mountains (USA). While thick-skinned Laramide shortening is easily observable at the surface, how shortening was accommodated at depth remains a first order question. A diverse variety of kinematic shortening models each predict a unique, modern-day crustal geometry and are therefore testable. I use teleseismic P-wave receiver functions to image basin and Moho structure in the Bighorn Mountain region. First, I develop and test a sequential H-κ (thickness-Vp/Vs) stacking algorithm to account for error introduced by low velocity sedimentary basins. Crustal thickness observations rule out models in which a ductile lower crust undergoes pure shear thickening, forming a crustal root, and models in which faults penetrate the Moho. A mismatch between the geometry of the Bighorn Arch at the surface and that of the Moho suggest that the upper and lower crust are poorly coupled and therefore casts doubt on models in which the whole lithosphere buckles. Kinematic models that invoke a major detachment fault remain feasible and suggest a pre-Laramide origin for the modern Moho structure. I use Rayleigh phase and group velocity observations from ambient noise to construct a regional 3D shear-velocity model and find that high-velocity lower crust appears absent beneath the Bighorn Mountains. Next, I focus on the modern day boundary between the Australian and Pacific plates on the South Island of New Zealand. I use continuous waveform data from ocean bottom seismometers to examine the anisotropic Rayleigh group velocity structure on and offshore of the South Island. Fast directions align sub-parallel to the Alpine Fault. Observations suggest distributed deformation of the lower crust and correlate well with seismic anisotropy observations of the mantle, suggesting the lower crust and mantle are well coupled

CMB-S4 Decadal Survey APC White Paper

International audienceWe provide an overview of the science case, instrument configuration and project plan for the next-generation ground-based cosmic microwave background experiment CMB-S4, for consideration by the 2020 Decadal Survey