Publications
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Ionospheric current source modeling and global geomagnetic induction using ground geomagnetic observatory data
Long-period global-scale electromagnetic induction studies of deep Earth conductivity are based almost exclusively on magnetovariational methods and require accurate models of external source spatial structure. We describe approaches to inverting for both the external sources and three-dimensional (3-D) conductivity variations and apply these methods to long-period (T≥1.2 days) geomagnetic observa
Authors
Jin Sun, Anna Kelbert, G. D. Egbert
Development of the Global Earthquake Model’s neotectonic fault database
The Global Earthquake Model (GEM) aims to develop uniform, openly available, standards, datasets and tools for worldwide seismic risk assessment through global collaboration, transparent communication and adapting state-of-the-art science. GEM Faulted Earth (GFE) is one of GEM’s global hazard module projects. This paper describes GFE’s development of a modern neotectonic fault database and a uniqu
Authors
Annemarie Christophersen, Nicola Litchfield, Kelvin Berryman, Richard Thomas, Roberto Basili, Laura Wallace, William Ries, Gavin P. Hayes, Kathleen M. Haller, Toshikazu Yoshioka, Richard D. Koehler, Dan Clark, Monica Wolfson-Schwehr, Margaret S. Boettcher, Pilar Villamor, Nick Horspool, Teraphan Ornthammarath, Ramon Zuñiga, Robert M. Langridge, Mark W. Stirling, Tatiana Goded, Carlos Costa, Robert Yeats
Blind identification of the Millikan Library from earthquake data considering soil–structure interaction
The Robert A. Millikan Library is a reinforced concrete building with a basement level and nine stories above the ground. Located on the campus of California Institute of Technology (Caltech) in Pasadena California, it is among the most densely instrumented buildings in the U.S. From the early dates of its construction, it has been the subject of many investigations, especially regarding soil–stru
Authors
S. F. Ghahari, F. Abazarsa, O. Avci, Mehmet Çelebi, E. Taciroglu
Hydrothermal alteration and diagenesis of terrestrial lacustrine pillow basalts: Coordination of hyperspectral imaging with laboratory measurements
We investigate an outcrop of ∼187 Ma lacustrine pillow basalts of the Talcott Formation exposed in Meriden, Connecticut, USA, focusing on coordinated analyses of one pillow lava to characterize the aqueous history of these basalts in the Hartford Basin. This work uses a suite of multidisciplinary measurements, including hyperspectral imaging, other spectroscopic techniques, and chemical and minera
Authors
Rebecca N Greenberger, John F Mustard, Edward A. Cloutis, Paul Mann, Janette H. Wilson, Roberta L Flemming, Kevin Robertson, Mark R Salvatore, Christopher Edwards
Regional seismic-wave propagation from the M5.8 23 August 2011, Mineral, Virginia, earthquake
The M5.8 23 August 2011 Mineral, Virginia, earthquake was felt over nearly the entire eastern United States and was recorded by a wide array of seismic broadband instruments. The earthquake occurred ~200 km southeast of the boundary between two distinct geologic belts, the Piedmont and Blue Ridge terranes to the southeast and the Valley and Ridge Province to the northwest. At a dominant period of
Authors
Fred Pollitz, Walter D. Mooney
Aurora painting pays tribute to Civil War's end
This year marks the sesquicentennial anniversary of the end of the American Civil War, a conflict that Abraham Lincoln called a “mighty scourge.” It was one of the most poignant periods in U.S. history, laying bare political, economic, social, and moral divergence between Northern and Southern states. The cause of the divergence that led to war was slavery [e.g., McPherson, 1988, chap. 3]—an insti
Authors
Jeffrey J. Love
A quick SEED tutorial
Introduction
A number of different government-funded seismic data centers offer free open-access data (e.g., U.S. Geological Survey, National Earthquake Information Center, the Incorporated Research Institutions for Seismology (IRIS), and Data Management System), which can be freely downloaded and shared among different members of the community (Lay, 2009). To efficiently share data, it is importa
Authors
Adam T. Ringler, John R. Evans
Scaling and design of landslide and debris-flow experiments
Scaling plays a crucial role in designing experiments aimed at understanding the behavior of landslides, debris flows, and other geomorphic phenomena involving grain-fluid mixtures. Scaling can be addressed by using dimensional analysis or – more rigorously – by normalizing differential equations that describe the evolving dynamics of the system. Both of these approaches show that, relative to ful
Authors
Richard M. Iverson
Widespread groundwater-level offsets caused by the Mw 5.8 Mineral, Virginia, earthquake of 23 August 2011
Groundwater levels were offset in bedrock observation wells, measured by the U.S. Geological Survey or others, as far as 553 km from the Mw 5.8 Mineral, Virginia (USA), earthquake on 23 August 2011. Water levels dropped as much as 0.47 m in 34 wells and rose as much as 0.15 m in 12 others. In some wells, which are as much as 213 m deep, the water levels recovered from these deviations in hours to
Authors
Evelyn A. Roeloffs, David L. Nelms, Rodney A. Sheets
Landslides and megathrust splay faults captured by the late Holocene sediment record of eastern Prince William Sound, Alaska
We present new marine seismic‐reflection profiles and bathymetric maps to characterize Holocene depositional patterns, submarine landslides, and active faults beneath eastern and central Prince William Sound (PWS), Alaska, which is the eastern rupture patch of the 1964 Mw 9.2 earthquake. We show evidence that submarine landslides, many of which are likely earthquake triggered, repeatedly released
Authors
S.P. Finn, Lee M. Liberty, Peter J. Haeussler, Thomas L. Pratt
Stress orientations in subduction zones and the strength of subduction megathrust faults
Subduction zone megathrust faults produce most of the world’s largest earthquakes. Although the physical properties of these faults are difficult to observe directly, their frictional strength can be estimated indirectly by constraining the orientations of the stresses that act on them. A global investigation of stress orientations in subduction zones finds that the maximum compressive stress axis
Authors
Jeanne L. Hardebeck
Slip pulse and resonance of Kathmandu basin during the 2015 Mw 7.8 Gorkha earthquake, Nepal imaged with space geodesy
Detailed geodetic imaging of earthquake rupture enhances our understanding of earthquake physics and induced ground shaking. The April 25, 2015 Mw 7.8 Gorkha, Nepal earthquake is the first example of a large continental megathrust rupture beneath a high-rate (5 Hz) GPS network. We use GPS and InSAR data to model the earthquake rupture as a slip pulse of ~20 km width, ~6 s duration, and with peak s
Authors
John Galetzka, D. Melgar, J.F. Genrich, J. Geng, S. Owen, E. O. Lindsey, X. Xu, Y. Bock, J.-P. Avouac, L. B. Adhikari, B. N. Upreti, B. Pratt-Sitaula, T. N. Bhattarai, B. P. Sitaula, A. Moore, Kenneth W. Hudnut, W. Szeliga, J. Normandeau, M. Fend, M Flouzat, L. Bollinger, P. Shrestha, B. Koirala, U. Gautam, M. Bhatterai, R. Gupta, T. Kandel, C. Timsina, S.N. Sapkota, S. Rajaure, N. Maharjan