Seismicity of the Wrangell and Aleutian Wadati‐Benioff Zones and the North American Plate along the Trans‐Alaska Crustal Transect, Chugach Mountains and Copper River Basin, southern Alaska

Page, Robert A.; Stephens, C. D.; Lahr, John C.

doi:10.1029/jb094ib11p16059

Cited by 109 publications

(83 citation statements)

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“…The module concept is the incorporation of an approach to data handling that differs from many other plate (Ratchkovski and Hansen, 2002;Page et al, 1989;Gudmundsson and Sambridge, 1998) relative to one-another and were appropriately smooth for input to the numerical simulation.…”

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confidence: 99%

A geoscience perspective on immersive 3D gridded data visualization

Billen

Kreylos

Hamann

et al. 2008

Computers & Geosciences

104

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We describe visualization software, Visualizer, that was developed specifically for interactive, visual exploration in immersive virtual reality (VR) environments. Visualizer uses carefully optimized algorithms and data structures to support the high frame rates required for immersion and the real-time feedback required for interactivity. As an application developed for VR from the ground up, Visualizer realizes benefits that usually can not be achieved by software initially developed for the desktop and later ported to VR. However, Visualizer can also be used on desktop systems (unix/linux based operating systems including Mac OS X) with a similar level of real-time interactivity, bridging the "software gap" between desktop and VR that has been an obstacle for the adoption of VR methods in the Geosciences. While many of the capabilities of Visualizer are already available in other software packages used in a desktop environment, the features that distinguish Visualizer are: 1) Visualizer can be used in any VR environment including the desktop, GeoWall, or CAVE, 2) In non-desktop environments the user interacts with the data set directly using a wand or other input devices instead of working indirectly via dialog boxes or text input, 3) On the desktop, Visualizer provides real-time interaction with very large data sets that can not easily be viewed or manipulated in other software packages. Three case studies are presented that illustrate the direct scientific benefits realized by analyzing data or simulation results with Visualizer in a VR environment. We also address some of the main obstacles to widespread use of VR environments in scientific research with a user study that shows Visualizer is easy to learn and to use in a VR environment and can be as effective on desktop systems as native desktop applications.

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confidence: 99%

A geoscience perspective on immersive 3D gridded data visualization

Billen

Kreylos

Hamann

et al. 2008

Computers & Geosciences

104

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“…Each field includes a typical entry, an abbreviated explanation, and the format for reading the field. For more details, refer to the sections indicated in the HYPOELLIPSE manual (Lahr, 1989). Note that the formats listed below for the "Station -time dependent" and "Archive arrival time" records are for the original non-Y2K version of HYPOELLIPSE where only a two-digit year is used and does not include the century.…”

Section: Summary Of Hypoellipse Data Formatsmentioning

confidence: 99%

“…Initial computer processing. The phase data for the timed events were batch processed by computer using the program HYPOELLIPSE (Lahr, 1989(Lahr, , 1999) to obtain origin times, hypocenters, magnitudes and, if desired, first-motion plots for fault-plane solutions. The HYPOELLIPSE computer program determines hypocenters by minimizing differences between observed and computed traveltimes through an iterative least-squares scheme.…”

Section: Data Processingmentioning

confidence: 99%

“…Over the years different methods have been used to account for variations in the crustal structure across southern Alaska. There have also been changes in the location program HYPOELLIPSE which would modify the computed locations (Lahr, 1989(Lahr, , 1999. For these reasons, all of the earthquake data from October 1971 through May 1989 were relocated using a single set of control parameters.…”

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Earthquake locations determined by the Southern Alaska seismograph network for October 1971 through May 1989

Fogleman¹,

Lahr²,

Stephens³

et al. 1993

Open-File Report

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For more information on the USGS-the Federal source for science about the Earth, its natural and living resources, natural hazards, and the environment-visit http://www.usgs.gov or call 1-888-ASK-USGS For an overview of USGS information products, including maps, imagery, and publications, visit http://www.usgs.gov/pubprodTo order this and other USGS information products, visit http://store.usgs.gov Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.Although this report is in the public domain, permission must be secured from the individual copyright owners to reproduce any copyrighted material contained within this report. Appendixes IntroductionThe U.S. Geological Survey (USGS) operated a regional network of seismographs in southern Alaska from 1971 to the mid 1990's. The principal purpose of this network was to record seismic data to be used to precisely locate earthquakes in the seismic zones of southern Alaska, delineate seismically active faults, assess seismic risks, document potential premonitory earthquake phenomena, investigate current tectonic deformation, and study the structure and physical properties of the crust and upper mantle. A task fundamental to all of these goals was the routine cataloging of parameters for earthquakes located within and adjacent to the seismograph network.The initial network of 10 stations, 7 around Cook Inlet and 3 near Valdez, was installed in 1971. In subsequent summers additions or modifications to the network were made. By the fall of 1973, 26 stations extended from western Cook Inlet to eastern Prince William Sound, and 4 stations were located to the east between Cordova and Yakutat. A year later 20 additional stations were installed. Thirteen of these were placed along the eastern Gulf of Alaska with support from the National Oceanic and Atmospheric Administration (NOAA) under the Outer Continental Shelf Environmental Assessment Program to investigate the seismicity of the outer continental shelf, a region of interest for oil exploration. Since then the region covered by the network remained relatively fixed while efforts were made to make the stations more reliable through improved electronic instrumentation and strengthened antenna systems. The majority of the stations installed since 1980 were operated only temporarily (from one to several years) for special studies in various areas within the network. Due to reduced funding, the network was trimmed substantially in the summer of 1985 with the closure of 15 stations, 13 of which were located in and around the Yakataga seismic gap. To further reduce costs, two telephone circuits were dropped and multiple radio relays were installed in their place. This economy reduced the reliability of these telemetry links. In addition, data collection from the areas around Cordova and Yakutat was compromised by 2 the necessity of relying on triggered event recording using PC-based systems (Rogers, 1993) that were not fully developed and which proved t...

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“…The subducting plate geometry is based on Wadati-Benioff zone seismicity, seismic reflection and refraction, and seismic tomography [27,11,28,8]. The temperatures for the subducting and overriding plates are based on geologic and geophysical observables, thereby capturing the regional variability specific to this particular plate boundary system, as in [26,20,4,16,17].…”

Section: Set-up For Complex 3d Model Of Alaska Subduction Zonementioning

confidence: 99%

Three-dimensional simulations of geometrically complex subduction with large viscosity variations

Jadamec

Billen

Kreylos

2012

Proceedings of the 1st Conference of the Extreme Science and Engineering Discovery Environment: Bridging From the eXtreme to Th

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The incorporation of geologic realism into numerical models of subduction is becoming increasingly necessary as observational and experimental constraints indicate plate boundaries are inherently three-dimensional (3D) in nature and contain large viscosity variations. However, large viscosity variations occurring over short distances pose a challenge for computational codes, and models with complex 3D geometries require substantially greater numbers of elements, increasing the computational demands. We modified a community mantle convection code, CitcomCU, to model realistic subduction zones that use an arbitrarily shaped 3D plate boundary interface and incorporate the effects of a strainrate dependent viscosity based on an experimentally derived flow law for olivine aggregates. Tests of this implementation on 3D models with a simple subduction zone geometry indicate that limiting the overall viscosity range in the model, as well as limiting the viscosity jump across an element, improves model runtime and convergence behavior, consistent with what has been shown previously. In addition, the choice of method and averaging scheme used to transfer the viscosity structure to the different levels in the multigrid solver can significantly improve model performance. These optimizations can improve model runtime by over 20%. 3D models of a subduction zone with a complex plate boundary geometry were then constructed, containing over 100 million finite element nodes with a local resolution of up to 2.35 km, and run on XSEDE. These complex 3D models, representative of the Alaska subduction zone-transform plate boundary, contain viscosity variations of up to seven orders of magnitude. The optimizations in solver parameters determined from the simple 3D models of subduction applied to the much larger and more complex models of an actual subduction zone im- * Corresponding author.Permission to make digital or hard copies of all or part of this work for personal or classroom use is granted without fee provided that copies are not made or distributed for profit or commercial advantage and that copies bear this notice and the full citation on the first page. To copy otherwise, to republish, to post on servers or to redistribute to lists, requires prior specific permission and/or a fee. proved model convergence behavior and reduced runtimes by on the order of 25%. One scientific result from 3D models of Alaska is that a laterally variable mantle viscosity emerges in the mantle as a consequence of variations in the flow field, with localized velocities of greater than 80 cm/yr occurring close to the subduction zone where the negative buoyancy of the slab drives the flow. These results are a significant departure from the paradigm of two-dimensional (2D) models of subduction where the slab velocity is often fixed to surface plate motion. While the solver parameter optimization can improve model performance, the results also demonstrate the need for new solvers to keep pace with the demands for increasingly complex numerical...

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Seismicity of the Wrangell and Aleutian Wadati‐Benioff Zones and the North American Plate along the Trans‐Alaska Crustal Transect, Chugach Mountains and Copper River Basin, southern Alaska

Cited by 109 publications

References 36 publications

A geoscience perspective on immersive 3D gridded data visualization

A geoscience perspective on immersive 3D gridded data visualization

Earthquake locations determined by the Southern Alaska seismograph network for October 1971 through May 1989

Three-dimensional simulations of geometrically complex subduction with large viscosity variations

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