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  • 1
    Publication Date: 2017-08-31
    Description: We performed relative locations of six event-pairs based on surface-wave (SW) and body-wave (BW) differential travel-times of the 2016-09-09, 2016-01-06, 2013-02-12, and 2009-05-25 announced North Korea nuclear explosions. The SW relative locations for the 2009-05-25 and 2013-02-12 events were inconsistent with the BWs when paired with other events and only the 2016-01-06/2016-09-09 pair was consistent. Apparent SW phase shift is investigated with respect to the BW relative locations. The pairs formed with the 2009-05-25 and 2013-02-12 events, beneath the southeast slope of Mount Mant'ap, have the largest phase shifts and amplitude ratio deviations, whereas the least deviation was from the 2016-01-06 and 2016-09-09 event-pair beneath the mountain peak. Regional moment tensors (MTs) predict the amplitude ratios but do not resolve the relative phase. We find MTs with 10% difference in isotropic and rotated +CLVD can fit both relative phase and amplitude ratios. SW relative locations of highly isotropic and correlated explosion clusters can be affected by topography and small differences in MT.
    Print ISSN: 0094-8276
    Electronic ISSN: 1944-8007
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 2
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    In:  Bull. Seism. Soc. Am., Minsk, Elsevier Science Publishers B.V., vol. 90, no. 1, pp. 199-211, pp. 2443, (ISSN: 1340-4202)
    Publication Date: 2000
    Keywords: Seismology ; Seismic networks ; Location ; Teleseismic events ; Data analysis / ~ processing ; BSSA
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  • 3
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    In:  Phys. Earth Plan. Int., Wiesbaden, Franz Steiner Verlag GmbH, vol. 113, no. 1, pp. 321-338, pp. L10308, (ISSN: 1340-4202)
    Publication Date: 1999
    Keywords: Seismology ; Detectors ; Location ; Discrimination ; Data analysis / ~ processing ; Error analysis ; PEPI ; identical ; to ; Schultz ; ++ ; 1998
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  • 4
    Publication Date: 2012-10-06
    Description: We develop a global-scale P wave velocity model (LLNL-G3Dv3) designed to accurately predict seismic travel times at regional and teleseismic distances simultaneously. The model provides a new image of Earth's interior, but the underlying practical purpose of the model is to provide enhanced seismic event location capabilities. The LLNL-G3Dv3 model is based on ∼2.8 million P and Pn arrivals that are re-processed using our global multiple-event locator called Bayesloc. We construct LLNL-G3Dv3 within a spherical tessellation based framework, allowing for explicit representation of undulating and discontinuous layers including the crust and transition zone layers. Using a multiscale inversion technique, regional trends as well as fine details are captured where the data allow. LLNL-G3Dv3 exhibits large-scale structures including cratons and superplumes as well numerous complex details in the upper mantle including within the transition zone. Particularly, the model reveals new details of a vast network of subducted slabs trapped within the transition beneath much of Eurasia, including beneath the Tibetan Plateau. We demonstrate the impact of Bayesloc multiple-event location on the resulting tomographic images through comparison with images produced without the benefit of multiple-event constraints (single-event locations). We find that the multiple-event locations allow for better reconciliation of the large set of direct P phases recorded at 0–97° distance and yield a smoother and more continuous image relative to the single-event locations. Travel times predicted from a 3-D model are also found to be strongly influenced by the initial locations of the input data, even when an iterative inversion/relocation technique is employed.
    Print ISSN: 0148-0227
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 5
    Publication Date: 2011-04-13
    Description: We extend the Bayesloc seismic multiple-event location algorithm for application to global arrival time data sets. Bayesloc is a formulation of the joint probability distribution spanning multiple-event location parameters, including hypocenters, travel time corrections, pick precision, and phase labels. Stochastic priors may be used to constrain any of the Bayesloc parameters. Markov Chain Monte Carlo sampling is used to draw samples from the joint probability distribution, and the posteriori samples are summarized to infer conventional location parameters such as the hypocenter. The first application of the broad area Bayesloc algorithm is to a data set consisting of all well-recorded events in the Middle East and the most well-recorded events with 5° spatial sampling globally. This sampling strategy is designed to provide the ray coverage needed to determine lithospheric-scale P wave velocity structure in the Middle East using the complementary ray geometry provided by regional (subhorizontal) and teleseismic (subvertical) raypaths and to determine a consistent, albeit lower-resolution, image of global mantle structure. The data set consists of 5401 events and 878,535 P, Pn, pP, sP, and PcP arrivals recorded at 4606 stations. Relocated epicenters are an average of 16 km from bulletin locations. The data set included events that are known to an accuracy of 1 km (a.k.a. GT1) based on nonseismic information. The average distance between GT1 epicenters and our relocated epicenters is 5.6 km. For arrivals labeled P, Pn, and PcP, ∼92%, ∼90%, and 96% are properly labeled with probability 〉0.9, respectively. Incorrect phase labels are found to be erroneous at rates of 0.6%, 0.2%, 1.6%, and 2.5% for P, Pn, PcP, and depth phases (pP and sP), respectively. Labels found to be incorrect, but not erroneous, were reassigned to another phase label. P and Pn residual standard deviation with respect to ak135 travel times are dramatically reduced from 3.45 s to 1.01 s. The differences between travel time residuals for nearly reciprocal raypaths are significantly reduced from the input event locations, suggesting that Bayesloc relocation improves data set consistency. The reciprocity tests suggest that the dominant contribution to travel time residuals calculated from information provided in global bulletins is location and picks errors, not travel time prediction errors due to 3-D structure. Modeling the whole multiple-event system results in accurate locations and an internally consistent data set that is ideal for tomography and other travel time calibration studies. Simmons et al. (2011) (companion paper) use the Bayesloc-processed data set to develop a 3-D tomographic image, which further reduces residual standard deviation to 0.50 s.
    Print ISSN: 0148-0227
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 6
    Publication Date: 2011-04-13
    Description: We construct a model of three-dimensional P wave velocity structure in the crust and mantle that is global in extent, but with detailed upper mantle heterogeneities throughout the greater Middle East region. Fully three-dimensional ray tracing is employed to achieve accurate travel time predictions of P and Pn arrivals, requiring the characterization of irregular and discontinuous boundaries. Therefore, we explicitly represent undulating seismic discontinuities in the crust and upper mantle within a spherical tessellation modeling framework. The tessellation-based model architecture is hierarchical in that fine node sampling is achieved by recursively subdividing a base level tessellation. Determining the required node spacing to effectively model a given set of data is problematic, given the uneven sampling of seismic data and the differing wavelengths of actual seismic heterogeneity. To address this problem, we have developed an inversion process called Progressive Multilevel Tessellation Inversion (PMTI) that exploits the hierarchical nature of the tessellation-based design and allows the data to determine the level of model complexity. PMTI serves as an alternative to existing multiresolution approaches and robustly images regional trends while allowing localized details to emerge where resolution is sufficient. To demonstrate our complete modeling concept, we construct a velocity model based on teleseismic P travel time data for global events and regional Pn travel time data for events occurring throughout the Middle East. Input data are a product of the statistical procedure called Bayesloc that simultaneously models all components of a multievent system including event locations, origin times, and arrival times (described in the Myers et al. (2011) companion paper). The initial tomographic image provides a new glimpse of the complex upper mantle velocity anomalies associated with the convergence of the Arabian and Indian plates with Eurasia. More important for event monitoring, the model accurately predicts both teleseismic and regional travel times for events occurring within the Middle East region.
    Print ISSN: 0148-0227
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 7
    Publication Date: 1999-12-11
    Description: Tubby-like proteins (TULPs) are found in a broad range of multicellular organisms. In mammals, genetic mutation of tubby or other TULPs can result in one or more of three disease phenotypes: obesity (from which the name "tubby" is derived), retinal degeneration, and hearing loss. These disease phenotypes indicate a vital role for tubby proteins; however, no biochemical function has yet been ascribed to any member of this protein family. A structure-directed approach was employed to investigate the biological function of these proteins. The crystal structure of the core domain from mouse tubby was determined at a resolution of 1.9 angstroms. From primarily structural clues, experiments were devised, the results of which suggest that TULPs are a unique family of bipartite transcription factors.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Boggon, T J -- Shan, W S -- Santagata, S -- Myers, S C -- Shapiro, L -- New York, N.Y. -- Science. 1999 Dec 10;286(5447):2119-25.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Structural Biology Program, Department of Physiology and Biophysics, Ruttenberg Cancer Center, Mount Sinai School of Medicine of New York University, New York, NY 10029, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10591637" target="_blank"〉PubMed〈/a〉
    Keywords: Adaptor Proteins, Signal Transducing ; Alternative Splicing ; Amino Acid Sequence ; Animals ; Cell Line ; Cell Nucleus/chemistry ; Crystallography, X-Ray ; DNA/metabolism ; Eye Proteins/*chemistry/genetics/*metabolism ; Humans ; Models, Molecular ; Molecular Sequence Data ; Protein Conformation ; Protein Structure, Secondary ; Protein Structure, Tertiary ; Proteins/*chemistry/genetics/*metabolism ; Recombinant Proteins/chemistry/metabolism ; Sequence Alignment ; Transcription Factors/*chemistry/genetics/*metabolism ; Transcriptional Activation
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 8
    Publication Date: 1995-04-07
    Description: The M(w) = 8.3 deep (636 kilometers) Bolivian earthquake of 9 June 1994 was the largest deep-focus earthquake ever recorded. Seismic data from permanent stations plus portable instruments in South America show that rupture occurred on a horizontal plane and extended at least 30 by 50 kilometers. Rupture proceeded at 1 to 3 kilometers per second along the down-dip azimuth of the slab and penetrated through more than a third of the slab thickness. This extent is more than three times that expected for a metastable wedge of olivine at the core of the slab, and thus appears to be incompatible with an origin by transformational faulting. These large events may instead represent slip on preserved zones of weakness established in oceanic lithosphere at the Earth's surface.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Silver, P G -- Beck, S L -- Wallace, T C -- Meade, C -- Myers, S C -- James, D E -- Kuehnel, R -- New York, N.Y. -- Science. 1995 Apr 7;268(5207):69-73.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/17755232" target="_blank"〉PubMed〈/a〉
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 9
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Descriptions of the seasonal cycles of abundance of the dominant zooplankters of Yaquina Bay, Oregon, USA, are derived from a 7 year series of net samples taken at two downstream stations. The summer dominants are forms distributed to the north, along the American coast. Winter dominants have sonthern affinities. This cycle is associated with the annual cycle of coastal surface currents: from north to south in summar, reversed in winter. There are no persistent trends in the abundance data from year-to-year.
    Type of Medium: Electronic Resource
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  • 10
    Publication Date: 2015-06-09
    Description: A global validation dataset of 116 seismic events and 20,977 associated Pn and P arrivals is used to assess travel-time prediction and event location accuracy for the global-scale, 3D, P -wave velocity model called LLNL-G3Dv3 ( Simmons et al. , 2012 ). Strong regional trends that are observed for ak135 travel-time residuals are largely removed when LLNL-G3Dv3 is used for prediction. The 25th–75th quantile spread of travel-time residuals is reduced by 30%–40% at teleseismic distances, and the spread is reduced by ~60% at regional distances (〈16°). Epicenter error decreases when more data are used to constrain event locations until more than ~40 arrivals times are used. At which point, epicenter error reduction tends to plateau. Median epicenter errors for the ak135 and LLNL-G3Dv3 models plateau at ~8.0 and ~5.5 km, respectively, for teleseismic P datasets. Median epicenter errors for the ak135 and LLNL-G3Dv3 models plateau at ~12.0 and ~4.0 km, respectively, for regional Pn datasets. We demonstrate that spatially correlated travel-time residual errors for the ak135 model lead to increasing epicenter error when ~40 to ~100 Pn arrivals are used to constrain the location. The effect of correlated error is mitigated by LLNL-G3Dv3, for which epicenter error steadily decreases to ~4 km when 100 Pn arrivals are used. The median area of 0.95 epicenter probability bounds for ak135 and LLNL-G3Dv3 are 1811 and 758 km 2 , respectively. The ak135 ellipses are inflated to achieve the desired rate of true events occurring inside the probability region, whereas LLNL-G3Dv3 error ellipses based on empirical residual distributions cover the true location at the expected rate because location bias is minimal.
    Print ISSN: 0037-1106
    Electronic ISSN: 1943-3573
    Topics: Geosciences , Physics
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