120 research outputs found

    Hypocenter estimation for 14 earthquakes in south-central Alaska (1929-1975)

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    We provide results from an analysis of 14 historical earthquakes in the region of Cook Inlet and Susitna, south-central Alaska. Using global arrival times of P and S waves, we estimate probabilistic hypocenters using the code NonLinLoc. We provide the complete results, as well as a set of plots to help interpret the likelihood of each earthquake being within the crust, on the subduction interface, or within the subducting Pacific slab.V. Silwal and C. Tape were supported by USGS Earthquake Hazards Program (contract G15AP00052)

    The intrinsic shapes of starless cores in Ophiuchus

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    Using observations of cores to infer their intrinsic properties requires the solution of several poorly constrained inverse problems. Here we address one of these problems, namely to deduce from the projected aspect ratios of the cores in Ophiuchus their intrinsic three-dimensional shapes. Four models are proposed, all based on the standard assumption that cores are randomly orientated ellipsoids, and on the further assumption that a core's shape is not correlated with its absolute size. The first and simplest model, M1, has a single free parameter, and assumes that the relative axes of a core are drawn randomly from a log-normal distribution with zero mean and standard deviation \sigma o. The second model, M2a, has two free parameters, and assumes that the log-normal distribution (with standard deviation \sigma o) has a finite mean, \mu o, defined so that \mu o<0 means elongated (prolate) cores are favoured, whereas \mu o>0 means flattened (oblate) cores are favoured. Details of the third model (M2b, two free parameters) and the fourth model (M4, four free parameters) are given in the text. Markov chain Monte Carlo sampling and Bayesian analysis are used to map out the posterior probability density functions of the model parameters, and the relative merits of the models are compared using Bayes factors. We show that M1 provides an acceptable fit to the Ophiuchus data with \sigma o ~ 0.57+/-0.06; and that, although the other models sometimes provide an improved fit, there is no strong justification for the introduction of their additional parameters.Comment: 10 pages, 8 figures. Accepted by MNRA

    Suspiciously Significant Nonsense: A (Queer) Analysis of John Weinzweig's Private Collection Through Lip-Synced Performance

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    This thesis presents two different analyses of John Weinzweigs Private Collection, a group of nine songs for soprano and piano that was completed in 1975. The first analysis is text-based and draws on the existing literature, my own reading of the score, and archival research. The second is a performance-based analysis focused on a lip-synced performance of Mary Lou Fallis and Monica Gaylords recording of the composition, which I personally directed. I also draw upon data collected from audience surveys and performer interviews in this analysis. Here I consider various layers of performativity in Private Collection and ground my work in performance studies and queer scholarship. I argue that lip-syncing is a queer methodology that can illuminate the fragmented and multiple meanings that emerge from recorded music

    Synthetic observations of protostellar multiple systems

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    Observations of protostars are often compared with synthetic observations of models in order to infer the underlying physical properties of the protostars. The majority of these models have a single protostar, attended by a disc and an envelope. However, observational and numerical evidence suggests that a large fraction of protostars form as multiple systems. This means that fitting models of single protostars to observations may be inappropriate. We produce synthetic observations of protostellar multiple systems undergoing realistic, non-continuous accretion. These systems consist of multiple protostars with episodic luminosities, embedded self-consistently in discs and envelopes. We model the gas dynamics of these systems using smoothed particle hydrodynamics and we generate synthetic observations by post-processing the snapshots using the SPAMCART Monte Carlo radiative transfer code. We present simulation results of three model protostellar multiple systems. For each of these, we generate 4 × 104 synthetic spectra at different points in time and from different viewing angles. We propose a Bayesian method, using similar calculations to those presented here, but in greater numbers, to infer the physical properties of protostellar multiple systems from observations

    Trekking to the Tenure Finish Line: Teacher Educators and the Power of Peer Mentoring at an HBCU

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    The educator\u27s primary goal is to ensure student success by offering dynamic student experiences that will allow the students to synthesize their new learning with hopes of practical application. In higher education, a professor can easily fall into working in isolation due to the uniqueness of course offerings and areas of professional interest. However, when professors consciously build professional peer-mentoring relationships with colleagues that have similar interests and core values, both professors can grow. For example, when an experienced tenure track professor with K12 experience partners with a novice tenure track professor with over a decade of experience in education leadership, wonderful things can happen. This article details the first- and fifth-year experiences of two tenure track professors at an Historically Black College and University (HBCU) in the mid-Atlantic region. Instruction and scholarship, work-life balance, and relationships with students are areas of impact as an outcome of this peer-mentoring relationship

    Tsunami early warning using earthquake rupture duration, Geophys

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    [1] Effective tsunami early warning for coastlines near a tsunamigenic earthquake requires notification within 5 -15 minutes. We have shown recently that tsunamigenic earthquakes have an apparent rupture duration, T 0 , greater than about 50 s. Here we show that T 0 gives more information on tsunami importance than moment magnitude, M w , and we introduce a procedure using seismograms recorded near an earthquake to rapidly determine if T 0 is likely to exceed T = 50 or 100 s. We show that this &apos;&apos;duration-exceedance&apos;&apos; procedure can be completed within 3-10 min after the earthquake occurs, depending on station density, and that it correctly identifies most recent earthquakes which produced large or devastating tsunamis. This identification forms a complement to initial estimates of the location, depth and magnitude of an earthquake to improve the reliability of tsunami early warning, and, in some cases, may make possible such warning. Citation: Lomax, A., and A. Michelini (2009), Tsunami early warning using earthquake rupture duration, Geophys. Res. Lett., 36, L09306

    High-precision earthquake locations in Switzerland using regional secondary arrivals in a 3-D velocity model

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    We present a new approach to relocate earthquakes in the greater western Alpine region using main crustal phases (Pg, Pn, PmP) that takes advantage of recent developments in P-wave velocity models and modelling of the Moho topography in the region, as well as the ability to track reflected and refracted phases in three-dimensional (3-D) heterogeneous media. Our approach includes a new 3-D P-wave velocity model for Switzerland and surrounding regions that combines a first-order Moho discontinuity based on local earthquake tomography (LET) and controlled-source seismology (CSS) information and 3-D seismic velocity information based on LET. Traveltimes for the main crustal phases (Pg, Pn, PmP) are computed using a fast marching method. We use a non-linear, probabilistic approach to relocate earthquakes that has been extended to include the use of secondary phases. We validate our approach using synthetic data, which was computed for a real earthquake and different combinations of available phases (Pg, Pn, PmP). We also applied our approach to relocate four selected earthquakes, two shallow and two deep crustal events in the northern Alpine foreland, for which independent information (ground truth information) on their focal depths exist. Our results demonstrate that the precision and accuracy of focal depth estimates can be greatly improved if secondary phases are used. This gain is a combined effect of an improved range of take-off angles and the use of differential traveltimes between first and secondary arriving phases. Our results also show that reliable information on the Moho depth is crucial to obtain accurate focal depths, if Pn or PmP phases are used in the relocation process. Finally, our approach demonstrates that proper identification of the main crustal phases in combination with an appropriate model parametrization in the forward solver will significantly improve earthquake location

    Protonentherapie mit "Spot-Scanning" bei Rhabdomyosarkomen im frühen Kindesalter: Erste Erfahrungen am PSI

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    Ziel:: Die Durchführbarkeit und Verträglichkeit der Spot-Scanning-Protonentherapie in tiefer Sedierung bei Kindern mit Rhabdomyosarkomen (RMS) sollten geprüft werden. Patienten und Methodik:: Seit 2004 werden junge Kinder am Paul Scherrer Institut (PSI), Villigen, Schweiz, auch in tiefer Sedierung mit Protonen bestrahlt. Ausgewertet wurden Kinder unter 5 Jahren mit RMS im Bereich des Kopfes und Körperstamms. Alle Kinder waren in eine Therapieoptimierungsstudie eingeschlossen und wurden prospektiv hinsichtlich der Verträglichkeit der Bestrahlung untersucht. Ergebnisse:: Neun Kinder im medianen Alter von 1,9 Jahren wurden untersucht (sechs embryonale RMS und je ein alveoläres, undifferenziertes und nicht klassifizierbares RMS). Die Lokalisationen waren parameningeal (n = 4), orbital (n = 3), Kopf-Hals-Bereich (n = 1) und Prostata (n = 1). Bei allen Kindern lag ein IRS-Stadium III vor. Die Bestrahlung erfolgte ausschließlich mit Protonen (Gesamtdosen 46-54 CGE [Cobalt-Gray-Äquivalent]). Akuttoxizitäten Grad 3 oder 4 nach RTOG/EORTC traten ausschließlich im Bereich des Knochenmarks auf. Schlussfolgerung:: Die Protonentherapie bei RMS im frühen Kindesalter war problemlos durchführbar und hervorragend verträglich. Prospektive, standardisierte Erhebungen von Spättoxizität und Lebensqualität sind essentiel

    Management of post-mining large-scale ground failures : blast swarms field experiment for calibration of permanent microseismic early-warning systems

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    International audienceIn France, decades of coal and iron-ore mining have left extensive underground cavities beneath or in the vicinity of urban areas. This poses an environmental challenge for society. To ensure post-mining risk management and public safety, wherever remediation is not possible, numerous real-time microseismic monitoring systems are being installed. The objective is to detect remote rock mass fracturing processes, precursory events and acceleration phases for appropriate and timely action. Although no consistent collapse has occurred in any of the monitored areas yet, single 3-D probes record many microseismic events of very low amplitude which create difficulties in the quantitative data analysis. The development of specific quantitative processing has therefore become a major issue in our research work. For that purpose, a field experiment was carried out on six of the instrumented sites. It consisted of sequences of small blasts in mine pillars which were accurately controlled in terms of the location, orientation and energy of the explosive source. The data analysis was used to calibrate parameters (velocity model, 3-D sensor orientation, etc.) for reliable 3-D localization and to develop an empirical law to estimate the source energy from the sensor energy. This work now enables us to analyze real microseismic events with a considerably better level of accuracy and to obtain enough information and confidence to discuss these data in terms of site stability
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