1,720,959 research outputs found
Replication Data for: Premus et al. (2022) Bridging time scales of faulting: from coseismic to postseismic slip of the Mw 6.0 2014 South Napa, California earthquake
No full textDate: 24. 6. 2022
Author: Jan Premus, Department of Geophysics, Charles University, Prague, email: [email protected]
This dataset contains a database (samples.dat) of forward models obtained from the dynamic inversion of the Mw 6.0 2014 South Napa, California earthquake (See INFO.txt file for more information).
Dataset was used in a paper: Premus, J., F. Gallovic, and J.-P. Ampuero (2022). Bridging time scales of faulting: from coseismic to postseismic slip of the Mw 6.0 2014 South Napa, California earthquake. Sci. Adv. (In review)
Vývoj efektivního kódu pro dynamické simulace zemětřesení
Full text linkTitle: Development of effective code for earthquake dynamic source simulations Author: Bc. Jan Premus Department: Department of Geophysics Supervisor: doc. RNDr. František Gallovič, Ph.D, Department of Geophysics Abstract: Dynamic rupture modeling coupled with strong motion data fitting offers an insight into physical mechanisms behind earthquake sources [Gallovic et al., 2019]. Running a large number of dynamic model simulations is required due to the nonlinearity of the inverse problem. The goal of this Thesis is a development of an efficient forward solver for the dynamic inversions. The fi- nite difference staggered grid code FD3D by Madariaga and Olsen [1998] served as a basis for the development, offering sufficient speed, but rather low accu- racy. Traction at split node implementation of the fault boundary condition and perfectly matched layers as the absorbing boundary condition were required to obtain desirable accuracy. In addition to the slip weakening friction law, fast ve- locity weakening friction law has been implemented, increasing the applicability of the code. We test the new code FD3D TSN using USGS/SCEC benchmarks TPV5 (slip-weakening friction) and TPV104 (fast rate weakening friction) [Harris et al., 2018], showing very good agreement with results calculated by advanced numerical...Název: Vývoj efektivního kódu pro dynamické simulace zemětřesení Autor: Bc. Jan Premus Katedra: Katedra geofyziky Vedoucí práce: doc. RNDr. František Gallovič, Ph.D, Katedra geofyziky Abstrakt: Dynamické modelování trhliny ve spojení s s vystižením silných pohybů umožňuje získat vhled do fyzikálních mechanismů kontrolujících zdroj zemětřesení [Gallovič a kol., 2019]. Nelinearita inverzního problému vyžaduje spouštění velkého množství simulací. Cílem této diplomové práce je vývoj efek- tivního kódu pro řešení inverzní úlohy. Původní kód FD3D od autorů Madariagy a Olsena [1998], používající konečné difference s posunutými sítěmi, nabízel dostatečnou rychlost, ale ne přesnost. Byl použit jako základ pro další vývoj. Implementace okrajové podmínky na zlomu metodou trakce v půleném uzlu (traction at split node) a absorbční podmínky pomocí metody perfektně sladěných vrstev (per- fectly matched layers) bylo třeba k získání požadované přesnosti. Jako mod- erní alternativa ke skluzem slábnoucímu (slip weakening) zákonu tření byl im- plementován s rychlostí rychle slábnoucí (fast velocity weakening) zákon, což dále rozšířilo škálu jevů, které je možné modelovat. Nový kód FD3D TSN byl otestován pomocí...Department of GeophysicsKatedra geofyzikyFaculty of Mathematics and PhysicsMatematicko-fyzikální fakult
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Development of effective code for earthquake dynamic source simulations
No full textTitle: Development of effective code for earthquake dynamic source simulations Author: Bc. Jan Premus Department: Department of Geophysics Supervisor: doc. RNDr. František Gallovič, Ph.D, Department of Geophysics Abstract: Dynamic rupture modeling coupled with strong motion data fitting offers an insight into physical mechanisms behind earthquake sources [Gallovic et al., 2019]. Running a large number of dynamic model simulations is required due to the nonlinearity of the inverse problem. The goal of this Thesis is a development of an efficient forward solver for the dynamic inversions. The fi- nite difference staggered grid code FD3D by Madariaga and Olsen [1998] served as a basis for the development, offering sufficient speed, but rather low accu- racy. Traction at split node implementation of the fault boundary condition and perfectly matched layers as the absorbing boundary condition were required to obtain desirable accuracy. In addition to the slip weakening friction law, fast ve- locity weakening friction law has been implemented, increasing the applicability of the code. We test the new code FD3D TSN using USGS/SCEC benchmarks TPV5 (slip-weakening friction) and TPV104 (fast rate weakening friction) [Harris et al., 2018], showing very good agreement with results calculated by advanced numerical..
Joint inverse modeling of coseismic and postseismic slip of the 2014 South Napa, California, earthquake
No full textTitle: Joint inverse modeling of coseismic and postseismic slip of the 2014 South Napa, California, earthquake Author: Jan Premus Department: Department of Geophysics Supervisor: prof. František Gallovič, Department of Geophysics Abstract: Slip at tectonic faults spans a wide range of time scales, from tens of seconds of earthquake coseismic rupture to months of aseismic afterslip, recorded in seismograms and geodetic data. The two slip phenomena are often studied separately, focusing on kinematic aspects. We introduce a Bayesian method for physics-based joint inverse modeling of an earthquake slip and afterslip, employ- ing a unifying rate-and-state friction law. To simulate the rupture propagation, we develop an efficient finite-difference open-source code FD3D TSN. GPU ac- celeration of the code yields speed-up by a factor of 10 with respect to a CPU, enabling hundreds of thousands of earthquake simulations in a reasonable time. We also implement a quasi-dynamic afterslip simulation using a boundary inte- gral element method. We apply the Bayesian dynamic inversion to the 2014 Mw 6.0 Napa earthquake. We reveal the dynamics of coseismic and postseismic slip in terms of stress and friction in a unified model, reconciling previous disjunctive analyses of the event. We show that the two types of slip are mostly..
Inverse physics-based modeling of the 2016 Mw 6.1 Tottori earthquake
No full textInverse physics-based modeling of the 2016 Mw 6.1 Tottori earthquake The 2016 Mw 6.2 left-lateral strike-slip Tottori earthquake occurred in the central part of the Tottori Prefecture in the Chugoku region in western Japan. Published rupture models inferred either from geodetic or seismic data exhibit significant discrepancies. In this study, we perform a so-far missing dynamic rupture simulation to improve the understanding of the event. We utilize the 3D finite-difference staggered grid code FD3D\_TSN to simulate the dynamic rupture propagation assuming the classic linear slip-weakening friction law on a planar vertical fault. Synthetic seismograms are calculated using the representation theorem by convolving the obtained slip rates with Green's functions precalculated in 1D velocity models acquired for each station from a 3D model. We utilize the fd3d_tsn_pt code to perform a dynamic source inversion with spatially variable prestress and friction parameters, formulated in a Bayesian framework, employing the Parallel Tempering MCMC approach to sample the posterior distribution of the model parameters. We use local low-frequency seismic waveforms (up to 0.6-1.2 Hz) and GNSS static coseismic displacements. We obtain posterior model samples with complex rupture propagation, discuss the inferred heterogeneous..
Simulation of the 2016 Tottori (Mw 6.1) earthquake using a dynamic source model
No full textWe perform a parametric study for simple elliptical dynamic models of rupture propa- gation. We simulate the earthquake from the central part of Japanese prefecture Tottori in 2016 using a code for a simulation of the rupture propagation developed at the Depart- ment of Geophysics assuming the classic linear slip-weakening friction law. We evaluate the match of synthetic seismograms with the observed data. From different models we choose the one best fitting the data. The values of seismic moment, slip distribution, stress drop, radiated energy and radiation efficiency are close to the ones from published articles. In conclusion we point out some possible sources of inaccuracies in modelling and suggest improvements for the future.
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
- …
