Seismic Radiation From Simple Models of Earthquakes

We review some basic features of shear wave generation and energy balance for a 2D anti plane rupture. We first study the energy balance for a flat fault, and for a fault that contains a single localized kink. We determine an exact expression for the partition between strain energy flow released from the elastic medium surrounding the fault, radiated energy flow and energy release rate. This balance depends only on the rupture speed and the residual stress intensity factor. When the fault contains a kink, the energy available for fracture is reduced so that the rupture speed is reduced. When rupture speed changes abruptly, the radiated energy flow also changes abruptly. As rupture propagates across the kink, a shear wave is emitted that has a displacement spectral content that decreases like ω^(-2) at high frequencies. We then use spectral elements to model the propagation of an antiplane crack with a slip-weakening friction law. Since the rupture front in this case has a finite length scale, the wave emitted by the kink is smoothed at very high frequencies but its general behavior is similar to that predicted by the simple sharp crack model. A model of a crack that has several kinks and wanders around a mean rupture directions, shows that kinks reduce the rupture speed along the average rupture direction of the fault. Contrary to flat fault models, a fault with kinks produces high frequency waves that are emitted every time the rupture front turns at a kink. Finally, we discuss the applicability of the present results to a 3D rupture model

Hopf algebras with triality

In this paper we revisit and extend the constructions of Glauberman and Doro on groups with triality and Moufang loops to Hopf algebras. We prove that the universal enveloping algebra of any Lie algebra with triality is a Hopf algebra with triality. This allows us to give a new construction of the universal enveloping algebras of Malcev algebras. Our work relies on the approach of Grishkov and Zavarnitsine to groups with triality.Comment: AMS-LaTeX, 23 pages. To appear in Trans. Amer. Math. So

Study of the fracture process of Al Hoceima earthquake (24/02/2004, Mw=6.2) from regional and teleseismic data.

We studied the source time function (STF) and rupture process of the 2004 Alhoceima, Morocco earthquake of Mw = 6.2 using teleseismic and regional broad-band data. From regional broad-band data, STF function was determined using three large after- shocks as empirical Green functions. We inverted of body wave forms at teleseismic distances using an extended source model with rupture velocity between 2.5-3.0 km and using as preliminary orientation the fault plane solution derived from 126 P-wave polarities. Results show a complex bilateral rupture formed by four shallow subevents (2-8 km) with a maximum seismic moment release during the first seconds (more than 80% of a total of 1.8x1018 Nm) and time duration of 8-10 s. The focal mechanism shows a strike slip motion with a normal component. Nodal planes strike on NNE- SSW and WNW-ESE direction with horizontal pressure axes in NNW-SSE direction. The rupture propagated mainly towards the North. This propagation is in agreement with the damages caused in the epicentral region. The larger aftershocks have been relocated using a master event method. Comparisson of these results with those ob- tained for the 1994 earthquake shown similar behaviour: complex rupture process and, apparently, no relation of the 1994 nor the 2004 shocks with the Nekor fault, the most important geological feature in the area. The stress pattern derived from focal mech- anisms of 1994 and 2004 are in agreement with the regional stress pattern, horizontal compression in NNW-SSE and horizontal extension in E-W direction in the Alboran Sea

Understanding Policy Change through Bricolage: The Case of Chile's Renewable Energy Policy

Chile is a country where path dependency made energy policy change extremely difficult by international standards. However, the country has recently become a renewable energy poster child thanks to a gradual process of policy change. How was this possible? This article contributes to discussions about policy change driven by ideas and to explaining the puzzling case of Chilean energy policy change. It does so by discussing the mechanism of bricolage—the recombination of old and new ideas by policy entrepreneurs—and its capacity to produce policy change in contexts of high path dependency. The article develops the political manifestations and consequences of bricolage and problematizes how actors continue to contest and change ideas' meaning after they have been institutionalized, a key question when analyzing processes of bricolage. The analysis is based on an array of data sources including interviews with key actors, newspaper notes, and legislative proceedings.1 Introduction 2 Literature review 3 Chile: A least-likely case of energy policy change 4 Methods, data, and analysis 5 Results: Explaining the change in Chilean energy policy 6 Conclusions and discussion Acknowledgements Appendix A Reference

Method for the Calculation of DPA in the Reactor Pressure Vessel of Atucha II

One of the limiting factors of the life of a nuclear power plant (NPP) is the state of the reactor pressure vessel (RPV). Embrittlement is the most important effect affecting RPV aging. The irradiation with neutrons, especially fast neutrons, is the primary cause of this embrittlement. NPP safe operation requires to ensure RPV integrity over its lifetime, threatened by the neutron radiation-induced embrittlement. In this paper, we identify the areas where the RPV neutron radiation is maximum and perform calculations of the displacement-per-atom (DPA) rate in those areas using the MCNP5 code. It was determined that the maximum DPA rate in the RPV wall with fresh fuel element (FE) is 3.76(3) × 10-12 s-1, it takes place in front of FEs BA42 and BL43, and it is symmetrical about the central channel, LG04, and LH03

Calculando la vejez: Gestión previsional en trabajadores/as de bajos ingresos

The Chilean pension system is a milestone regarding the institutionalization of individual responsibility and individual decisions as determinant of the pension performance. Few assessments have been made, however, to how people make decisions in this system. From a qualitative study, the following article explores how low-income workers living in Santiago make their pension decisions. Using recent perspectives in economic sociology, the article provides a dynamic interpretation of the possibilities of social agency in a complex and novel scenario, focusing on the construction of calculability frameworks that permit to make decisions and the structural and institutional elements that condition them. The last ones overflow the constructed frameworks and make necessary reframing processes through which the pension management intermingles with strategies for the generation of current incomes.El sistema de pensiones chileno constituye un hito en cuanto a la institucionalización de la responsabilidad individual y las decisiones individuales como determinante del desempeño previsional. Pocas evaluaciones se han realizado, sin embargo, a la manera como las personas toman sus decisiones en este sistema. a partir de un estudio cualitativo, el siguiente artículo explora cómo trabajadores/as de bajos ingresos de la ciudad de Santiago toman sus decisiones previsionales. Utilizando perspectivas recientes dentro de la sociología económica, el artículo ofrece una interpretación dinámica de las posibilidades de agencia en un escenario social complejo y novedoso, con foco en la construcción de marcos de calculabilidad que permiten tomar decisiones, y los elementos estructurales e institucionales que los condicionan. Estos últimos desbordan los marcos construidos y hacen necesarios procesos de re-encuadre por medio de los cuales la gestión previsional se entremezcla con estrategias para la generación de ingresos actuales

Frequency‐Dependent Moment Tensors of Induced Microearthquakes

Analysis of 984 induced microearthquakes from The Geysers geothermal reservoir in California reveals that the retrieved moment tensors depend on the frequency band of the inverted waveforms. The observed dependence is more significant for the percentages of the double‐couple, compensated linear vector dipole, and isotropic (ISO) components than for the focal mechanisms. The average root‐mean‐square of the moment tensors obtained in different frequency bands is correlated with spectra of ambient noise. The percentages of double‐couple and ISO components tend to decrease and increase with the upper cutoff frequency (fu), respectively. This suggests that shear rupture radiates energy preferentially in a lower frequency band and tensile rupture in a higher frequency band. Events displaying a strong increase of the ISO with fu are confined within the same depth interval as the injection points. This might be related to the strong thermoelastic effects in the vicinity of injection points that promote opening of small cracks adjacent to the main fractures