{"title":"Low-Frequency Electromagnetic Signals Observed before Strong Earthquakes","authors":"I. Rokityansky, V. Babak, A. Tereshyn","doi":"10.5772/intechopen.88522","DOIUrl":"https://doi.org/10.5772/intechopen.88522","url":null,"abstract":"We consider two kinds of signals preceding earthquake (EQ): intensification of internal electromagnetic (EM) field – lithosphere emission (LE) and change of the Earth interior response function (RF). Several cases of LE before strong EQs were reviewed and analyzed, and preliminary portrait of LE precursor was compiled. LE can appear several times with lead time month(s), weeks, days, and hours and can attain amplitude of several hundreds of nT which not uniformly decreases with increasing distance from the source. Typical LE frequency content/maximum is 0.01–0.5 Hz. Data of 19 Japanese geomagnetic observatories for 20 years preceding the Tohoku EQ on March 11, 2011 were analyzed, and RFs (mainly induction vector) were calculated. At six observatories in 2008–2010, anomalous variations of RF were separated which can be identified as middle-term precursors. Applying the original method developed in Ukraine, a short-term two-month-long precursor of bay-like form was separated by phase data of observatory KNZ in the Boso peninsula where electrical conductivity anomaly was also discovered. Hypothetical explanation based on tectonic data is advanced: Boso anomaly connects two large-scale conductors—Pacific seawater and deep magma reservoir beneath a volcanic belt. Between two so different conductors, an unstable transition zone sensitive to changes of stress before strong EQs can be expected.","PeriodicalId":301313,"journal":{"name":"Seismic Waves - Probing Earth System","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130895050","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Cylindrical Surface Wave: Revisiting the Classical Biot’s Problem","authors":"J. Rushchitsky","doi":"10.5772/intechopen.86910","DOIUrl":"https://doi.org/10.5772/intechopen.86910","url":null,"abstract":"The problem on a surface harmonic elastic wave propagating along the free surface of cylindrical cavity in the direction of cavity axis is considered. In the case of isotropic medium, this is the classical Biot ’ s problem of 1952. First, the Biot pioneer work is revisited: the analytical part of Biot ’ s findings is shown in the main fragments. The features are using two potentials and representation of solution by Macdonald functions of different indexes. Then the new direct generalization of Biot ’ s problem on the case of transversely isotropic medium within the framework of linear theory of elasticity is proposed. Transition to the transverse isotropy needs some novelty — necessity of using the more complex representations of displacements through two potentials. Finally, a generalization of Biot ’ s problem on the case of isotropic and transversely isotropic media in the framework of linearized theory of elasticity with allowance for initial stresses is stated. This part repeats briefly the results of A.N. Guz with co-authors of 1974. The main features are using the linearized theory of elasticity and one only potential. All three parts are shown as analytical study up to the level when the numerical methods have to be used.","PeriodicalId":301313,"journal":{"name":"Seismic Waves - Probing Earth System","volume":"32 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114760182","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Efficient Simulation of Fluids","authors":"P. Gac, Emmanuelle Darles, P. Louis, L. Aveneau","doi":"10.5772/INTECHOPEN.86619","DOIUrl":"https://doi.org/10.5772/INTECHOPEN.86619","url":null,"abstract":"Fluid simulation is based on Navier-Stokes equations. Efficient simulation codes may rely on the smooth particle hydrodynamic toolbox (SPH), a method that uses kernel density estimation. Many variants of SPH have been proposed to optimize the simulation, like implicit incompressible SPH (IISPH) or predictive-corrective incompressible SPH (PC-ISPH). This chapter recalls the formulation of SPH and focuses on its effective parallel implementation using the Nvidia common unified device architecture (CUDA), while message passing interface (MPI) is another option. The key to effective implementation is a dedicated accelerating structure, and therefore some well-chosen parallel design patterns are detailed. Using a rough model of the ocean, this type of simulation can be used directly to simulate a tsunami resulting from an underwater earthquake.","PeriodicalId":301313,"journal":{"name":"Seismic Waves - Probing Earth System","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121178427","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"A High-Order Finite Volume Method for 3D Elastic Modelling on Unstructured Meshes","authors":"Wensheng Zhang","doi":"10.5772/INTECHOPEN.86400","DOIUrl":"https://doi.org/10.5772/INTECHOPEN.86400","url":null,"abstract":"In this chapter, a new efficient high-order finite volume method for 3D elastic modelling on unstructured meshes is developed. The stencil for the high-order polynomial reconstruction is generated by subdividing the relative coarse tetrahedrons. The reconstruction on the stencil is performed by using cell-averaged quantities represented by the hierarchical orthonormal basis functions. Unlike the traditional high-order finite volume method, the new method has a very local property like the discontinuous Galerkin method. Furthermore, it can be written as an inner-split computational scheme which is beneficial to reducing computational amount. The reconstruction matrix is invertible and remains unchanged for all tetrahedrons, and thus it can be pre-computed and stored before time evolution. These special advantages facilitate the parallelization and high-order computations. The high-order accuracy in time is obtained by the Runge-Kutta method. Numerical computations including a 3D real model with complex topography demonstrate the effectiveness and good adaptability to complex topography.","PeriodicalId":301313,"journal":{"name":"Seismic Waves - Probing Earth System","volume":"53 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124831562","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
京公网安备 11010802042870号
求助内容：
应助结果提醒方式：