A suitable combination of magnetic field determinations is assembled in the whole area of the Jalisco block in central-western Mexico; it serves as the basis for calculations of the Curie Point Isotherm by means of Spectral Analysis. The Jalisco block contains numerous volcanic manifestations; an attempt is made at correlating the Curie Isotherm (CI) with volcanic manifestations and its implicit risk to nearby populated regions. A preliminary analysis of this isotherm is carried out using areas of 60 × 60 km2, where the volcanic regions at the NW and SE portions of the Tepic-Zacoalco (T-Z) rift coincide with shallow layers of the CI. Results show an unexpected region in the middle of the T-Z rift, where the isotherm deepens to 12 km depth and volcanism appears to be missing. The authors argue that this phenomenon may be associated with a flare up episode occurring at 5-3 Ma along the rift. Varying the area used for the calculation of the CI, from 30 × 30 km2 to 120 × 120 km2, illustrates how the concomitant changes in volume affect the depth of penetration. The authors find exceptional regions in which the CI shows shallow depths at all area sizes used in the calculations; this consistency is interpreted as a magnetic alteration of the crust originating at mid-crustal depths. These regions also correspond to high values of the Bouguer anomaly reported elsewhere. Six magneto-stratigraphic profiles are presented for the results of the 60 × 60 km2 calculations, where geologic, topographic, and magnetic properties are displayed along their length.
{"title":"Volcanism and Curie Isotherm Distribution in the Jalisco Block, Mexico","authors":"R. Alvarez, Vladimir Palafox","doi":"10.54963/ptnd.v1i1.37","DOIUrl":"https://doi.org/10.54963/ptnd.v1i1.37","url":null,"abstract":" A suitable combination of magnetic field determinations is assembled in the whole area of the Jalisco block in central-western Mexico; it serves as the basis for calculations of the Curie Point Isotherm by means of Spectral Analysis. The Jalisco block contains numerous volcanic manifestations; an attempt is made at correlating the Curie Isotherm (CI) with volcanic manifestations and its implicit risk to nearby populated regions. A preliminary analysis of this isotherm is carried out using areas of 60 × 60 km2, where the volcanic regions at the NW and SE portions of the Tepic-Zacoalco (T-Z) rift coincide with shallow layers of the CI. Results show an unexpected region in the middle of the T-Z rift, where the isotherm deepens to 12 km depth and volcanism appears to be missing. The authors argue that this phenomenon may be associated with a flare up episode occurring at 5-3 Ma along the rift. Varying the area used for the calculation of the CI, from 30 × 30 km2 to 120 × 120 km2, illustrates how the concomitant changes in volume affect the depth of penetration. The authors find exceptional regions in which the CI shows shallow depths at all area sizes used in the calculations; this consistency is interpreted as a magnetic alteration of the crust originating at mid-crustal depths. These regions also correspond to high values of the Bouguer anomaly reported elsewhere. Six magneto-stratigraphic profiles are presented for the results of the 60 × 60 km2 calculations, where geologic, topographic, and magnetic properties are displayed along their length.","PeriodicalId":325067,"journal":{"name":"Prevention and Treatment of Natural Disasters","volume":"57 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130116746","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}
A numerical procedure, based on an evolutionary optimization algorithm, has been proposed by the authorsfor the simultaneous generation of the three components of the seismic ground acceleration. The methodology allowsthe determination of a train of seismic waves modeled by three different waveforms, for the generation of groundseismic acceleration components. The parameters of each wave, i.e., amplitude, frequency, duration, arrival time anddirection, are determined using an evolutionary optimization algorithm. Although no theoretical justification is knownby the authors for the generation, at the seismic source, of specific initial waveforms, both in case of fracture or ofsliding with friction, waveform acceleration components that satisfy the condition of zero final velocity should inprinciple be preferred. The latter is a physical restriction that is automatically satisfied by anti-symmetrical functions,thus eliminating the need to correct the baseline of simulated accelerograms. The error of fit of simulated accelerogramsgenerated by three different waveforms proposed in the literature was herein determined by comparison with actualseismic records. On that basis, estimations of the expected error of the evolutionary optimization algorithm inengineering applications are presented.
{"title":"On the Selection of Wavelet Models in the Simulation of Seismic Accelerograms through Evolutionary Optimization","authors":"Daniela Dalla Chiesa, L. Miguel, J. D. Riera","doi":"10.54963/ptnd.v1i1.19","DOIUrl":"https://doi.org/10.54963/ptnd.v1i1.19","url":null,"abstract":"A numerical procedure, based on an evolutionary optimization algorithm, has been proposed by the authorsfor the simultaneous generation of the three components of the seismic ground acceleration. The methodology allowsthe determination of a train of seismic waves modeled by three different waveforms, for the generation of groundseismic acceleration components. The parameters of each wave, i.e., amplitude, frequency, duration, arrival time anddirection, are determined using an evolutionary optimization algorithm. Although no theoretical justification is knownby the authors for the generation, at the seismic source, of specific initial waveforms, both in case of fracture or ofsliding with friction, waveform acceleration components that satisfy the condition of zero final velocity should inprinciple be preferred. The latter is a physical restriction that is automatically satisfied by anti-symmetrical functions,thus eliminating the need to correct the baseline of simulated accelerograms. The error of fit of simulated accelerogramsgenerated by three different waveforms proposed in the literature was herein determined by comparison with actualseismic records. On that basis, estimations of the expected error of the evolutionary optimization algorithm inengineering applications are presented.","PeriodicalId":325067,"journal":{"name":"Prevention and Treatment of Natural Disasters","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128922364","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}
R. Sharbati, H. Amindavar, H. Ramazi, S. Foti, B. Farzanegan
This article proposes a stochastic model for generation of synthetic seismic ground motions. In the first step, the wavelet coefficients of a record are extracted by the dual-tree complex discrete wavelet transform (DT-CDWT) and then they are simulated by an optimized Cauchy-Gaussian blend (CGB) model. This model predicts well the energy distribution of seismic ground motions, because in this model, the Gaussian distribution simulates smooth peaks and the Cauchy distribution is used to simulate impulsive peaks. Also, this model simulates several ascending-descending cycles in the time domain, predicts multiple frequency peaks each time, and simulates sequence-type records.
{"title":"Optimized Cauchy-Gaussian Blend Model for Stochastic-Parametric Simulation of Seismic Ground Motions","authors":"R. Sharbati, H. Amindavar, H. Ramazi, S. Foti, B. Farzanegan","doi":"10.54963/ptnd.v1i1.62","DOIUrl":"https://doi.org/10.54963/ptnd.v1i1.62","url":null,"abstract":"This article proposes a stochastic model for generation of synthetic seismic ground motions. In the first step, the wavelet coefficients of a record are extracted by the dual-tree complex discrete wavelet transform (DT-CDWT) and then they are simulated by an optimized Cauchy-Gaussian blend (CGB) model. This model predicts well the energy distribution of seismic ground motions, because in this model, the Gaussian distribution simulates smooth peaks and the Cauchy distribution is used to simulate impulsive peaks. Also, this model simulates several ascending-descending cycles in the time domain, predicts multiple frequency peaks each time, and simulates sequence-type records. ","PeriodicalId":325067,"journal":{"name":"Prevention and Treatment of Natural Disasters","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126117008","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}
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