Download or read book WAVEFORM AND GEODYNAMIC MODELING OF SEISMICITY ASSOCIATED WITH THE CHARLEVOIX SEISMIC ZONE written by Oluwaseun Idowu Fadugba and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Charlevoix seismic zone (CSZ) is the most seismically active region in eastern Canada. It is located within the Late Proterozoic-Early Cambrian St. Lawrence rift zone in southeastern Quebec. The location was also the site of a Devonian impact crater. The CSZ poses a high seismic risks due to its seismicity compared to the other seismic zones in the area and its proximity to densely populated cities (e.g., Quebec City, Ottawa, and Montreal). It is also responsible for much of the seismic hazard in New England. Previous studies in the CSZ observed a maximum compressive stress orientation of N86, which represents a 32 clockwise rotation from the regional orientation determined from nearby boreholes (i.e., 54). Dividing the CSZ into two clusters, one northwest of the SLF and one to the southeast. The stress inversion for earthquakes in the NW cluster) and for earthquakes in the SE cluster yielded orientations of N55 and N101, respectively. Previous studies also suggest two sets of geometries for the rift faults. One set has a uniform dip of 70SE for all three faults while the other has 65, 40, and 40SE, from north to south, respectively. My research focuseson the waveform and geodynamic modeling of seismicity associated with the CSZ by examining the characteristics of the earthquakes usingfocal mechanisms and wave propagation, stress inversion, clustering analyses and numerical models. Firstly, the seismological information offers an important database to be examined with geodynamic modeling, using PyLith, to investigate the combined effects of the preexisting structures and regional stresses on earthquake activity and stress rotations in the CSZ. We conclude that the CSZ seismicity is due to the combined effects of the rift faults and the impact structure and that the planar faults we considered in the model can explain the observed seismicity but not the stress rotations. We also conclude that an impact structure 4 times less elastically stiff than the surrounding crust can explain the seismicity in the CSZ. Secondly, part of my research involves determining focal mechanisms ofrelocated earthquakesin the CSZ with M 2 usingwave polarities and amplitude. I perform stress inversion using the new focal mechanisms and investigate the change in maximum stress orientation laterally and with depth. Stress inversion using all focal mechanisms shows that the orientation is N103, in contrast to N86 from previous work, with reverse faulting dominating. We observed a orientation of N73 within the impact zone compared to N106 outside the zone. A distinct systematic clockwise change in orientation of 44 is observed as a function of source depth from the surface to 20 km, changing from N83 to N127. We suggest that seismicity and the observed stress rotations of the CSZ are controlled by velocity heterogeneity and rock stiffness, including the impact structure, and pre-existing fault structure within a stress field generated by both plate tectonic forces and glacial rebound. Lastly, this study also uses clustering analyses of earthquake locations to constrain the geometry of the rift fault better using a modifiedversion of the Optimal Anisotropic Dynamic Clustering (OADC) algorithm. Our fault model shows dips of 65, 39 and 47 for the three fault system in the CSZ near the impact but changes to a 65-69-64 dipping fault geometry in the NE end of the CSZ. Our model also shows the geometry of some bounding faults associated with the damage zone of the impact structure. This study presents a realistic but simplified fault geometry of the CSZ and suggests a combination of the type of the two fault geometries found in previous studies..
Download or read book New 1 D and 3 D Velocity Models and Hypocenter Relocations for the Charlevoix Seismic Zone written by Sara Kelemencky and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We present new 1-D and 3-D P- and S-wave velocity models for the active Charlevoix seismic zone (CSZ). The CSZ has generated several damaging earthquakes but the causative reason for the seismic activity in this intraplate region is unknown. Structure developed during prior tectonic events could be influencing present day seismic activity. Previous velocity models derived from local earthquake tomography utilize an overly simplistic half-space starting model. We develop improved 1-D P- and S-wave starting models using VELEST. These models contain several layers in the depth range 0 to 30 km and provide better starting models for 3-D inversion. Our new 3-D P- and S-wave velocity models contain several interesting anomalies that will provide insight into what factors influence earthquake occurrence in the CSZ. Relocated hypocenters outline the spatial extent of currently microseismically active seismogenic faults.
Download or read book Double difference Earthquake Relocation of Charlevoix Seismicity Eastern Canada and Implication for Regional Geological Structures written by Meng Pang and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "Eastern Canada is located within the North American Plate and, therefore, should have a relatively low rate of earthquake activity compared with interplate boundary. However, large earthquakes do occur in the region, especially in the Charlevoix Seismic Zone (CSZ) located about 100km downstream from Quebec City. In history, the Charlevoix Seismic Zone has been subject to five earthquakes with magnitude 6 or larger (M~7 in 1663; M~6 in 1791 and 1860; M~6.5 in 1870; MS 6.2 +_0.3 in 1925). However, the regional geological structures of the CSZ are not well understood. As one of the most seismically active region in Eastern Canada, the earthquakes in the CSZ are a significant hazard. Therefore, improved knowledge of distribution and seismic characteristics of these events provides a great benefit for understanding the seismic hazard of the CSZ. In this thesis, I apply earthquake location technique on discovering fault features in CSZ. Earthquake location, as a basic technique in seismometry, plays an important role in the studying of fault structures. The double-difference earthquake location algorithm (HYPODD) is able to get high-resolution hypocenter locations by introducing the residual between observed and calculated travel times between two events, and removing the effects of the un-modeled velocity structure. In this thesis, the resolution of double-difference location algorithm was analyzed using the seismic data of Canadian National Seismograph Network(CNSN) from Jan,1988 to Oct, 2010. The double-difference earthquake location algorithm was used to relocate more than 400 earthquakes in the Charlevoix seismic zone (CSZ), using a layered velocity model. The location results of initial catalog data and double-difference relocation results visually compare with each other, and the cross section of the northeast part in CSZ shows two nearly parallel faults dipping about 60 degree to the southeast. This provides evidence that there are minor rifting geological features underneath the St-Laurence River." --
Download or read book Full Seismic Waveform Modelling and Inversion written by Andreas Fichtner and published by Springer Science & Business Media. This book was released on 2010-11-16 with total page 352 pages. Available in PDF, EPUB and Kindle. Book excerpt: Recent progress in numerical methods and computer science allows us today to simulate the propagation of seismic waves through realistically heterogeneous Earth models with unprecedented accuracy. Full waveform tomography is a tomographic technique that takes advantage of numerical solutions of the elastic wave equation. The accuracy of the numerical solutions and the exploitation of complete waveform information result in tomographic images that are both more realistic and better resolved. This book develops and describes state of the art methodologies covering all aspects of full waveform tomography including methods for the numerical solution of the elastic wave equation, the adjoint method, the design of objective functionals and optimisation schemes. It provides a variety of case studies on all scales from local to global based on a large number of examples involving real data. It is a comprehensive reference on full waveform tomography for advanced students, researchers and professionals.
Download or read book Investigation of the Space time Distribution of Earthquakes in the Charlevoix Seismic Zone Quebec written by Mariana Eneva and published by . This book was released on 1994 with total page 154 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Intraplate Earthquakes written by Pradeep Talwani and published by Cambridge University Press. This book was released on 2014-04-24 with total page 351 pages. Available in PDF, EPUB and Kindle. Book excerpt: Intraplate earthquakes occur away from tectonic plate boundaries: their locations are difficult to predict, risking huge damage and loss of life. The 2001 Bhuj earthquake (featured in this book) was the largest intraplate earthquake for three decades and has provided unique insight into these events. This cutting-edge book brings together research from international leading experts in the field. Each chapter provides a comprehensive review of these earthquakes in a different global location, ranging from Australia, China, India and the Sea of Japan, to Western Europe, Brazil, New Madrid (Central USA), and Eastern Canada. They explore similarities and differences between regional features and the mechanical models required to explain them, as well as assessing geophysical techniques used to investigate them. Providing the first global overview of intraplate earthquakes, this is an essential book for academic researchers and professionals in seismology, tectonics, tectonophysics, geodesy, structural geology, earthquake dynamics, geophysics, and structural engineering.
Download or read book Continental Intraplate Earthquakes written by Seth Stein and published by Geological Society of America. This book was released on 2007-01-01 with total page 412 pages. Available in PDF, EPUB and Kindle. Book excerpt: "This volume brings together a sampling of research addressing issues of continental intraplate earthquakes, including a core of papers from special sessions held at the spring 2004 Joint Assembly of the American and Canadian Geophysical Unions in Montreal. Papers address the broad related topics of the science, hazard, and policy issues of large continental intraplate earthquakes in a worldwide context. One group of papers addresses aspects of the primary scientific issue--where are these earthquakes and what causes them? Answering this question is crucial to determining whether they will continue there or migrate elsewhere. A second group of papers addresses the challenge of assessing the hazard posed by intraplate earthquakes. Although it may be a very long time before the scientific issues are resolved, the progress being made is helping attempts to estimate the probability, size, and shaking of future earthquakes, and the uncertainty of the results. A third group of papers explores the question of how society should mitigate the possible effects of future large continental intraplate earthquakes. Communities around the world face the challenge of deciding how to address this rare, but real, hazard, given the wide range of other societal needs. Continental intraplate earthquakes will remain a challenge to seismologists, earthquake engineers, policy makers, and the public for years to come, but significant progress toward understanding and addressing this challenge is now being made."--Publisher's website.
Download or read book Common Cyclicites in Seismicity and Water Level Fluctuations at the Charlevoix Seismic Zone of the St Lawrence River written by Georgios Padelis Tsoflias and published by . This book was released on 1991 with total page 152 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Seismicity Processes in the Charlevoix Seismic Zone Eastern Canada written by Azadeh Fereidoni and published by . This book was released on 2014 with total page 202 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Charlevoix Seismic Zone (CSZ) is the most seismically active region in eastern Canada, based on the historical and current rate of activity. Several papers contend that the current seismicity in the CSZ represents long-lived aftershock sequences of the 1663 M~7 earthquake, in which the aftershock activity has persisted for hundreds of years. The aim of this thesis is to explore the influence of the 1663 earthquake on the current seismicity in the CSZ. The first part of the thesis has focused on developing a comprehensive earthquake database required for analysis of seismicity. The second part of the thesis has been devoted to characterization of seismicity in the CSZ in both time and space, with the goal of developing greater insight into the nature of intraplate seismicity in this region. The evidence from statistical analysis suggests that the current seismicity in the CSZ is not predominantly composed of the aftershock activity of past large earthquakes; the ongoing seismicity is therefore expected to continue in the region, and the zone should be considered an ongoing source of seismic hazard. However, I emphasize that this does not eliminate the possibility that earthquake activity in Charlevoix is still influenced by the stress changes imparted by the 1663 earthquake in the surrounding crust. The Coulomb stress analysis used in the present thesis shows that the stress triggers and shadow cast by the 1663 earthquake still exert influence on earthquake occurrence in Charlevoix after centuries.
Download or read book New and Revised Earthquake Focal Mechanisms of the Charlevoix Seismic Zone Canada written by M. de La Montagne and published by . This book was released on 1998 with total page 302 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Numerical Modeling of Seismic Wave Propagation written by K. R. Kelly and published by SEG Books. This book was released on 1990 with total page 540 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Waveform Inversion and Modeling of Seismic Data from Earthquake Sources Hydraulic Fracturing and Reflection Surveys written by Yafei Wu and published by . This book was released on 1996 with total page 202 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Geological Abstracts written by and published by . This book was released on 1988 with total page 524 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Seismological Research Letters written by and published by . This book was released on 2003 with total page 574 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Stress in the Lithosphere written by American Geophysical Union and published by . This book was released on 1992 with total page 330 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Physics Briefs written by and published by . This book was released on 1990 with total page 942 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Spring Meeting written by American Geophysical Union. Meeting and published by . This book was released on 1991 with total page 752 pages. Available in PDF, EPUB and Kindle. Book excerpt:
