Littérature scientifique sur le sujet « Macroseismicity »

Abstract In recent years, the French seismological, geodetic, and gravimetric community has been structured within Réseau Sismologique et géodésique Français (RESIF) (French seismological and geodetic network). In addition to instrumental developments, RESIF has structured the work on French seismicity (metropolitan and overseas) within the RESIF transverse seismicity action (ATS). The purpose of this article is to present the ATS and the way it is structured to propose to the community different products: seismicity bulletin and catalog, historical and instrumental macroseismicity data, and ShakeMaps. The places where these products can be found are indicated, as well as the way they are realized and the improvements in progress for a better realization and availability. The link with European plate observing system is also underlined.

The Wenchuan earthquake of the 12th of May 2008, in Sichuan county of China can be classified as a large scale event based on the tectonic structures that triggered the earthquake and the effects caused on the human, structural and natural environment. The aim of this paper is to present the geotectonic and seismotectonic regime of the earthquake affected region based on field data along the seismic fault zone and an attempt is made towards the: (i) estimation of the intensity values according to EMS1998 (European Microseismic Scale, 1998) and ESI2007 (Environmental Seismic Intensity Scale, 2007) and the determination of their geographical distribution in a macroscale, (ii) interpretation of the intensity values data and their distribution according to the seismotectonic, geodynamic and geotechnical regime, and (iii) conduction of a comparative evaluation review on the application of both EMS1998 and ESI2007. The application of both EMS1998 and ESI2007 and the comparative evaluation of the results indicate that the estimated values of EMS1998 and ESI2007 were almost in agreement, despite the fact that the geographical locations of assessment data were different suggesting that the application and use of both scales appears to represent a useful and reliable tool for seismic hazard estimation.

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences, 2016.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 173-181).
This thesis focuses on the source mechanisms of Earthquakes of different scales, from the micro-seismicity in oil/gas fields in Oman, to moderate earthquakes in Kuwait, and finally to pico-seismicity, i.e. acoustic emission, in the laboratory. To investigate the source mechanisms as well as their uncertainties, a waveform-based Bayesian moment tensor inversion approach was developed and validated by synthetic tests. The Bayesian approach estimates the source parameters and the uncertainties by generating a posterior probability density function of the source parameters. The effects of location, velocity model, and error model of the data on the posterior prediction of the source parameters are discussed. This Bayesian moment tensor inversion method was first applied to the well-documented induced seismicity data in an oil/gas field in Oman. On Chapter 3, we move on to another mideast country - Kuwait. We conducted ground motion calculations in Kuwait due to regional large earthquakes and to local seismicity. We found that the regional earthquakes with low-frequency and long-duration surface waves were most likely to affect tall buildings, while the local smaller earthquakes are most likely to affect small and old structures constructed before the adoption of building codes. Using the Bayesian moment tensor inversion method, we studied the source mechanisms of local earthquakes in Kuwait. Historically, Kuwait has low local seismicity; however, in recent years the KNSN has monitored more and more local earthquakes. In 2015, two local earthquakes - Mw4.5 on 03/21/2015 and Mw4.1 on 08/18/2015 - have been recorded by both the Incorporated Research Institutions for Seismology (IRIS) and KNSN, and were widely felt by people in Kuwait. Most earthquakes in Kuwait occurred close to oil/gas fields. The earthquakes are generally small (Mw < 5) and are shallow with focal depths of about 2 to 8 km. We determined the location and source mechanism of these local earthquakes, with the uncertainties, using a Bayesian inversion method. Our results show that most likely these local earthquakes occurred on pre-existing faults and may have been triggered by oil field activities. In Kuwait, where oil fields are close to populated areas, these induced earthquakes could produce ground accelerations high enough to cause damage to local structures. Chapter 4 is devoted to the study of acoustic emissions during the rock fracturing experiments in the laboratory. The laboratory fracturing can produce pico-seismicity with magnitude as small as -7. Three event-detection and three location algorithms have been implemented to the acoustic emission (AE) data from the fracturing experiment of a cylindrical Berea sandstone sample (Diameter: 36.43 mm; Height: 76.7 mm). The first P-amplitude and waveform-based Bayesian moment tensor inversion algorithms have been applied to the AE data to study the source mechanisms of this fracturing related pico-seismicity. The location, and sensor calibration are discussed in the thesis. The main contribution from this thesis are: 1) Developing a waveform-based Bayesian moment tensor approach; 2) Understanding the source mechanisms of local earthquakes in Kuwait, and simulating the ground motion due to regional and local earthquakes in Kuwait; 3) Characterizing the laboratory-scale fractures using the fracturing related acoustic emission data.
by Chen Gu.
Ph. D.