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Title: Geodynamic and seismological investigation of the South Hellenic Arc structure
Author: Chatzopoulos, Georgios
ISNI:       0000 0004 7961 7598
Awarding Body: Brunel University London
Current Institution: Brunel University
Date of Award: 2018
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This thesis examines foreshock and aftershock seismicity patterns with the accelerated seismic release model and the non-extensive statistical physics approach in the South Aegean. The convergence and subduction of the African lithosphere under the Aegean Sea plate creates the seismically active Hellenic Arc. Strong earthquakes occur frequently, with evidence of a great magnitude earthquake in the past. To evaluate and understand the large earthquake likelihood, the accelerated seismic release model (ASR) has been used as hazard estimation technique. This method uses a power law equation to quantify the cumulative energy release (or Benioff strain, or number events) from the earthquakes that occur before the large event. The mainshocks are considered as critical points while the foreshocks are evolution pattern of the critical phenomena. A theoretical model to explain the earthquake preparation process has been proposed. This is based on the energy conservation laws and non-extensive statistical physics. The analytic expressions of the proposed model indicate the existence of a common critical exponent in the ASR power law equation. In addition, the critical exponent is independent from the measured quantity and reflects the physical parameters of the critical area, such as the Euclidian dimension, the Guttenberg-Richer b-value and the extensivity of the system during the large earthquake preparation period. The evaluation of the proposed model has been carried out with the identification of the critical areas for three strong events in South Aegean with retrospective analysis. The two strong event aftershocks of 2013 and a swarm sequence occurred in 2016 have been located and relocated in order to evaluate the spatiotemporal attributes of these sequences. Cross sections and fault plane solution provided in the examination of the spatial distribution of the events. By combining the detailed aftershock and foreshock catalogues, it is possible to better understand the activation mechanisms. Also, the time differences between two continuous earthquakes (interevent time) has been examined with the ideas of non-extensive statistical physical. The results suggest that a distribution of the entropic index q could explain the extensivity of the system as the q value varies with time. The use of the non-extensive statistical physics has clearly helped to better understand the behaviour of the seismicity patterns.
Supervisor: Collins, P. ; Valianatos, F. Sponsor: European Social Fund
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Accelerated semitics patterns ; Aftershock sequences location-relocation ; Non-extensive statistial physics ; Intervent times ; foreshock-aftershock sequence pattern correlation