Periodic Reporting for period 2 - SMR (Seismic Moment and Recurrence (SMR) using Luminescence Dating Techniques)
Berichtszeitraum: 2019-06-01 bis 2020-05-31
The aim of the SMR project is to explore the use of the luminescence techniques to date fault rock related materials which are directly associated with past earthquake events and develop detailed methodologies on the use of the luminescence dating techniques for palaeoseismology and neotectonic studies.
To achieve this, SMR adopts a multi-analytical approach and investigates the zeroing potential of the luminescence signal of minerals, by employing experimental simulations of tectonic processes in the laboratory, combined with luminescence dating of samples collected from real fault zones (not subject to laboratory simulations). Having achieved this, it is necessary the development of detailed analytical procedures on the use of luminescence dating techniques, suitable specifically for fault rock related materials and the successful establishment of faults past rapture events.
The SMR project has established the potential of fault-rock material (fault slickensides and gouge) to be used for luminescence and ESR dating. Analyses have indicated that minerals in fault-rocks have experienced repeated cataclastic deformation and been subject to various physical and chemical processes as well as pressure and temperature conditions which probably allow for the resetting of their luminescence/ESR signal (a prerequisite for the use of the two dating methods). Our analysis suggests that the employment of the different luminescence dating techniques can produce reliable dating results and are potentially reliable methods for direct dating fault-rock material, with luminescence ages in a number of cases studies, producing a series of ages representing neotectonic activity of the selected faults.
The results of the project could ultimately affect the way earthquake prediction and risk assessment research is carried out in Europe and worldwide, creating bridges between different fields of knowledge for infrastructure planning and design but also for mitigation measures.
To achieve this, SMR adopts a multi-analytical approach and investigates the zeroing potential of the luminescence signal of minerals, by employing experimental simulations of tectonic processes in the laboratory, combined with luminescence dating of samples collected from real fault zones (not subject to laboratory simulations). Having achieved this, it is necessary the development of detailed analytical procedures on the use of luminescence dating techniques, suitable specifically for fault rock related materials and the successful establishment of faults past rapture events.
The SMR project has established the potential of fault-rock material (fault slickensides and gouge) to be used for luminescence and ESR dating. Analyses have indicated that minerals in fault-rocks have experienced repeated cataclastic deformation and been subject to various physical and chemical processes as well as pressure and temperature conditions which probably allow for the resetting of their luminescence/ESR signal (a prerequisite for the use of the two dating methods). Our analysis suggests that the employment of the different luminescence dating techniques can produce reliable dating results and are potentially reliable methods for direct dating fault-rock material, with luminescence ages in a number of cases studies, producing a series of ages representing neotectonic activity of the selected faults.
The results of the project could ultimately affect the way earthquake prediction and risk assessment research is carried out in Europe and worldwide, creating bridges between different fields of knowledge for infrastructure planning and design but also for mitigation measures.
Initially, a number of samples from five faults (Mattinata Fault-Italy, Rodopos fault in Crete-Greece, Arkitsa fault zone-Central Greece, Nojima Fault-Japan, Asano Fault-Japan and Arima Fault-Japan) were collected, as these faults represent different characteristics in relation to the material developed in their brittle zones which in turn affect the mechanical strength and stability of faults differently. Following this step, the collected fault zone materials were characterized, by perfoming microstructural, mineralogical and chemical analyses. Petrographic thin sections were prepared and the microstructural characteristics of the bulk brittle material samples were observed by Scanning Electron Microscope (SEM). Quantitative chemical analyses on polished thin sections were made using Energy-Dispersive Spectrometry (EDS). Mineralogical analyses by X-ray diffraction (XRD) were made to observe different mineral structures. This gave the opportunity to identify and characterize brittle fault zone materials that contain suitable minerals for luminescence dating (e.g. quartz and feldspar). This also gave the opportunity to examine the thermal history (as a result of faulting) of the samples as minerals illite and chlorite undergo changes on heating.
Assessment of the zeroing potential of the luminescence signal of minerals contained in materials found on faults zone was a crucial step towards achieving the aim of the project. To this end, stress-simulations in the laboratory were performed using a shear High-Velocity Rotary Friction (HVRF) machine, to investigate the frictional processes and the dynamic strength of the samples, and also the mechanical results and the developing microstructures, within the brittle material layer. Experiments were conducted at varying slip rates, displacements, normal stresses and ambient conditions, to test the dependence of the strain distribution. Mechanical data as well as the temperature close to the slip surface were recorded during the experiments. Following the stress-simulation experiments, samples were chemically treated to isolate the minerals suitable for luminescence measurements (quartz and feldspar) and their luminescence signals were measured using a number of different luminescence techniques (OSL, ITL, IRSL). Luminescence investigated “zeroing” of the luminescence signals, as a result of the different stress simulation conditions.
The next step of the project was the development of methodological procedures on the use of luminescence dating techniques, suitable specifically for deformed geological formations and the establishment of palaeoerthquake ages of selected faults. To achieve this, luminescence measurements were employed on samples of selected faults and experimental approaches were followed to establish the appropriate parameters for luminescence dating, suitable specifically for deformed geological formations.
A necessary step to validate the dating results of the project was to perform a number of cross-checks of the luminescence-dated samples. ESR dating was performed on a number of samples used in luminescence dating and results were compared with the luminescence ages obtained. Additionally, luminescence ages of selected faults were judged against the available historical information on previous activations.
The SMR project systematically disseminated the research results and methods to the scientific community and general public through different channels including notes, participation in various international conferences, talks and lectures in educational bodies, websites and publications in peer-reviewed international journals. The dissemination of the research results enabled their exploitation by the scientific/academic community, leading to new research possibilities and new collaborations between research centres.
Assessment of the zeroing potential of the luminescence signal of minerals contained in materials found on faults zone was a crucial step towards achieving the aim of the project. To this end, stress-simulations in the laboratory were performed using a shear High-Velocity Rotary Friction (HVRF) machine, to investigate the frictional processes and the dynamic strength of the samples, and also the mechanical results and the developing microstructures, within the brittle material layer. Experiments were conducted at varying slip rates, displacements, normal stresses and ambient conditions, to test the dependence of the strain distribution. Mechanical data as well as the temperature close to the slip surface were recorded during the experiments. Following the stress-simulation experiments, samples were chemically treated to isolate the minerals suitable for luminescence measurements (quartz and feldspar) and their luminescence signals were measured using a number of different luminescence techniques (OSL, ITL, IRSL). Luminescence investigated “zeroing” of the luminescence signals, as a result of the different stress simulation conditions.
The next step of the project was the development of methodological procedures on the use of luminescence dating techniques, suitable specifically for deformed geological formations and the establishment of palaeoerthquake ages of selected faults. To achieve this, luminescence measurements were employed on samples of selected faults and experimental approaches were followed to establish the appropriate parameters for luminescence dating, suitable specifically for deformed geological formations.
A necessary step to validate the dating results of the project was to perform a number of cross-checks of the luminescence-dated samples. ESR dating was performed on a number of samples used in luminescence dating and results were compared with the luminescence ages obtained. Additionally, luminescence ages of selected faults were judged against the available historical information on previous activations.
The SMR project systematically disseminated the research results and methods to the scientific community and general public through different channels including notes, participation in various international conferences, talks and lectures in educational bodies, websites and publications in peer-reviewed international journals. The dissemination of the research results enabled their exploitation by the scientific/academic community, leading to new research possibilities and new collaborations between research centres.
SMR has already progress beyond the state of the art. SMR approach included independent cross-checks (by ESR dating) to validate the ages obtained using luminescence dating techniques, something that has not been done before. An additional element that goes beyond the state of the art is the combination of: a) the examination of the luminescence characteristics of fault rock related materials which have been subject to experimental simulations of tectonic processes in the laboratory and b) luminescence measurements of the same materials which have not been used in the simulation experiments. Thus, allowing the investigation of the luminescence signal resetting effect. To this end, new luminescence dating analytical procedures were developed, providing clear guidance on directly dating fault rock related materials, thus facilitating the assessment of the seismic histories of seismically active areas and eventually earthquake forecasting. Further, the methodologies which were developed can become part for geo-hazards evaluations, adding to the efforts for effectively addressing societal safety, thus contributing to a reduction in the risk posed to European population, both in terms of human and financial losses. From the perspective of the HORIZON 2020, the objectives of the SMR project were fully contributed to the enhancement of European Union competitiveness and excellence in the thematic areas of “Secure societies”.