Monitoring temporal variations in the geothermal activity of Miocene Lesvos volcanic field using remote sensing techniques and MODIS - LST imagery

Abstract Many islands of the Aegean Sea show strong geothermal activity due to volcanism in the area. In this paper, Robust Satellite Techniques (RST) are used to isolate, from other known possible sources, those thermal anomalies possibly related to geothermal activity in the Miocene volcanic field of Lesvos Island (Northern Aegean). For this purpose, 12 years (2003–2014) of daily Night-time Land Surface Temperature (LST) products, from Moderate Resolution Imaging Spectroradiometer (MODIS) acquisitions were analyzed. The final dataset contained 770 thermal anomalies whose spatial correlation with geological and structural data of Lesvos - such as caldera rims, ring faults, major tectonic lineaments and hydrothermal alterations mapped by processing SENTINEL-2 MSI satellite images – has been particularly investigated. In the approximately 20 ma geothermal field of Lesvos, geothermal activity seems to be also associated with the extensional regime of the broader area that leads to lithosphere thinning and consequent heat transfer in the multi-fractured terrain of Lesvos through volcanic and tectonic faults. Achieved results seem to confirm the possibility to use RST-based thermal anomalies to identify temporal variations in the geothermal activity probably due to the uplifting and circulation of the hydrothermal waters

The use of acoustic emissions technique in the monitoring of fracturing in concrete using soundless chemical demolition agent

Soundless chemical demolition agents (SCDAs) have been used during the last decades in the demolition of boulders and concrete structures as well as in open-surface and sub-surface rock excavation, as an alternative to the use of explosives posing safety risks. However, the knowledge of the governing fracture mechanisms in brittle materials is rather limited. In the present work, we thoroughly investigate the use of the acoustic emission technique to study the SCDA-induced fracture process in concrete blocks. Energy-related features and waveform parameters of the recorded AE activity are correlated to the fracture mode of the concrete where a quasi-static behavior is observed. Monitoring of the progressive fracture is also achieved by the 3D localization of the AE sources. The distribution of the inter-event times of the recorded hits is further analyzed in the context of non-extensive statistical physics

A Non-Extensive Statistical Mechanics View on Easter Island Seamounts Volume Distribution

In the volcanic complex processes, inherent long-range interactions exist suggesting that Non-Extensive Statistical mechanics could be used to describe fundamental properties of the system. Based on the non-extensive Tsallis entropy a frequency-volume distribution function is suggested for the Easter Island-Salas y Gomez seamounts chain. Our results demonstrate the applicability of fundamental principles of Tsallis entropy to derive the cumulative distribution of seamounts volumes. The work suggests that the processes responsible for hotspot seamount formation are complex and the cumulative frequency-volume distribution of seamounts in the Easter Island/Salas y Gomez Chain (ESC) are well-described by a q-exponential function. The analysis leads to a non-extensive index q = 1.54 in agreement with that presented in other geodynamic or laboratory scale effects

A Non-Extensive Statistical Mechanics View on Easter Island Seamounts Volume Distribution

In the volcanic complex processes, inherent long-range interactions exist suggesting that Non-Extensive Statistical mechanics could be used to describe fundamental properties of the system. Based on the non-extensive Tsallis entropy a frequency-volume distribution function is suggested for the Easter Island-Salas y Gomez seamounts chain. Our results demonstrate the applicability of fundamental principles of Tsallis entropy to derive the cumulative distribution of seamounts volumes. The work suggests that the processes responsible for hotspot seamount formation are complex and the cumulative frequency-volume distribution of seamounts in the Easter Island/Salas y Gomez Chain (ESC) are well-described by a q-exponential function. The analysis leads to a non-extensive index q = 1.54 in agreement with that presented in other geodynamic or laboratory scale effects

The Evolution of Preseismic Patterns Related to the Central Crete (Mw6.0) Strong Earthquake on 27 September 2021 Revealed by Multiresolution Wavelets and Natural Time Analysis

On 27 September 2021, a shallow earthquake with focal depth of 10 km and moment magnitude Mw6.0 occurred onshore in central Crete (Greece). The evolution of possible preseismic patterns in the area of central Crete before the Mw6.0 event was investigated by applying the method of multiresolution wavelet analysis (MRWA), along with that of natural time (NT). The monitoring of preseismic patterns by critical parameters defined by NT analysis, integrated with the results of MRWA as the initiation point for the NT analysis, forms a promising framework that may lead to new universal principles that describe the evolution patterns before strong earthquakes. Initially, we apply MRWA to the interevent time series of the successive regional earthquakes in order to investigate the approach of the regional seismicity towards critical stages and to define the starting point of the natural time domain. Then, using the results of MRWA, we apply the NT analysis, showing that the regional seismicity approached criticality for a prolonged period of ~40 days before the occurrence of the Mw6.0 earthquake, when the κ1 natural time parameter reached the critical value of κ1 = 0.070, as suggested by the NT method

On the statistical physics of rockfalls: A non-extensive view

Based on the non-extensive Tsallis entropy, a distribution function of rockfall sizes is suggested. Our result demonstrates the applicability of fundamental principles of non-extensivity of fragmentation into the cumulative distribution of rockfall volumes. Historical data discussed along with an analysis of recent rockfalls data where the observed volumes estimated using the high-accuracy and precision technique of terrestial laser scanner (TLS). The analysis leads to the non-extensive index q = 1.4 in agreement with that presented in other fracture effects in geodynamic or laboratory scale. The work suggests that the non-extensive physics approach can lead to a groundbreaking statistical physics of rockfalls, one of the worldwide natural hazard

On the non-extensivity in Mars geological faults

A non-extensive statistical physics approach is tested for the first time in a planetary scale, for the fault length distribution in Mars estimated a non-extensive q-parameter equal to 1.277 for normal faults and 1.114 for thrust ones. The latter support the conclusion that the fault systems in Mars are subadditive ones in agreement with recent observations for faults in Earth and Valles Marineris extensional province, Mars. In addition, an analysis of the global Mars fault system as a mixed one, consisted of the normal and thrust subsystems with different q-parameters is presented, leading to q = 1.22

Modelling earthquake diffusion as a Continuous-Time Random Walk with Fractional Kinetics: The case of the 2001 Agios Ioannis earthquake swarm (Corinth Rift)

International audienc

3D Body-Wave Velocity Structure of the Southern Aegean, Greece

This study delves into the southern Aegean regionwhere the subduction of the oceanic Mediterranean lithosphere under the Aegean continental one takes place. This region is considered one of the most active ones in the eastern Mediterranean Sea due to intense tectonic movements in the Late Quaternary. More than 1200 manually revised events from 2018 to 2023 have been used in order to obtain the 3D structure of body-wave velocity and VP/VS ratioto 80 km depth through earthquaketomography. A series of resolution tests have been performed and demonstrated fair resolution of the derived velocity structures in the area of interest. The derived anomalies of body-waves (dVP, dVS) and VP/VS ratio provided important information about the southern Aegean regional tectonics and secondarily active faults of smaller scale (>20 km). The region is marked by significant low-velocity anomalies in the crust and uppermost mantle, beneath the active arc volcanoes. The seismicity related to the Hellenic Subduction Zone (HSZ) is connected to a low-angle positive anomaly of VP and VS, correlated withthe observed intermediate-depth seismicity (H ≥ 40 km) in this part of the study area. This result could be related to the diving HSZ slab

Is pressure stimulated current relaxation in amphibolite a case of non-extensivity?

The application of uniaxial stress on rocks is accompanied by the production of an electric signal which is described by the term pressure stimulated current (PSC). In this work the high rate step stress (HRSS) technique is applied, and the PSC relaxation in amphibolite samples from KTB drilling, is studied in the frame of non-extensive statistical mechanics. After the application of an abrupt stress step, a PSC spike is recorded up to its maximum value PSCmax, decreasing gradually, right after the stress stabilization in a value σH. In the present work we study PSCs relaxation in uniaxial compressed rocks using a generalized exponential function called q-exponential, which explicitly introduces hierarchically constrained dynamics and interactions. The interactions are associated with the non-extensive entropy parameter q which exhibits a behavior indicating a dependence with the applied uniaxial stress as we approach fracture. The stress-dependent q-estimation leads to the conclusion that fracturing is a subextensive process with hierarchically constrained dynamics. Furthermore, assuming an assembly of relaxed subdomains created due to microfracture, a non-extensive behavior of the observed macroscopically PSC relaxation is discussed in the frame of a superstatistical approach