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.

Seismicity Patterns Prior to the Thessaly (Mw6.3) Strong Earthquake on 3 March 2021 in Terms of Multiresolution Wavelets and Natural Time Analysis

On 3 March 2021, a strong, shallow earthquake of moment magnitude, Mw6.3, occurred in northern Thessaly (Central Greece). To investigate possible complex correlations in the evolution of seismicity in the broader area of Central Greece before the Mw6.3 event, we apply the methods of multiresolution wavelet analysis (MRWA) and natural time (NT) analysis. The description of seismicity evolution by critical parameters defined by NT analysis, integrated with the results of MRWA as the initiation point for the NT analysis, forms a new framework that may possibly lead to new universal principles that describe the generation processes of strong earthquakes. In the present work, we investigate this new framework in the seismicity prior to the Mw6.3 Thessaly earthquake. Initially, we apply MRWA to the interevent time series of the successive regional earthquakes in order to investigate the approach of the regional seismicity at critical stages and to define the starting point of the natural time domain. Then, we apply the NT analysis, showing that the regional seismicity approached criticality a few days before the occurrence of the Mw6.3 earthquake, when the κ1 natural time parameter reached the critical value of κ1 = 0.070.

Feasibility and Interest of Continuous Diaphragmatic Fatigue Monitoring Using Wavelet Denoising in ICU and Anesthesia

Measures of diaphragmatic electromyography (Edi), and respiratory mechanics, have demonstrated early changes before clinical complications. However, automatic Edi data collection is not adequate today due mainly to severe artefacts as well as to loss of signal. We thus intended to develop a new device with embedded artificial intelligence to optimize automatic Edi recordings independantly of artefacts and of probe displacement. We first chose the best mathematical tool to denoise Edi, using an established database, giving multiresolution wavelets as the best, resulting in the permanent availability of the H/L spectral index, a recognized representative of diaphragmatic fatigue. Fatigue was simultaneously measured using the classical mechanical f/Vt index (Rapid Shallow Breathing Index, RSBI), as well as the transdiaphragmatic pressure. We then performed a comparison of real-time H/L and RSBI in a group of seven healthy volunteers, before and during midazolam sedation infusion 0.1 mg.kg-1, with a parallel CPAP administration (2.5, 5.0, and 10 cm H2O) intended to compensate for airways resistance due to midazolam. Procedure was ended by delivering the antagonistic flumazenil 0.2 to 0.5 mg.kg-1. Progressive fatigue due to midazolam, the relief due to CPAP, as well as the answer to the anatgonist flumazenil, were shown earlier by the H/L index than by the RSBI change. Our new H/L monitoring device may greatly improve clinical follow-up of anesthetized patients as well as help to determine the optimal period for ventilatory weaning in ICU (Clinical Trials NCT00133939).