Variations revealed by INFREP Radio Network in correspondence of six earthquakes with MW greater than 5.0 occurred in the Balkan Peninsula and Adriatic Sea on 26 and 27 November, 2019

In this work we analyse variations in VLF/LF radio signal amplitudes recorded by the INFREP network in the period 16 November – 6 December, 2019 characterized by very intensive seismic activities in the Balkan peninsula, Crete, and Adriatic, Aegean and Black seas. Namely, 38 earthquakes with magnitude greater than 4.0 occurred in this area during the noticed period; the most intensive of them occurred on 26 and 27 November: three events in Albania (Mw= 6.4, 5.3, 5.1), one in Crete (Mw= 6), one in Bosnia and Herzegovina (Mw= 5.4) and two in Adriatic sea (Mw= 5.4, 5.3). We study both long- and short- term variations that are already recorded in earlier studies. The long-term variations relate to changes in the amplitude intensities in periods of several days and their existence is shown in many previous studies. The recent analyses also indicate short-term variations in signal amplitude noises started about several tents of minutes before the earthquake (Nina et al. 2020). In this work, we analyse different areas using INFREP network, which allow us to study local changes in the atmosphere. In order to examine possible precursors we considered longer time started and ended 10 days before and after the most intensive of the considered earthquakes, respectively

Sodium butyrate improves growth performance of weaned piglets during the first period after weaning

The purpose of the present work was to evaluate whether the addition of sodium butyrate to feed could facilitate wean- ing and growth response in piglets. For 56 days two groups of 20 piglets (9.2±1.4 kg LW) were fed an acidified basal diet (containing formic and lactic acid at 0.5 and 1.5 g/kg of feed, respectively) without (control group) or with sodium butyrate (SB) at 0.8 g/kg. Average daily gain (ADG), daily feed intake (DFI), feed efficiency (FE) and live weight (LW) were recorded. In the first two weeks, butyrate supplementation increased ADG (+20%; P<0.05) and DFI (+16%; P<0.05). During the subsequent period (15 to 35 days) animals fed SB had a higher DFI but lower feed efficiency (+10% and -14%, respectively; P<0.05) than animals fed the control diet. No other benefits were observed thereafter. The data presented showed that the use of sodium butyrate facilitated only the initial phase of adaptation to a solid diet in piglets

Wavelet analysis applied on temporal data sets in order to reveal possible pre-seismic radio anomalies and comparison with the trend of the raw data

Since 2009, several radio receivers have been installed throughout Europe in order to realize the INFREP European radio network for studying the VLF (10-50 kHz) and LF (150-300 kHz) radio precursors of earthquakes. Precursors can be related to “anomalies” in the night-time behavior of VLF signals. A suitable method of analysis is the use of the Wavelet spectra. Using the “Morlet function”, the Wavelet transform of a time signal is a complex series that can be usefully represented by its square amplitude, i.e. considering the so-called Wavelet power spectrum. The power spectrum is a 2D diagram that, once properly normalized with respect to the power of the white noise, gives information on the strength and precise time of occurrence of the various Fourier components, which are present in the original time series. The main difference between the Wavelet power spectra and the Fourier power spectra for the time series is that the former identifies the frequency content along the operational time, which cannot be done with the latter. Anomalies are identified as regions of the Wavelet spectrogram characterized by a sudden increase in the power strength. On January 30, 2020 an earthquake with Mw= 6.0 occurred in Dodecanese Islands. The results of the Wavelet analysis carried out on data collected some INFREP receivers is compared with the trends of the raw data. The time series from January 24, 2020 till January 31, 2000 was analyzed. The Wavelet spectrogram shows a peak corresponding to a period of 1 day on the days before January 30. This anomaly was found for signals transmitted at the frequencies 19,58 kHz, 20, 27 kHz, 23,40 kHz with an energy in the peak increasing from 19,58 kHz to 23,40 kHz. In particular, the signal at the frequency 19,58 kHz, shows a peak on January 29, while the frequencies 20,27 kHz and 23,40 kHz are characterized by a peak starting on January 28 and continuing to January 29. The results presented in this work shows the perspective use of the Wavelet spectrum analysis as an operational tool for the detection of anomalies in VLF and LF signal potentially related to EQ precursors

Study of VLF/LF wave propagations above seismic areas

Abstract: We report on radio transmitter signals recorded in Europe by INFREP network which is mainly devoted to search for earthquakes electromagnetic precursors (Biagi et al., 2011). We consider in this analysis the detection of transmitter signals recorded by INFREP receivers located in different regions of Europe, i.e. Romania, Italy, Greece and Austria. The aim is the investigation of the electromagnetic environment above earthquakes regions. We selected seismic events which occurred in the year 2016 and characterized by a moment magnitude (Mw) above 5.0 and a depth of less than 50 km. A common method is applied to all events and which involves the analysis of the VLF/LF signal detection taking into consideration the following parameters: (a) the distance transmitters-receivers, (b) the signal to noise ratio during the diurnal and night observations, (c) the daily and night averaged amplitude and (d) the sunset and sunrise termination times. This leads us to specify the key factors which can be considered as criteria to distinguish and to identify earthquakes precursors. We discuss in this contribution the radio wave propagation in the D- and E-layers and their impacts on the VLF/LF amplitude signal. We show that the 'seismic anomaly' requests a more precise analysis of the 'quiet' and 'disturbed' ionospheric conditions and their corresponding spectral traces on the VLF/LF transmitter signals

Earthquakes Precursors and Earthquake Prediction: Recent Advances

Seismic hazard assessment and medium/long-term earthquakes forecasting have long been key research topics for the national governments interested in giving scientific bases to their building codes in earthquakes prone areas. Methods like the PSHA (Probabilistic Seismic Hazard Assessment, e.g. Cornell, 1968) were used to extrapolate from the (often very small) frequencies of past earthquakes the annual probability of occurrence of (even very large) earthquakes in the future. Such methods were strongly criticized for “… the significant consequences of their failures in terms of human and economic losses…” ( Wyss et al., 2012). In Japan “…since 1979, earthquakes that caused 10 or more fatalities … actually occurred in places assigned a relatively low probability” ( Geller, 2011). In the same country the underestimation of the Tohoku earthquake (March 11th 2011, MW = 9.0) intensity by the Japanese National Seismic Hazard Maps and the intrinsic limits of PSHA were at last officially recognized (e.g., Kagan and Jackson, 2013 and Fujiwara et al., 2013). Together with the 2011 Tohoku event, Stein et al. (2012) report other highly destructive earthquakes (e.g. 2008 Wenchuan, 2010 Haiti, etc.) occurred in areas predicted by to be relatively safe. The ground accelerations of most strong earthquakes occurred in 2000–2010 were significantly underestimated (Kossobokov and Nekrasova, 2012) by the GSHAP (Global Seismic Hazard Project) maps (based on PSHA). Not rarely, and often after a major earthquake, the probabilistic maps of seismic hazard require a revision with a general increase of the seismic hazard in the affected area (e.g. Bommer and Abrahamson, 2006). Such hazard underestimations (dramatically recognized only after disastrous earthquakes) are particularly frequent in areas where neither historical or instrumental events are reported in seismic catalogues. Their possible consequences were properly described in Peresan et al., 2013 and Artioli et al., 2013. In this context the interest in alternative observational techniques and appropriate data analysis methods to improve the seismic hazard assessment in the short-medium term increases every day. Various independent observations have been reported for many decades to support models describing the earthquake generation process as a non-random phenomenon that involves wide spatial and temporal scales often (even if not always) culminating in a large event in correspondence to some critical point. Anomalous changes in the physical/chemical state of the Earth lithosphere, atmosphere and ionosphere, which could be timely identified provided that adequate measurement systems are deployed and appropriate data analysis methods are used, can be associated to those processes. Several geophysical parameters (see for instance Tronin, 2006 and Cicerone et al., 2009, and reference herein) have been proposed as possible earthquake precursors for decades. Among them ground deformations (uplift and tilt), abrupt changes in gas emission rates, underground water level, temperature and chemical composition, electrical properties of rocks, atmosphere and ionosphere, near surface air temperature and relative humidity, and the Earth’s thermal emission were observed. A large number of theoretical models and laboratory experiments, which could explain the occurrence of the observed anomalies in relation with the preparatory phase of an earthquake (e.g. Scholz et al., 1973, Tronin, 1996, Pulinets and Boyarchuk, 2004, Freund et al., 2006, Pulinets and Ouzounov, 2011 and Tramutoli et al., 2013, etc.), were proposed at the same time. This special issue of the “Physics and Chemistry of the Earth” journal contains twenty-four articles, most of them presented at 2014 EGU Assembly, offering an updated review of the recent advances in the study of earthquake precursors and related physical phenomena

Variation of Altitude Observed on the Occasion of the Tohoku Earthquake (M = 9.0) Occurred on March 11, 2011

Copyright © 2014 Pietro Milillo et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. In accor-dance of the Creative Commons Attribution License all Copyrights © 2014 are reserved for SCIRP and the owner of the intellectual property Pietro Milillo et al. All Copyright © 2014 are guarded by law and by SCIRP as a guardian. Since October 1, 2010, a GPS receiver is put into operation at Tokai (Japan) in an experiment on Neutrino Phys-ics (T2K). A significant variation of the altitude was detected from the beginning of March 2011, so that it has made worthwhile to investigate the possibility that such variations could be correlated to the Tohoku earthquake. In order to investigate in details this possibility, we analyzed the GPS data collected during 2011 by GEONet the GPS Earth Observation Network (GEONET). GEONET is the GPS network of Japan and consists of 1240 per-manent stations. Preliminary results of the analysis seemed to show ten days before the earthquake, some possi-ble anomalous behaviors of the stations. These anomalous behaviors were particularly relevant for stations of the network near the epicentral area. While co-seismic and post-seismic variations are widely expected, the anoma-lies recorded about ten days before the earthquake could be seriously considered among short-term precursors of the earthquake. In order to confirm this possibility, more detailed studies have been performed. In particular

Le variazioni di inclinazione dell'ala sinistra del delta del Tevere nel periodo Gennaio 1979 - Giugno 1980.

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