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Since 1966, China has been using apparent resistivity observation to forecast strong aftershocks of the Xingtai earthquake. Retrospective studies of subsequent strong earthquakes have shown that anomalies in apparent resistivity observation before earthquakes usually exhibit anisotropic characteristics. In addition to the anisotropic changes in apparent resistivity before earthquakes, factors such as subway operation near the observation area, metal pipeline networks, and changes in water levels have also been found to cause anisotropic changes. These factors are called environmental interference factors. Therefore, distinguishing between anisotropic changes before earthquakes and anisotropic changes caused by interference and eliminating the effects of interference is crucial for using apparent resistivity observations for forecasting. Taking the observation of Hefei seismic station in Anhui Province as an example, a model is constructed using the finite element method to try to establish a method for analyzing anisotropy in apparent resistivity before earthquakes, and the data from other provincial stations are used for verification. In the modeling process, the influence coefficient is a measure of the relationship between the variation in apparent resistivity and the changes in the medium of the measurement area. The following results are obtained by calculating the influence coefficient using the finite element method: the influence coefficient between the power supply electrode and the measuring electrode of the apparent resistivity observation is negative, and the rest are positive, and the distribution of the influence coefficient shows obvious symmetry, with the axis of symmetry being the line connecting the electrodes and its midline, and the absolute value of the influence coefficient is inversely proportional to the distance from the electrodes. In addition, according to the constructed finite element model, the amplitude of anisotropic changes caused by interference can be quantitatively calculated. Given that interference is ubiquitous in various regions of the world, this study can provide a reference for international earthquake forecasters to quantitatively remove environmental interference in anisotropy. Moreover, when building apparent resistivity stations in seismic areas for earthquake prediction, it is best to avoid areas with larger local influence coefficients to ensure that the anomalous data before the earthquake is true and reliable. [ABSTRACT FROM AUTHOR]

The Load/Unload Response Ratio (LURR) is a seismic prediction method based on the dynamic evolution of the stress-strain relationship of rocks. By adopting Benioff strain as the response indicator, an in-depth analysis was conducted on the LURR anomalies within 400 km of the epicenter and its surrounding areas before the Ms7.4 earthquake in Madoi, Qinghai Province, on 22 May 2021. The analysis revealed that the LURR value peaked 1 month before the earthquake and then declined within half a month, indicating that the rock medium in the seismic gestation area was approaching the end of its yielding phase. Further investigation using the Outgoing Longwave Radiation (OLR) data from the National Oceanic and Atmospheric Administration (NOAA) satellite was conducted to study the short-term and imminent anomalous evolution of ground longwave radiation values after the high values declined (from May 14 to 25). The results showed that, spatially, significant and continuous OLR anomalies were observed only in the northern area of the epicenter before the earthquake, and these anomalies exhibited a trend of expanding towards the epicenter. Temporally, the entire anomalous evolution process can be divided into six phases: initial warming, anomaly expansion, peak intensity, anomaly weakening, earthquake occurrence, and anomaly disappearance. To validate this finding, the spatiotemporal evolution characteristics of LURR and OLR within 300 km of the epicenter and its surrounding areas before the Ms6.4 earthquake in Yangbi, Yunnan Province, on 21 May 2021, were analyzed, and similar patterns were found. These results suggest that the high LURR value before its decline may mark the end of the rock medium's yielding phase, and OLR data can reflect, to some extent, the state of tectonic stress accumulation along active faults in a critical condition. A comprehensive study of the anomalous evolution characteristics of these two physical parameters before the earthquake is not only conducive to the continuity from long-term to short-term forecasts but also of great significance for more accurately assessing the trend of seismic activity. [ABSTRACT FROM AUTHOR]

This paper reports the results of a geoelectrical survey carried out to investigate the Montaguto earth-flow, located in the southern Apennines (Campania Region, southern Italy). The aim of the survey was to reconstruct the geometry of the landslide body, to improve the knowledge on the geological setting and to indirectly test the effectiveness of a drainage system. Although electrical resistivity contrasts in the electrical images were not very pronounced, due to the lithological characteristic of the outcropping lithotypes, it was possible to observe the presence of both lateral and vertical discontinuities that were associated with lithological boundaries, physical variation of the same material and sliding surfaces. The geoelectrical information obtained was provided to the Italian National Civil Protection Department technicians and was considered for the planning of more appropriate actions for the stabilization and safety of the slide. [ABSTRACT FROM AUTHOR]

Since 2007, a permanent magnetotelluric (MT) monitoring station has been working in the seismic area of the Agri Valley (Basilicata region, southern Italy) in order to investigate the stability of the MT transfer function. The station was installed in a rural area near the supposed seismogenic fault of the strong earthquake (Mw = 6.9) that struck the Agri Valley in 1857. Analysing about 4 yr of MT data characterized by a low seismic activity, the long-term systematic variations of robust single station MT transfer function estimates were observed in two different sounding period ranges. First, a significant seasonal component of variability for short periods was noted; these short periods were up to 16 s and were linked to variations in wetting/drying of soil moisture in the shallower layers. Second, a connection between the monitored estimates and global geomagnetic activity, Ap index, was found, particularly in the [20–100 s] period range. Analysing remote reference results and tipper estimates in shorter monitoring window, it was shown that such effect cannot be explained by a local or incoherent noise, and a large-scale coherent source should be claimed. We show that this effect is subtle because it produces smooth estimates, satisfying the dispersion relationship between apparent resistivity and phase, with small error bars. As the global geomagnetic activity level increases, robust estimators, like the median value, can be considered as a representative of the estimates due to the natural source, and they tend to stabilize when the Ap index approaches 10. It is also worth noting that our monitored time window includes the recent global minimum of solar activity which occurred in 2009, thus enhancing the estimate dependence on the Ap index. [ABSTRACT FROM PUBLISHER]

The Italian Association of the GPR (Associazione Italiana del Georadar) is a no-profit Association devoted to the diffusion at national level of good practices in GPR prospecting. The association offers formation and free consultancy to its members, and organizes events open for the large community of GPR users and more in general for users of instruments for non-invasive or minimally invasive diagnostics (including near surface geophysical instruments, TDR probes, infrared cameras and so on). The Association, moreover, has the mission to favour (as far it can) the adoption of fair regulations at national level and awareness about safety issues and regulations. The Association was born in 2016 with only three members, but currently it involves more than 30 members from all Italy plus a member from Malta and includes also some important companies. The Association has held five schools: four of them have been national and have guaranteed formation credits for geologists and one of them has been international, organized together with the Sapienza University, the University College of London and the TU1208 GPR Association. All the schools have included practical session, showing, depending on the case, traditional systems, high frequency systems for prospecting on walls and masonries, systems equipped with arrays of antennas, stepped frequency systems and TDR probes. Videos have been recorded too and have been put on line on a reserved part of the web site of the association (www.gpritalia.it), so that now the members of the association have at disposal more than 30 hours of lessons on GPR and more in general on geophysical and electromagnetic issues. The Association has been slowly but constantly increasing in the last three years, and we are trustful that it will still grow up, because its mission answers to a niche but real demand existing in the country. In particular, there is a demand of quality in GPR and non-invasive prospecting, that is becoming and still more will become an important aspect for the planning and the management of the towns, the cultural heritage and more in general the territories. [ABSTRACT FROM AUTHOR]