Geo-Chemical Techniques for Earthquake Forecasting in Nigeria

Regardless of the doubt caused by some rounds on the impossibility of earthquake forecast, more and more countries, even at the highest governmental levels, realize that doing nothing is the ostrich position of dread before the real difficulties associated with the creation of a real forecasting system. Nigeria in times past was believed to be aseismic. However, the seismic record of Nigeria from 1933-2021 have demonstrated in contrast to the idea, numerous quakes have been recorded in Nigeria throughout the years. With the development of observation techniques and theoretical knowledge of geochemistry, geochemical observation of faults gas has become a hotspot once more in recent years. Rn, Hg, H2, etc., are used for geochemical observations. 222Rn has a half-life of 3.825 days, a magnitude 5.0 earthquake will be detected through precursory phenomena at a distance not greater than 142 km. Mercury and other elements are used as important detectors for earthquake prediction and they play an important role in revealing the relationship between fluid in the fault zone and the occurrence of earthquakes, the range for a magnitude 5.0 earthquake is limited to 200 km. Hydrogen concentrations have been monitored for precursory variations in many fault systems, using either discrete sampling and laboratory analysis or continuous monitoring of ground gas, using hydrogen-sensitive fuel cells. Precursory changes in groundwater chemistry are often attributed to the mixing of fluids from two or more chemically distinct aquifers, the physical mechanism responsible for the mixing of fluids is, however, not well established.

Tukey Control Chart for Radon Monitoring in Relation to the Seismic Activity

Radon is one of the precursory phenomena that exist in connection to the occurrence of earthquakes and may have potential in forecasting these hazards. The data set in this study contains the observations of radon from August 01, 2014, to January 31, 2015, collected in Sobra city, northern Pakistan. Weibull, gamma, log-normal, log-logistic, and Pareto probability distribution were fitted over the radon on its original scale and a log scale. Log-logistic best fits the radon on both scales. The Tukey control charts reveal several anomalies that were compared with earthquake occurrence. There are five earthquakes that occurred during the same period as the radon monitoring program, having magnitude ranges between 4.9 and 5.5, with the ratio between strain radius and distance to the epicenter greater than or equal to 1. The results of this study demonstrate that, for earthquakes, seismic events show a correlation with increasing concentrations of radon gas before their occurrence.

From Hector Mine M7.1 to Ridgecrest M7.1 Earthquake. A Look from a 20-Year Perspective

The paper provides a comparative analysis of precursory phenomena in the ionosphere and atmosphere for two strong earthquakes of the same magnitude M7.1 that happened in the same region (North-East from Los Angeles) within a time span of 20 years, the Hector Mine and Ridgecrest earthquakes. Regardless of the similarity of their location (South-Eastern California, near 160 km one from another), there was one essential difference: the Hector Mine earthquake happened during geomagnetically disturbed conditions (essential in the sense of ionospheric precursors identification). In contrast, the quiet geomagnetic conditions characterized the period around the time of the Ridgecrest earthquake. The Hector mine earthquake happened in the middle of the rising phase of the 23-rd solar cycle characterized by high solar activity, while the Ridgecrest earthquake happened by the very end of the 24th cycle under very low solar activity conditions. We provide a comprehensive multi-factor analysis, determine the precursory period for both earthquakes and demonstrate the close similarity of ionospheric precursors. Unlike the majority of papers dealing with earthquake precursor identification based on the “abnormality” of observed time-series mainly determined by amplitude difference between “normal” (usually climatic) behavior and “abnormal” behavior with amplitudes exceeding some pre-established threshold, we used the technique of cognitive recognition of the precursors based on the physical mechanisms of their generation and the morphology of their behavior during the precursory period. These permits to uniquely identify precursors even in conditions of disturbed environment as it was around the time of the Hector Mine earthquake. We demonstrate the close similarity of precursors’ development for both events. The leading time of precursor appearance for the same region and similar magnitude was identical. For the Hector Mine it was 11 October 1999—5 days in advance—and for 2019 Ridgecrest it was 28 June—7 days before the mainshock and five days before the strongest foreshock.

Tukey Control Chart for Radon Monitoring in Relation to the Seismic Activity

Earthquakes are among the most destructive natural disasters, which cause damage on a huge scale not only to life but to property also. Radon is one of the precursory phenomena that exist in connection to the occurrence of earthquakes and may have potential in forecasting these hazards. The data set in this study contains the observations of radon from August 01, 2014, to January 31, 2015 collected in Sobra city, northern Pakistan. Weibull, Gamma, Log-Normal, Log-Logistic, and Pareto probability distribution were fitted over the radon on its original scale and a log scale. Log-logistic best fits the radon on both scales. Log-logistic based Tukey control charts suggest a central limit of 2465.459 Bq/m3 and upper control limit of 12704.080 Bq/m3 on the original radon data, while they suggest a central limit of 7.759, upper control limit of 11.080 and lower control limit of 4.524 on the log scale. The Tukey control charts reveal several anomalies that were compared with earthquake occurrence. There are five earthquakes that occurred during the same period as the radon monitoring program, having magnitude ranges between 4.9 5.5, with the ratio between strain radius and distance to the epicenter greater than or equal to 1. Among several radon anomalies exceeding the upper control limit, the five are identified as earthquake precursors. The results of this study demonstrate that for earthquakes, seismic events show a correlation with increasing concentrations of radon gas before their occurrence.

Geological and Geophysical Factors Constraining the Occurrence of Earthquake Precursors in Geofluids: A Review and Reinterpretation

In this paper, we update the previous compilations of observed earthquake precursors from the published scientific literature of the last decade. We collected the epicentral coordinates, magnitude, hypocentral depth of each earthquake and the distance from the observed precursor and its time lag. The locations are reported and compared with data concerning geological and geophysical parameters like global seismicity, volcanic locations, heat flow and tectonic regimes. Possible relations between geological and geophysical parameters and the occurrence of fluid-related earthquake precursors are considered and discussed. Some geological and geophysical conditions can be deemed responsible for the occurrence of fluid-related earthquake precursory phenomena. Geophysical models used to explain the occurrence of earthquake precursors are discussed with the purpose of contributing to engineering proper monitoring networks. Areas of the world potentially suitable for earthquake fluid-related precursor monitoring are suggested.

Strategies for Earthquake Disaster Reduction Using Soil Radon Monitoring in Taiwan

<p>Earthquakes constitute a severe source of human disasters all around the world. However, one has to note, following the reviews on earthquake prediction, that at the present day no detectable, systematic and reliable precursory phenomena precede large earthquakes. Indeed, even if some precursory phenomena have been identified subsequent to many earthquakes, there are no statistically based reliable data for the recognition of a method based on the search for precursors. So, it’s necessary to make different prevention strategies to reduce the impact of disaster due to impending earthquakes in the region. The island of Taiwan is a product of the collision between the Philippine Sea plate and Eurasian plate which makes it a region of high seismicity. Active subduction zones occur south and east of Taiwan. Geochemical anomalies in soil gas and groundwater are commonly observed prior to impending earthquake and volcanic eruptions, attracting considerable attention in studies on precursory geochemical signals. Geochemical variations of soil-gas composition in the vicinity of geologic fault zone of Northeastern and Southwestern parts of Taiwan have been studied in detail recently. To carry out the investigation, temporal soil-gases variations are measured at continuous earthquake monitoring stations established along different faults. In present study, we have correlated observed soil-gas anomalies with some earthquakes magnitude ≥ 5 occurred in the region during the observation. The data is processed using a different kind of filters to reduce the noise level. It helps us to filter out the high-frequency noise and daily variation caused by different parameters. However, radon anomalies in all cases are not only controlled by seismic activity but also by meteorological parameters which make isolation of earthquake precursory signals complicated. Characteristics of temporal variability of soil-gas radon concentrations have also been examined using Singular Spectrum Analysis. Digital filter has been applied in eliminating the long term trend in the data and retains variations of less than 30 days<strong>. </strong>The radon variations exhibit dominant daily variations, which are controlled by atmospheric temperature inducted evaporation in surface water saturated soil (Capping Effect). The causal relationship is marked by a clear phase lag of 2-3 hours in the sense that peak in daily variation of radon succeeds the peak in temperature. Aperiodic variations in soil radon intensity in the range of 2-10 days are negatively correlated with temperature whereas positively correlated with pressure. To integrate our data with our working procedure, we use the popular and famous open source web application solution, AMP (Apache, MySQL, and PHP), creating a website that could effectively show and help us manage the real-time database. Based on the anomalous signatures from particular monitoring stations we are in a state to identify the area for impending earthquakes for the proposed tectonic based model for earthquake forecasting in Taiwan.</p>

A Comparative Study of Geoelectric Signals Possibly Associated with the Occurrence of Two Ms > 7 EQs in the South Pacific Coast of Mexico

During past decades, several studies have suggested the existence of possible seismic electric precursors associated with earthquakes of magnitude M > 7 . However, additional analyses are needed to have more reliable evidence of pattern behavior prior to the occurrence of a big event. In this article we report analyses of self-potential Δ V records during approximately two years in three electro-seismic stations in Mexico located at Acapulco, Guerrero; Petatlán, Guerrero and Pinotepa Nacional, Oaxaca. On 18 April 2014 an M s 7.2 earthquake occurred near our Petatlán station. Our study shows two notable anomalies observed in the behavior of the Fourier power spectrum of Δ V for ultra low frequency ULF-range, and the transition of the α l -exponent of the detrended fluctuation analysis of the Δ V time series from uncorrelated to correlated signals. These anomalies lasted approximately three and a half months before the main shock. We compare this electric pattern with another electric signal we reported associated with an M s 7.4 that occurred on 14 September 1995 at Guerrero state, Mexico. Our characterization of the anomalies observed in both signals point out similar features that enrich our knowledge about precursory phenomena linked to the occurrence of earthquakes of magnitude M > 7 .

Statistical Significance of Earth’s Electric and Magnetic Field Variations Preceding Earthquakes in Greece and Japan Revisited

By analyzing the seismicity in a new time domain, termed natural time, we recently found that the change of the entropy under time reversal (Physica A2018, 506, 625–634) and the relevant complexity measures (Entropy2018, 20, 477) exhibit pronounced variations before the occurrence of the M8.2 earthquake in Mexico on 7 September 2017. Here, the statistical significance of precursory phenomena associated with other physical properties and in particular the anomalous variations observed in the Earth’s electric and magnetic fields before earthquakes in different regions of the world and in particular in Greece since 1980s and Japan during 2001–2010 are revisited (the latter, i.e., the magnetic field variations are alternatively termed ultra low frequency (ULF) seismo-magnetic phenomena). Along these lines we employ modern statistical tools like the event coincidence analysis and the receiver operating characteristics technique. We find that these precursory variations are far beyond chance and in addition their lead times fully agree with the experimental findings in Greece since the 1980s.