Estimating the Epicenter of a Future Strong Earthquake in Southern California, Mexico, and Central America by Means of Natural Time Analysis and Earthquake Nowcasting

Earthquake Nowcasting: Retrospective Testing in Greece

Earthquake nowcasting (EN) is a modern method of estimating seismic risk by evaluating the progress of the earthquake (EQ) cycle in fault systems. EN evaluation is based on a new concept of time, termed 'natural time'. EN employs natural time, and uniquely estimates seismic risk by means of the earthquake potential score (EPS), which has been found to have useful applications both regionally and globally. Amongst these applications, here we focused on Greece since 2019, for the estimation of the EPS for the largest-magnitude events, MW(USGS) ≥ 6, that occurred during our study period: for example, the MW= 6.0 WNW-of-Kissamos EQ on 27 November 2019, the MW= 6.5 off-shore Southern Crete EQ on 2 May 2020, the MW= 7.0 Samos EQ on 30 October 2020, the MW= 6.3 Tyrnavos EQ on 3 March 2021, the MW= 6.0 Arkalohorion Crete EQ on 27 September 2021, and the MW= 6.4 Sitia Crete EQ on 12 October 2021. The results are promising, and reveal that the EPS provides useful information on impending seismicity.

Natural Time Analysis of Global Seismicity

Natural time analysis enables the introduction of an order parameter for seismicity, which is just the variance of natural time χ, κ1=⟨χ2⟩−⟨χ⟩2. During the last years, there has been significant progress in the natural time analysis of seismicity. Milestones in this progress are the identification of clearly distiguishable minima of the fluctuations of the order parameter κ1 of seismicity both in the regional and global scale, the emergence of an interrelation between the time correlations of the earthquake (EQ) magnitude time series and these minima, and the introduction by Turcotte, Rundle and coworkers of EQ nowcasting. Here, we apply all these recent advances in the global seismicity by employing the Global Centroid Moment Tensor (GCMT) catalog. We show that the combination of the above three milestones may provide useful precursory information for the time of occurrence and epicenter location of strong EQs with M≥8.5 in GCMT. This can be achieved with high statistical significance (p-values of the order of 10−5), while the epicentral areas lie within a region covering only 4% of that investigated.

Insurance as an Alternative for Sustainable Economic Recovery after Natural Disasters: A Systematic Literature Review

The risk of natural disasters has increased over the last few decades, leading to significant economic losses across the globe. In response, research related to the risk of economic loss due to natural disasters has continued to develop. At present, insurance remains the best solution for funding such losses. The purpose of this study is to analyse the development of insurance as an alternative for sustainable economic recovery after natural disasters. The data used are articles obtained from several sources indexed by Scopus and Google Scholar. The search resulted in a final database of 266 articles, culled from a total of 813 articles before the final selection was made. The articles used are publications from 2000–2021 (including 21 database periods), to which we applied a systematic literature review method. Identification and evaluation of the articles was carried out through visualization of their content, development of disaster risk insurance, and availability of disaster risk insurance by country and type. The identification results show that the relationship between the word “insurance”, according to visualization using the VOSviewer software, has a relationship with other clusters including the words “disaster”, “disaster insurance”, “risk”, “natural disaster”, “study”, “recovery”, and “disaster risk financing”. The 266 articles studied show that there was an annual increase in the number of published scientific papers over the period 2000–2021. The types of disaster risk insurance, based on a review of the articles, include agricultural insurance, flood insurance, property insurance, earthquake insurance, crop insurance, and natural disaster insurance. In addition, of the six types of disaster risk insurance, three have been discussed the most in the last five years, namely, agricultural, flood, and property insurance. The increase in the number of scientific publications discussing these three types of disaster risk insurance has been influenced by climate change. Climate change causes a significant increase in the potential for disasters and is accompanied by an increased risk of loss. This review is expected to provide information and motivation for researchers related to the development and importance of disaster risk insurance research. Research in the risk sector for disaster losses due to climate change should be continued in the future in order to help fund economic recovery, especially throughout the insurance sector. With continuous research on disaster risk insurance, it is hoped that the resulting information can be more effective in determining insurance risk and in helping local economies and communities recover after the advent of a disaster. With the availability of funds for post-disaster recovery, the regional economy affected by the disaster can be immediately restored and recovered from adversity.

Nonlinear Statistical Features of the Seismicity in the Subduction Zone of Tehuantepec Isthmus, Southern México

After the M8.2 main-shock occurred on 7 September 2017 at the Isthmus of Tehuantepec, Mexico, the spatial distribution of seismicity has showed a clear clusterization of earthquakes along the collision region of the Tehuantepec Transform/Ridge with the Middle America Trench off Chiapas. Furthermore, nowadays, the temporal rate of occurrence in the number of earthquakes has also showed a pronounced increase. On the basis of this behavior, we studied the sequence of magnitudes of the earthquakes which occurred within the Isthmus of Tehuantepec in southern Mexico from 2010 to 2020. Since big earthquakes are considered as a phase transition, after the M8.2 main-shock, one must expect changes in the Tehuantepec ridge dynamics, which can be observed considering that the b-value in the Gutenberg–Richter law, has also showed changes in time. The goal of this paper is to characterize the behavior of the seismic activity by using the Gutenberg–Richter law, multifractal detrended fluctuation analysis, visibility graph and nowcasting method. Those methods have showed important parameters in order to assess risk, the multifractality and connectivity. Our findings indicate, first that b-value shows a dependency on time, which is clearly described by our analyses based on nowcasting method, multifractality and visibility graph.