On Operational Earthquake Forecast and Prediction Problems.

In his SSA presidential address (Jordan, 2014), and later in a more extended publication with coauthors (Jordan et al., 2014), Jordan presents a vision of forecast and prediction problems of earthquake system science. As experienced practitioners and in full appreciation of scientific studies on earthquake forecasting, we find it necessary to share a complementary viewpoint

On self-similarity of premonitory patterns in the regions of natural and induced seismicity

Anticipating the scale invariance of rock fracturing processes, we applied Keilis-Borok's algorithm M8, originally designed for identifying times of increased probability (TIPS) of occurrence of strong earthquakes (M < 8.0), retrospectively to Koyna earthquakes which occurred in the region after the impoundment of the Shivaji Sagar reservoir in 1962. The algorithm which enables diagnosis of TIPS from the 7th year onwards after the commencement of the earliest available data set showed that the 5.3 magnitude earthquake of 20 September 1980 indeed occurred within a time of increased probability. This result, apart from its potential application to recognizing future TIPS in the region, points to selfsimilarity between the premonitory patterns of natural and induced earthquakes and to scale-invariant nature of their processes. Further, a typical precursory rise in seismicity followed by a relative quiescence was also found to precede all the three larger earthquakes of the sequence

Распознавание образов в задачах оценки сейсмической опасности

The paper is devoted to some aspects of application of pattern recognition algorithms in solving problems of strong earthquake-prone area determination that can be used for seismic hazard assessment. The main principles of the having a long-term history approach to recognition of strong earthquake-prone areas (EPA) in a region under consideration on the basis of its morphostructural zoning scheme applying the algorithms “CORA-3” and “HAMMING” are described. A review of the results obtained in this direction and work on the development of new algorithms based, in particular, on discrete mathematical analysis is given. The use of pattern recognition approaches to develop algorithms for medium-term earthquake prediction that can help to obtain an operative seismic hazard assessment is shown. The application of the Unified Scaling Law for Earthquakes for the earthquake hazard and risk assessment taking into account the EPA results is considered. A review of the EPA and earthquake hazard and risk assessment results for the Caucasus region is presented.Статья посвящена некоторым аспектам применения алгоритмов распознавания образов при решении задач определения мест возможного возникновения сильных землетрясений, что может быть использовано для оценки сейсмической опасности. Приведены основные принципы имеющего многолетнюю историю подхода к распознаванию мест сильных землетрясений (РМСЗ) рассматриваемого региона на базе схемы его морфоструктурного районирования с применением алгоритмов «Кора-3» и «Хемминг». Дан обзор полученных в этом направлении результатов и работ по разработке новых алгоритмов, основанных, в частности, на дискретном математическом анализе. Отмечено использование подходов распознавания образов для создания алгоритмов среднесрочного прогноза землетрясений, с помощью которых может быть получена оперативная оценка сейсмической опасности. Рассмотрено применение Общего закона подобия для землетрясений для оценки сейсмической опасности и рисков с учетом результатов РМСЗ. Приведен обзор результатов РМСЗ и оценки сейсмической опасности и рисков для региона Кавказа

On the external forcing of global eruptive activity in the past 300 years

The decryption of the temporal sequence of volcanic eruptions is a key step in better anticipating future events. Volcanic activity is the result of a complex interaction between internal and external processes, with time scales spanning multiple orders of magnitude. We review periodicities that have been detected or correlated with volcanic eruptions/phenomena and interpreted as resulting from external forces. Taking a global perspective and longer time scales than a few years, we approach this interaction by analyzing three time series using singular spectral analysis: the global number of volcanic eruptions (NVE) between 1700 and 2022, the number of sunspots (ISSN), a proxy for solar activity, the polar motion (PM) and length of day (lod), two proxies for gravitational force. Several pseudo-periodicities are common to NVE and ISSN, in addition to the 11-year Schwabe cycle that has been reported in previous work, but NVE shares even more periodicities with PM. These quasi-periodic components range from ~5 to ~130 years. We interpret our analytical results in light of the Laplace's paradigm and propose that, similarly to the movement of Earth's rotation axis, global eruptive activity is modulated by commensurable orbital moments of the Jovian planets, whose influence is also detected in solar activity

Earthquake prediction: basics, achievements, perspectives

The recent scientific advances in understanding the hierarchical nature of the lithosphere and its dynamics based on systematic monitoring and evidence of its space-energy similarity at global, regional, and local scales did result the design of reproducible intermediate-term middle-range earthquake prediction technique. The real-time experimental testing aimed at prediction of the largest earthquakes world-wide from 1992 to the present proved statistically a possibility of practical earthquake forecasting although of limited precision. In the first approximation, an accuracy of 1-5 years and 5-10 times the  anticipated source dimension is achieved. Further analysis of seismic dynamics allows reducing the spatial uncertainty down to 1-3 source dimensions, although at the cost of additional failures-to-predict. Despite of limited accuracy a considerable damage could be prevented by timely knowledgeable use of the existing predictions and earthquake prediction strategies. The link of theoretical research in modeling earthquake sequences in frames of statistical physics on the one hand and instrumental and algorithm developments on the other hand help developing a new generation of earthquake prediction technique of higher accuracy

Predictability of geomagnetic series

The aim of this paper is to lead a practical, rational and rigorous approach concerning what can be done, based on the knowledge of magnetic series, in the field of prediction of the extreme geomagnetic events. We compare the magnetic vector differential at different locations computed with different resolutions, from an entire day to minutes. We study the classical correlations and the simplest possible prediction scheme to conclude a high level of predictability of the magnetic vector variation. The results obtained are far from a random guessing: the error diagrams are either comparable with earthquake prediction studies or out-perform them when the minute sampling is used in accounting for hourly magnetic vector variation. We demonstrate how the magnetic extreme events can be predicted from the hourly value of the magnetic variation with a lead time of several hours. We compute the 2-D empirical distribution of consecutive values of the magnetic vector variation for the estimation of conditional probabilities of different types. The achieved results encourage further development of the approach to prediction of the extreme geomagnetic events.Key words. Ionosphere (modeling and forecasting) – Magnetospheric physics (storms and substorms