How to Predict Earthquakes with Microsequences and Reversed Phase Repetitive Patterns

A strong earthquake is always preceded by groupings of shocks whose identification and understanding constitute a sound method for improving short-term earthquake forecasts. Thanks to a graphical method, we have identified and classified some microsequences and reversed phase repetitive patterns that precede the hazardous events. The seismic microsequences include a series of information useful to know in advance the beginning of energy release and accumulation phases that usually precede and follow a moderate-to-high magnitude earthquake. Their identification and correct interpretation allow us to determine various warning signals. In particular, through the analysis of their shape and position in the seismic sequence we can claim that the strongest earthquakes occur shortly after the formation of some peculiar micro-sequences. The checks carried out on large data sets related to earthquakes occurred in the past have shown that the analysis procedures developed do not depend on the size of the area analyzed while predicting a high percentage of moderate-to-high magnitude earthquakes.

Correlation of Upper Devonian and Lower Carboniferous Depositional Sequences in Different Facies Belts on Southern Margin of Upper Yangtze Platform

A fundamental problem in sequence stratigraphy is whether the sequences are global in extent and whether the sea level changes are eustatic in nature. Study on the Upper Devonian and Lower Carboniferous depositional sequences in different facies belts on the southern margin of the Upper Yangtze platform shows that different orders of sequences possess distinctive distribution and correlation in space, although the sea level changes in various orders of sequences may be primarily global in nature. The present paper regards the distribution in space, especially in different facies belts, as a criterion for defining and recognizing the various orders of sequences. The orthosequence (third order sequence) is probably global in nature, which may be discerned in various depositional facies belts on the continental margin and can be correlated over long distances, sometimes maybe worldwide. Commonly, correlation of the subsequences (fourth order sequences with time interval of 0.5 Ma to 1.5 Ma) is difficult in different facies belts, although some of them are probably also worldwide in distribution. A subsequence should be distinguishable and correlatable within at least one facies belt. The higher order sequences, including parasequences (fifth order sequences) and microsequences (sixth order sequences), are regional or local in distribution. They may have reflected the longer and shorter Milankovitch cycles respectively. Orthosequences and subsequences are usually recognizable in different facies belts, while parasequences and microsequences may be distinguished only in shallow marine deposits, but not in slope and basin facies deposits.

Double Earthquakes Classification and Seismic Precursors

In this paper, we examine both the sequence and organisation of major shallow earthquakes occurred in various areas of the world from 1904 to 2017. We aim to describe their major features and how they are connected with foreshocks and aftershocks immediately close in time and space. Examining magnitude value’s fluctuations over time, we see that they form a basic pattern, consisting of three maxima, one of which is central, and two or more events preceding and following it, whose magnitude, in some cases, may be comparable. The retrospective analysis of earthquakes’ patterns of high comparable magnitude has allowed their classification along with the development of some statistically significant relationships between epicentral distance and magnitude difference and between time interval and delay among maxima as well as the identification of activation signals predicting their occurrence. The pattern we identified in seismic sequences analysis, in relation to minor shocks-generated activation signals’ positions may be used to obtain useful information for the evolutionary study of seismic sequences and for predicting double and multiple earthquakes. The graphic analysis procedure applied to the pattern enables us to know the period of seismic sequence’s greatest hazard after a strong earthquake.

Short-Term Earthquake Forecast with the Seismic Sequence Hierarchization Method

All strong earthquakes are preceded by branching structures having different durations whose development scheme is partly largely predictable because it follows a well organized and recognizable pattern. By using a seismic sequence hierarchization method, this study graphically explains the preparation process of an earthquake, called “branching structure”. In addition, criteria apt to distinguish the structures that will produce shocks of average magnitude from strong earthquakes’ will be defined. Based on the temporal oscillations of the magnitude values, we explain the procedure for identifying the developmental stages that characterize the energy accumulation stage of the branching structure, in order to early detect the energy release stage’s trigger point and obtain information on how it will develop over time. The study identifies also some pre-signals (trigger points) of various magnitudes in the energy release stage, which allows us to early predict the foreshocks and mainshock time position. The method we developed constitutes a truly innovative approach for the earthquake forecasting analysis, which dramatically differs from those developed so far, as it considers the structure of the seismic sequence not only as a magnitude values’ oscillation, but also as a sequence of developmental stages that may begin much earlier.

How to Identify Foreshocks in Seismic Sequences to Predict Strong Earthquakes

The time analysis of seismic events preceding several strong earthquakes occurred in recent decades throughout the world, has highlighted some foreshocks’ characteristics, which are helpful for their discrimination compared to other types of events. These features can be identified within the seismic sequence and used as strong events’ precursors. Through the energy release pattern analysis, which precedes any strong earthquakes, in this study we describe some graphical procedures suitable for distinguishing a foreshock from any other type of earthquake. We have broadly divided foreshocks into two classes, depending on their position within the energy release pattern, by describing some relationships between the foreshock’s magnitude and the following earthquake’s. The results obtained show how the energy release pattern of some major earthquakes has distinctive features and repeatability which it is possible to obtain information from in order to perform sufficiently reliable short-term forecasts.

Seismic Sequences’ Branching Structures: Long-Range Interactions and Hazard Levels

Branching structures can provide early information on earthquakes’ preparation process, trigger stage, different breaking patterns that can occur before strong earthquakes and hazard levels reached in the area to be analyzed. In this study, we aim to understand the earthquakes long-range interactions which constitute the nodes of higher order seismic rods in the upper branching structure, and the hazard level reached in each developmental stage as well as to provide a warning time frame for the most energetic seismic events and a sound method to obtain information on the epicentral area. To this end, we have analyzed several branching structures by using both local and global seismicity. The analysis of different branching structures both on global and local scale highlights long-range interactions between the most energetic earthquakes and their triggering by smaller shocks, thus suggesting that the triggering can occur few minutes to decades before the earthquake, depending on a seismic sequence’s development speed and its structure.

Criteria for defining and recognizing the various orders of sequences in outcrop sequence stratigraphy

The regional distribution in different depositional facies belts is here regarded as an important criterion for defining and recognizing the various orders of sequences. The third-order sequence is possibly global in nature, which may be discerned in different depositional facies belts in one continental margin and can be correlated over long distances, sometimes even worldwide. Commonly, correlation of subsequence (fourth-order sequence with time interval of 0.51.5 Ma) is difficult in different facies belts, although some of them may also be worldwide in distribution. A subsequence should be able to discern and correlate within at least one facies belt. The higher-order sequences, including microsequence (fifth-order sequence) and minisequence (sixth-order sequence), are regional or local in distribution. They may reflect the longer and shorter Milankovitch cycles respectively. Sequence and subsequence are usually recognizable in different facies belts, while microsequence and minisequence may be distinguished only in shallow marine deposits, but not in slope and basin facies deposits. A brief discussion is made on the essential conditions for correct identification of sequences, useful methods of study, and problems meriting special attention in outcrop sequence stratigraphy.