Prediction Of Large Earthquakes Research Articles

New paleoseismic events reveal decamillenial recurrence time for large earthquakes (M ≥ 7) along the Yuguang Graben Fault in North China

Paleoseismic studies are critical for the assessment and prediction of large earthquakes (M ≥ 7). These studies involve excavating and analyzing evidence from surface–rupturing earthquakes. However, they often face limitations in spatiotemporal resolution. The Yuguang Graben, located in the northern Shanxi Grabens of North China, contains an abundance of Quaternary loess that can be utilized for extending paleoseismic records. Fine-grained deposits of loess contrast sharply with gravel deposits of the colluvial wedge, making the wedge shape apparent. To enhance our understanding of earthquake behavior in the Yuguang Graben, we excavated a trench on terrace T2 of the Songzhikou segment of the Yuguang Graben Fault (YGF). We used LiDAR to obtain a high–resolution orthophoto of the trench wall. Through OSL dating of colluvial wedges and loess, we identified at least four large paleoseismic events with a magnitude of M ≥ 7 that occurred along the YGF. These events took place at >77.6 ± 5.1, 63.9 ± 5.1, 51.0 ± 4.3, and 37.3 ± 0.3 kyr, respectively. Combined with previous paleoseismic studies, we identified seven paleoseismic events since the late Pleistocene. These findings reveal that earthquakes occurring on YGF follow a quasiperiodic pattern with an average recurrence interval of about 12 ± 3 kyr. The elapsed time of the most recent earthquake near the recurrence interval suggests an increased risk of a large earthquake along the YGF. We also analyzed earthquake clusters generated by neighboring faults in the active northeastern boundary of the Ordos block. Our analysis indicated that fault interactions can affect the recurrence interval of earthquakes along single faults, while regional seismic activity tends to concentrate in time during a seismically active period. These observations underscore the importance of expanding paleoseismic records and exploring regional seismic hazards to gain a more comprehensive understanding of earthquakes.

Preface to the Global Earthquake Forecasting System (GEFS) special issue: Towards using non-seismic precursors for the prediction of large earthquakes

Preface to the Global Earthquake Forecasting System (GEFS) special issue: Towards using non-seismic precursors for the prediction of large earthquakes

A combined estimator using TEC and b-value for large earthquake prediction

Ionospheric anomalies have been shown to occur a few days before several large earthquakes. The published works normally address examples limited in time (a single event or few of them) or space (a particular geographic area), so that a clear method based on these anomalies which consistently yields the place and magnitude of the forthcoming earthquake, anytime and anywhere on earth, has not been presented so far. The current research is aimed at prediction of large earthquakes, that is with magnitude Mw 7 or higher. It uses as data bank all significant earthquakes occurred worldwide in the period from January 1, 2011 to December 31, 2018. The first purpose of the research is to improve the use of ionospheric anomalies in the form of TEC grids for earthquake prediction. A space–time TEC variation estimator especially designed for earthquake prediction will show the advantages with respect to the use of simple TEC values. Further, taking advantage of the well-known predictive abilities of the Gutenberg–Richter law’s b-value, a combined estimator based on both TEC anomalies and b-values will be designed and shown to improve prediction performance even more.

Predictability of the Seismic Energy Flux: Southern Europe and the Mediterranean

The paper assessed the predictability of the seismic energy rate and large earthquakes in southern Europe and the Mediterranean according to the data from the United States Geological Survey catalog for 1900–2016. A nonlinear second-order differential equation is used as a mathematical model, and optimization and predictability estimation algorithms are this author’s. The estimates show a high predictability of energy rate trends. For 84 out of 217 large earthquakes in the region, we have found foreshock predictability, and aftershock predictability for 200 earthquakes. The predictability of large earthquakes begins to be seen at small (1.5–7.5 km) radii of hypocenter samples, increases rapidly at medium (15 and 30 km) radii, then more smoothly increases at a radius of 60 km and decreases slightly at a radius of 150 km. The predicted distance in time averages tens of days for foreshock predictability and thousands of days for aftershocks. The results demonstrate good prospects for the approximation–extrapolation approach to the prediction of both earthquakes themselves and the subsequent aftershock decay of seismic activity.

Anomalies in continuous GPS data as precursors of 15 large earthquakes in Western North America during 2007-2016

The preparation processes of large earthquake may start several or dozens of days before its actual occurrence. As scholars have observed the links between stationary GPS measurements of ground deformation and the occurrence of large earthquake, the continuous GPS data can be used as tools to identify such preparation processes. A method based on Martingale theory is proposed to extract the anomalies in continuous GPS data prior to 15 large earthquakes in western North America during 2007–2016. The precursory information of the anomalies for the corresponding earthquake is evaluated by using Molchan,s error diagram. The results validate that the extracted anomalies have a strong correlation with the short-impending large earthquakes. This demonstrates that changes of ground deformation recorded by GPS contain useful information for earthquake forecasting and the proposed method therefore can be used to improve the prediction of large earthquakes.

The predictability of seismicity and large earthquakes: Kamchatka 1962 to 2014

This paper reports the estimation of the predictability of seismicity and large earthquakes in Kamchatka as inferred from data in the Kamchatka regional catalog for 1962–2014. The mathematical model uses a second-order nonlinear differential equation, while the optimization algorithm and the estimates of predictability are the author’s own. The estimates show a high predictability of seismicity; the extrema of prediction nonlinearity typical of large earthquakes usually occur simultaneously with similar extrema of seismicity as a whole. Overall, 220 large (K ≥ 13.3) Kamchatka earthquakes were analyzed to find that foreshock predictability was available for 200 earthquakes (~30000 determinations) and aftershock predictability for 215 earthquakes (~300000 determinations). The predictability related to large earthquakes began to be seen and was rapidly increasing at intermediate (7.5–30 km) radii of hypocenter samples. The prediction distances over time were some tens and hundreds of days for foreshock predictability and some hundreds and thousands of days for aftershock predictability. These results demonstrate very good promise for the approximation extrapolation approach to the prediction of both large earthquakes themselves and of subsequent aftershock decay of seismic activity.

The predictability of seismicity and large earthquakes: Kamchatka 1962 to 2014

This paper reports the estimation of the predictability of seismicity and large earthquakes in Kamchatka as inferred from data in the Kamchatka regional catalog for 1962–2014. The mathematical model uses a second-order nonlinear differential equation, while the optimization algorithm and the estimates of predictability are the author’s own. The estimates show a high predictability of seismicity; the extrema of prediction nonlinearity typical of large earthquakes usually occur simultaneously with similar extrema of seismicity as a whole. Overall, 220 large (K ≥ 13.3) Kamchatka earthquakes were analyzed to find that foreshock predictability was available for 200 earthquakes (~30000 determinations) and aftershock predictability for 215 earthquakes (~300000 determinations). The predictability related to large earthquakes began to be seen and was rapidly increasing at intermediate (7.5–30 km) radii of hypocenter samples. The prediction distances over time were some tens and hundreds of days for foreshock predictability and some hundreds and thousands of days for aftershock predictability. These results demonstrate very good promise for the approximation extrapolation approach to the prediction of both large earthquakes themselves and of subsequent aftershock decay of seismic activity.

The Predictability of Seismicity and Large Earthquakes: Kamchatka 1962 to 2014

This paper reports the estimation of the predictability of seismicity and large earthquakes in Kamchatka as inferred from data in the Kamchatka regional catalog for 1962–2014. The mathematical model uses a second-order nonlinear differential equation, while the optimization algorithm and the estimates of predictability are the author’s own. The estimates show a high predictability of seismicity; the extrema of prediction nonlinearity typical of large earthquakes usually occur simultaneously with similar extrema of seismicity as a whole. Overall, 220 large (K ≥ 13.3) Kamchatka earthquakes were analyzed to find that foreshock predictability was available for 200 earthquakes (~30 000 determinations) and aftershock predictability for 215 earthquakes (~300 000 determinations). The predictability related to large earthquakes began to be seen and was rapidly increasing at intermediate (7.5–30 km) radii of hypocenter samples. The prediction distances over time were some tens and hundreds of days for foreshock predictability and some hundreds and thousands of days for aftershock predictability. These results demonstrate very good promise for the approximation extrapolation approach to the prediction of both large earthquakes themselves and of subsequent aftershock decay of seismic activity.

A long-term slow slip event from 1996 to 1997 in the Kii Channel, Japan

We present a long-term slow slip event from 1996 to 1997 in the Kii Channel along the Nankai Trough in southwestern Japan that has not been reported previously. The long-term slow slip event had a moment magnitude Mw 6.7 and a duration of 1 to 1.5 years. The magnitude of the event was smaller than those of the Tokai (Mw 7.1) and the Bungo Channel (Mw 7.0 to 7.1) events along the Nankai Trough. The slip was located slightly shallower than the depth of the low-frequency earthquakes around the Kii Channel. Long-term slow slips have been identified in various regions along the Nankai Trough, except in the Kii Peninsula. Unveiling the history of long-term slow slips is expected to contribute to an understanding of plate boundary characteristics as well as to the prediction of large earthquakes along the Nankai Trough.

Forecasting Ability of a Multi-Renewal Seismicity Model

The inter-event time, IET, is sometimes used as a basis for prediction of large earthquakes. It is the case when theoretical analysis of prediction is possible. Quite recently a specific IET- model was suggested for dynamic probabilistic prediction of M > 5.5 events in Italy . In this study we analyze both some aspects of the statistical estimation of the model and its predictive ability. We find that more or less effective prediction is possible within 4 out of 34 seismotectonic zones where seismicity rate or clustering of events is relatively high. We show that, in the framework of the model, one can suggest a simple zone independent strategy, which practically optimizes the relative number of nonaccidental successes, or the Hanssen-Kuiper, HK, skill score. This quasi-optimal strategy declares alarm in a zone for the first 2.67 years just after the occurrence of each large event in the zone. The optimal HK skill score values are: 26% for the 3 most active zones and 2-10% for the 26 least active zones. However, the number of false alarm time intervals per one event in each of the zones is unusually high: 0.7 and 0.8-0.95 respectively. Both these theoretical estimations are important because any prospective testing of the model is unrealistic in most of the zones during a reasonable time. This particular analysis requires a discussion of the following issues of general interest: a specific approach to the analysis of predictions vs. the standard CSEP testing approach; prediction vs. forecasting; HK skill score vs. probability gain; the total forecast error diagram and connected false alarms.

Comment on the report "Operational Earthquake Forecasting" by the International Commission on Earthquake Forecasting for Civil Protection

<p>The recently published report Operational Earthquake Forecasting: State of Knowledge and Guidelines for Utilization by the International Commission on Earthquake Forecasting for Civil Protection (ICEF) presupposes that there is no method for the short-term prediction of large earthquakes that has been demonstrated to be both reliable and skillful. This is no longer correct. Earthquakes can be deterministically stress-forecast by using shear-wave splitting to monitor stress-accumulation in the rock mass surrounding the earthquake source. This new understanding of fluid-rock deformation means that the recommendations of the ICEF Report are no longer appropriate. This comment reviews this new understanding and suggests that the way forward for operational earthquake forecasting in Italy is to install one or more controlled-source three-borehole Stress-Monitoring Sites and use shear-wave splitting to monitor stress-accumulation and stress-forecast all damaging (M ≥ 5) earthquakes in Italy.</p>

Principal component analysis method in the detection of total electron content anomalies in the 24 hrs prior to large earthquakes

The goal of this research is to examine one-dimensional total electron content (TEC) data using principal component analysis (PCA) to search for total electron content (TEC) anomalies associated with large earthquakes in 24 h prior to nucleation. The characteristics of principal eigenvalues generated for TEC prior to 24 earthquakes of magnitude scale M ≥ 5.0 and 6 lesser earthquakes of magnitude scale M < 5 that occurred in Taiwan from 01 January 2000 to 31 December 2001 are examined. In an earlier paper, I was able to confirm the statistical findings of Liu et al. (J Geophys Res 111, 2006) that sparse earthquake-associated TEC anomalies existed in 5 days prior to the 12 large earthquakes they examined (Lin, Terr Atm Ocean Sci, 2010). In this paper, I wish to examine the subtlety of principal component analysis in detecting earthquake-associated TEC anomalies by examining if such precursors can be detected in 24 h prior to large earthquakes. Of the earthquakes examined, TEC anomalies given by clear extreme principal eigenvalues were evident within 24 h of nucleation for 21 of the 24 earthquakes of M ≥ 5.0. After making allowance for the general status of background TEC, it is clear that these extreme principal eigenvalues are representative of earthquake-associated anomalies. For the smaller earthquakes (M < 5), it was not possible to differentiate earthquake-associated anomalies from background effects on TEC status. These new findings confirm the validity of PCA in searching for earthquake-associated TEC anomalies and show that it is subtle enough to detect TEC anomalies within 24 h leading to a large earthquake. If this approach continues to prove successful, it could theoretically be used in real-time prediction of large earthquakes through early detection of earthquake-associated TEC anomalies.

Interplate seismogenic zones along the Kuril–Japan trench inferred from GPS data inversion

Stress accumulation between earthquakes results from slip that is insufficient to fully accommodate plate movement. An inverse analysis of GPS data from the Kuril–Japan trench reveals a trench-parallel belt of stress accumulation with six peaks in the depth range of 10–40 km, suggesting potential source regions for future earthquakes. In the subduction zones around Japan, where four plates interact with one another, large earthquakes have occurred repeatedly1. These interplate earthquakes are part of the process of tectonic stress accumulation and release that is driven by relative plate motion2,3,4. Stress accumulation between earthquakes results from slip deficit (slip that is insufficient to fully accommodate plate movement). For the prediction of large earthquakes, it is therefore important to monitor the distribution of slip deficit on plate interfaces. Here we apply an inversion method based on Bayesian modelling (using direct and indirect prior information on the magnitude and distribution of fault slip5) to horizontal and vertical velocities from global positioning system data. For the seismically calm period between 1996 and 2000, we obtain a precise distribution of slip-deficit rates on the interface between the North American and Pacific plates around Japan, which reveals a trench-parallel belt of slip deficit with six peaks in the depth range of 10–40 km. These peaks agree with the source regions of past large interplate earthquakes along the Kuril–Japan trench. We conclude that the slip-deficit zones identified with our method are potential source regions of large earthquakes.

Three-Dimensional Finite-Difference Waveform Modeling of Strong Motions Observed in the Sendai Basin, Japan

We perform three-dimensional (3D) finite-difference (FD) waveform modeling of strong motions in the frequency range 0.2 to 1.67 Hz observed in the Sendai basin, Japan, during the Japan Meteorological Agency magnitude ( M J) 5.0 1998 Miyagiken-Nanbu earthquake. In a previous, we estimated S -wave velocity structures above the pre-Tertiary bedrock at six sites in the Sendai basin based on array records of microtremors. To interpolate these velocity structures in space we conduct single-station microtremor measurements at a total of 61 locations and estimate the S -wave velocity structure at each site by modeling the horizontal-to-vertical spectral ratio of fundamental mode Rayleigh waves. An initial 3D model of the basin is constructed using the velocity structures estimated from both array and single-station microtremor measurements, along with other information such as surface geology. This model encompasses a region 33 km long, 30 km wide, and 19 km deep. The final model is obtained through a trial-and-error process by fitting 3D FD synthetic waveforms to the bandpass-filtered (0.2 Hz to 1.67 Hz) displacement records 12 stations for the 1998 Miyagiken-Nanbu earthquake. We compute the synthetics using a fourth-order staggered-grid 3D FD method with variable grid spacing. As the 3D model is modified, the source parameters (strike, dip, rake, and seismic moment) are estimated by a grid search method using 1D site-specific models derived from the modified 3D model. The observed waveforms are reproduced well at most stations by the final 3D basin model. This agreement suggests the validity of the final 3D basin model for theoretical strong-motion prediction of large earthquakes in the frequency range from 0.2 to 1.67 Hz. Manuscript received 7 June 2000.

The Predictability of Large Earthquakes: Evidence from an Analogue Model of Earthquake Rupture

—The recurrence behaviour of large earthquakes, in several tectonic settings, has been explained by simple models of stress accumulation and release which assume that the fault stress state is solely a function of the far-field tectonic strain rate. However, the limited dataset of large event recurrence intervals has been a major obstacle to the verification of these and other models. We present the results from a simple analogue model of earthquake rupture and stick-slip which displays power-law frequency-size statistics and involves many cycles of large events. We show that, despite the macroscopic homogeneity of the model, large events do not conform to simple deterministic time- or slip-predictable patterns. However, when the recurrence intervals for large events are divided by the median recurrence interval, the normalized data are composed of two distinct lognormally distributed populations. One population is characterized by events which are strongly clustered in time with relatively short recurrence intervals and low moment release, the other by events which are weakly clustered in time with median-sized recurrence intervals. It is suggested that the long-term recurrence behaviour of large earthquakes, whilst being non-deterministic, may be modelled by a well-defined statistical distribution of recurrence intervals.

プレート境界における応力の蓄積過程と大地震の繰り返しに伴う地殻変動サイクルのモデル化について

For long-term prediction of large earthquakes at plate boundaries, it is important to develop an earthquake cycle model which can numerically simulate the processes of crustal deformation and stress accumulation at and around plate boundaries. We developed a general earthquake cycle model applicable to transform fault zones, subduction zones, and collision zones on the basis of elastic dislocation theory. In this model we regard the periodic occurrence of interplale earthquakes as a perturbation of the hypothetical steady slip motion proceeding on the whole plate boundary. Then the crustal deformation associated with the periodic occurrence of interplate earthquakes is given by the superposition of viscoelastic responses to the steady slip on the whole plate boundary, the steady back slip on the seismic zone, and the sequence of periodic seismic slips. The important points in this earthquake cycle model are as follows. Interaction between adjacent plates can be naturally represented by the increase of discontinuity in tangential displacement across the plate boundary. Viscoelastic stress relaxation of the asthenosphere strongly affects the crustal deformation during interseismic period. Since the stress relaxation time of the lithosphere-asthenosphere system is several hundreds years, we must consider the viscoelastic effects due to a series of large events occurred for the past several hundreds years to estimate crustal deformation correctly. Crustal deformation and stress accumulation due to steady slip on the whole plate boundary can not be neglected.

総合報告: 地震活動パターンと大地震の長期予測 -繰返し・空白域・静穏化・先行地震・移動・相関など-

Recent studies (1987 and later) of seismicity patterns presumably having some power to predict large earthquakes are reviewed. Here ‘large earthquakes’ mean relatively large earthquakes considered as objects of prediction. Seismic gaps (observed in the later half of the recurrence cycle) are useful in limited fault segments. Many examples of seismic quiescence (local or regional) have been reported, some of which were followed by large earthquakes and others were not. Migration patterns of seismic activity are very variable and mostly transient. There are some cases of close correlation between large earthquakes in two regions. The test of the statistical significance of a proposed pattern is often difficult due to uncertainty in evaluating the effect of selection of favorable data set. However, many of the patterns seem to be real and can be used in the long-term probabilistic prediction of large earthquakes. The probability of occurrence of a large earthquake after the appearance of one of the patterns discussed here is not easy to estimate. This is because of (1) many parameters which characterize the pattern and the target earthquake, (2) regional differences in the character of pattern, and (3) relatively few observational data on each pattern in each region.

Probable evidence for periodicities in global seismic energy release

A complete data set of globally distributed shallow (h ≤, 60 Km) earthquakes have been used for first time to test the possible existence of periodicities in the seismic energy release. Only main shocks of magnitude,M ≥ 7.0 were considered, which occurred in the whole Earth during 1898–1985. These magnitudes are converted in seismic energy, which is released during the occurrence of earthquakes, through Bath's formula. The detection of such kind of periodicities is important in seismology, because these patterns may lead to the prediction of large earthquakes. Statistical techniques, such as Maximum Entropy (ME), and two Fourier approaches, the Fast Fourier Transform (FFT) and Power Spectrum (PS) of truncated subrecords of the whole time series have been applied to examine the possible existence of such periodicities in seismic energy release. Furthermore, the even-spacing technique is used to validate our results and a type-curve has been constructed for the data set. The results exhibit a network of periodicities with predominant periods at 3(±0.5), 4.5, 6.5, 8–9, 14–20, and 31–34 years. Some periods were occasionally interrupted. The latter implies that our time-series is not stationary, in that, the spectral peaks drift when the data are viewed through different time windows. The fact that the signal is weak and embedded in less accurate older data could contribute to this effect. The question of stability/validity of the apparently cyclic behaviour of the annual global seismic energy release, is one which requires further investigation.

活断層の活動予測

The nature of active faults is reviewed to estimate future activity. Criteria for the prediction of large earthquakes are given based on active faults and some earthquake-expectancy maps are shown.The activity of active faults is of a cyclic nature. The cyclic consists of the following four stages : (1) A long-continued quiet period of very low seismicity. The length of this period differs with each fault on the order of 100 year to more than 10, 000 years. (2) A p ecursory seismic period of relatively high seismicity for several years (or longer) before the next stage. (3) A foreshock period of several weeks (or less). About half of the Japanese inland active faults, that moved in the last one hundred years, had remarkable felt-foreshock activity before the main shock. (4) An aftershock period. The magnitude of the seismicity of each stage and time-length of the cycle differ with each fault, but have been nearly constant at every fault or every fault segment during the late Quaternary.The following four criteria are used for estimating future large earthquakes, from which seismic zoning maps and strong ground motion frequency maps have been prepared : I. An active fault indicates the site of the future destructive earthquakes. II. Longer faults can produce larger earthquakes. III. Every fault has its own size of seismic slip (or earthquake magnitude) and recurrence interval. W. Large earthquakes tend to occur successively from segments in a fault zone.

Characteristics of foreshock activities associated with large shallow intraplate earthquakes in the Japanese islands.

Characteristics of foreshock activities before large shallow (M≥5, depth≤30km) earthquakes in and near the Japanese islands have been investigated. Of 110 main shocks which occurred during the period 1961 through 1988, 41, or 37 per cent, were preceded by foreshock sequences that included events within 30 days of the main shocks. The distance criterion for foreshocks is simply that it be within the 20′×20′ square centered on each main shock. The percentage of earthquakes with foreshocks scarcely changes if we take for criteria 40 days or 30′×30′ square. Last foreshocks most likely occur within a day before the main shocks in close proximity to their epicenters. In the period after 1981, foreshocks were observed for 55 per cent of large earthquakes, while the ratio was 27 per cent for the period 1961-1970, and 37 per cent for the period 1971-1980, which fact shows that hypocenter determination capability of the Japan Meteorological Agency has remarkably improved in recent years. Considerable regional characteristics exist in foreshock activity. One of them is that earthquakes in the Izu region and in Kyushu island are likely to be preceded by foreshocks. In particular, 67 per cent of earthquakes in and near the Izu Peninsula have foreshocks, as compared with only 26 per cent in other regions. Moreover, foreshock sequences in the Izu region and Kyushu island are often swarm-like in contrast to those in other regions which usually contain not more than a few shocks. In most cases the swarm-like foreshock activity in the Izu region becomes quiet two or three hours before the occurrence of the main shock. The phenomenon is considered to imply that stress relaxation occurs in the focal region due to nucleation of fracture just before the occurrence of a large earthquake. Regional characteristics of foreshock activities presented in this study are consistent with the results by Mogi (1963), in which foreshocks for moderate and large earthquakes in and around the Japanese islands during the period 1926 through 1961 were investigated, which fact indicates that the characteristics are intrinsic properties and stem from regional differences of crustal structure and stress accumulation system as pointed out early by Mogi (1963). Time sequences of foreshock activities are classified into 4 Types. Type 1 includes such cases that only one or a few earthquakes occur several to tens days before the main shock. Some events of this Type may not be directly connected to the main shock occurrence. In Type 2 cases one foreshock occurs as in Type 1, but immediately (usually within several minutes) before the main shock occurrence. Foreshocks of this Type may indicate the commencement of fracture which is succeeded by the occurrence of a main shock. Type 3 is represented typically by cases where a moderate earthquake with a magnitude of 4 or so occurs several hours to one day before the main shock, and its aftershocks, sometimes its foreshocks as well, are observed. This seismic activity associated with the moderate earthquake usually disappears a few hours before the main shock. Type 4 corresponds to swarm-like activity. Occurrence of Type 3 and Type 4 foreshock sequences is almost confined to the Izu region, the Fossa Magna area, and the central part of Kyushu island. The appearance of a quiescent period a few hours just before the occurrence of a main shock in Type 3 and in a part of Type 4 sequences, especially in the Izu region, is considered to be a prospective precursory phenomenon for the imminent prediction of large earthquakes.