Integration of geological and seismological data in earthquakes occurrence models for Italy: towards a unified model for different forecast perspectives

2019 ◽  
Vol 219 (3) ◽  
pp. 2148-2164
Author(s):  
A M Lombardi
Keyword(s):  
Aftershock Sequence ◽  
Earthquake Forecasting ◽  
Short Term ◽  
Background Rate ◽  
Etas Model ◽  
Term Forecast ◽  
Earthquake Predictability ◽  
Background Seismicity ◽  
Different Types

SUMMARY The operational earthquake forecasting (OEF) is a procedure aimed at informing communities on how seismic hazard changes with time. This can help them live with seismicity and mitigate risk of destructive earthquakes. A successful short-term prediction scheme is not yet produced, but the search for it should not be abandoned. This requires more research on seismogenetic processes and, specifically, inclusion of any information about earthquakes in models, to improve forecast of future events, at any spatio-temporal-magnitude scale. The short- and long-term forecast perspectives of earthquake occurrence followed, up to now, separate paths, involving different data and peculiar models. But actually they are not so different and have common features, being parts of the same physical process. Research on earthquake predictability can help to search for a common path in different forecast perspectives. This study aims to improve the modelling of long-term features of seismicity inside the epidemic type aftershock sequence (ETAS) model, largely used for short-term forecast and OEF procedures. Specifically, a more comprehensive estimation of background seismicity rate inside the ETAS model is attempted, by merging different types of data (seismological instrumental, historical, geological), such that information on faults and on long-term seismicity integrates instrumental data, on which the ETAS models are generally set up. The main finding is that long-term historical seismicity and geological fault data improve the pseudo-prospective forecasts of independent seismicity. The study is divided in three parts. The first consists in models formulation and parameter estimation on recent seismicity of Italy. Specifically, two versions of ETAS model are compared: a ‘standard’, previously published, formulation, only based on instrumental seismicity, and a new version, integrating different types of data for background seismicity estimation. Secondly, a pseudo-prospective test is performed on independent seismicity, both to test the reliability of formulated models and to compare them, in order to identify the best version. Finally, a prospective forecast is made, to point out differences and similarities in predicting future seismicity between two models. This study must be considered in the context of its limitations; anyway, it proves, beyond argument, the usefulness of a more sophisticated estimation of background rate, inside short-term modelling of earthquakes.

Ensembles of ETAS Models Provide Optimal Operational Earthquake Forecasting During Swarms: Insights from the 2015 San Ramon, California Swarm

2019 ◽  
Vol 109 (6) ◽  
pp. 2145-2158 ◽  
Author(s):  
Andrea L. Llenos ◽  
Andrew J. Michael
Keyword(s):  
Aftershock Sequence ◽  
Model Fit ◽  
Earthquake Forecasting ◽  
Ensemble Forecasts ◽  
Background Rate ◽  
Etas Model ◽  
Omori Law ◽  
Aftershock Sequences ◽  
Seismicity Rates ◽  
The Individual

Abstract Earthquake swarms, typically modeled as time‐varying changes in background seismicity, which are driven by external processes such as fluid flow or aseismic creep, present challenges for operational earthquake forecasting. Although the time decay of aftershock sequences can be estimated with the modified Omori law, it is difficult to forecast the temporal behavior of seismicity rates during a swarm. To explore these issues, we apply the epidemic‐type aftershock sequence (ETAS) model (Ogata, 1988) to the 2015 San Ramon, California swarm, which lasted several weeks and had almost 100 2≤M≤3.6 earthquakes. We develop three‐day forecasts during the swarm based on an ETAS model fit to all prior seismicity in the region as well as an ETAS model fit only to previous swarms in the region, which is better at capturing the higher background rate during the swarm. We also explore forecasts in which the background rate is updated periodically during the swarm using data over different lookback windows and find generally these models perform better than the models in which the background rate is fixed. Finally, we construct ensemble forecasts by combining the different models weighted according to their performance. The ensemble forecasts outperform all of the individual models and allow us to avoid making arbitrary choices at the outset of a swarm as to which single model will perform the best.

scholarly journals Short-term earthquake forecasting experiment before and during the L’Aquila (central Italy) seismic sequence of April 2009

2015 ◽  
Vol 57 (6) ◽  
Author(s):  
Maura Murru ◽  
Jiancang Zhuang ◽  
Rodolfo Console ◽  
Giuseppe Falcone
Keyword(s):  
Central Italy ◽  
Aftershock Sequence ◽  
Earthquake Forecasting ◽  
Model Parameters ◽  
Short Term ◽  
Productivity Function ◽  
Epidemic Type Aftershock Sequence ◽  
Forecasting Performance ◽  
The One ◽  
Lower Magnitude

<div class="page" title="Page 1"><div class="layoutArea"><div class="column"><p>In this paper, we compare the forecasting performance of several statistical models, which are used to describe the occurrence process of earthquakes in forecasting the short-term earthquake probabilities during the L’Aquila earthquake sequence in central Italy in 2009. These models include the Proximity to Past Earthquakes (PPE) model and two versions of the Epidemic Type Aftershock Sequence (ETAS) model. We used the information gains corresponding to the Poisson and binomial scores to evaluate the performance of these models. It is shown that both ETAS models work better than the PPE model. However, in comparing the two types of ETAS models, the one with the same fixed exponent coefficient (<span>alpha)</span> = 2.3 for both the productivity function and the scaling factor in the spatial response function (ETAS I), performs better in forecasting the active aftershock sequence than the model with different exponent coefficients (ETAS II), when the Poisson score is adopted. ETAS II performs better when a lower magnitude threshold of 2.0 and the binomial score are used. The reason is found to be that the catalog does not have an event of similar magnitude to the L’Aquila mainshock (M<sub>w</sub> 6.3) in the training period (April 16, 2005 to March 15, 2009), and the (<span>alpha)</span>-value is underestimated, thus the forecast seismicity is underestimated when the productivity function is extrapolated to high magnitudes. We also investigate the effect of the inclusion of small events in forecasting larger events. These results suggest that the training catalog used for estimating the model parameters should include earthquakes of magnitudes similar to the mainshock when forecasting seismicity during an aftershock sequence.</p></div></div></div>

USE OF REGRESSION ANALYSIS IN FORECAST TASKS

2020 ◽  
pp. 22-27
Author(s):  
E.S. Lartseva ◽  
◽  
A.D. Kuznetsova
Keyword(s):  
Regression Analysis ◽  
Animal Population ◽  
Short Term ◽  
Statistical Estimates ◽  
Term Forecast ◽  
Applied Software ◽  
The Family ◽  
The Russian Federation

Based on official statistics on the number, of representatives of the family of non-ruminant cloven-hoofed animals (Artiodactyl) on the territory of the Russian Federation. Using the example of two species: domestic pigs and wild boars, the dynamics of the indicator for the long term is analyzed. Multidirectional trends were revealed for each species. Mathematical models of the dynamics of the livestock were obtained using the methods of regression analysis and applied software. Statistical estimates of the quality of animal population models were obtained. The short-term forecast for 2020 has been fulfilled.

15. Democracies, Democratization, and Authoritarian Regimes

2020 ◽  
pp. 336-362
Author(s):  
Peter Ferdinand
Keyword(s):  
Economic Development ◽  
Recent Literature ◽  
Authoritarian Regimes ◽  
Short Term ◽  
National Crisis ◽  
Different Types ◽  
Types Of Democracy ◽  
The Face ◽  
Long Term Trends

This chapter focuses on democracies, democratization, and authoritarian regimes. It first considers the two main approaches to analysing the global rise of democracy over the last thirty years: first, long-term trends of modernization, and more specifically economic development, that create preconditions for democracy and opportunities for democratic entrepreneurs; and second, the sequences of more short-term events and actions of key actors at moments of national crisis that have precipitated a democratic transition — also known as ‘transitology’. The chapter proceeds by discussing the different types of democracy and the strategies used to measure democracy. It also reviews the more recent literature on authoritarian systems and why they persist. Finally, it examines the challenges that confront democracy in the face of authoritarian revival.

Statistical Monitoring and Early Forecasting of the Earthquake Sequence: Case Studies after the 2019 M 6.4 Searles Valley Earthquake, California

2020 ◽  
Vol 110 (4) ◽  
pp. 1781-1798 ◽  
Author(s):  
Yosihiko Ogata ◽  
Takahiro Omi
Keyword(s):  
Real Time ◽  
Case Studies ◽  
Seismic Activity ◽  
Southern California ◽  
Aftershock Sequence ◽  
Earthquake Sequence ◽  
Short Term ◽  
Probability Forecast ◽  
Background Rate ◽  
High Background

ABSTRACT This study considers the possible implementation of the operational short-term forecasting, and analysis of earthquake occurrences using a real-time hypocenter catalog of ongoing seismic activity, by reviewing case studies of the aftershocks of the Mw 6.4 Searles Valley earthquake that occurred before the Mw 7.1 Ridgecrest earthquake. First, the short-term prediction of spatiotemporal activity is required in real time along with the background seismic activity over a wide region to obtain practical probabilities of large earthquakes; snapshots from the continuous forecasts during the Searles Valley and Ridgecrest earthquake sequence are included to monitor the growth and migration of seismic activity over time. We found that the area in and around the rupture zone in southern California had a very high background rate. Second, we need to evaluate whether a first strong earthquake may be the foreshock for a further large earthquake; the rupture region in southern California had one of the highest such probabilities. Third, short-term probability forecast of early aftershocks are much desired despite the difficulties with data acquisition. The aftershock sequence of the Mw 6.4 Searles Valley event was found to significantly increase the probability of a larger earthquake, as seen in the foreshock sequence of the 2016 MJMA 7.4 Kumamoto, Japan, earthquake. Finally, detrending the temporal activity of all the aftershocks by stretching and shrinking the ordinary time scale according to the rate given by the Omori–Utsu formula or the epidemic-type aftershock sequence model, we observe the spatiotemporal occurrences in which seismicity patterns may be abnormal, such as relative quiescence, relative activation, or migrating activity. Such anomalies should be recorded and listed for the future evaluation of the probability of a possible precursor for a large aftershock or a new rupture nearby. An example of such anomalies in the aftershocks before the Mw 7.1 Ridgecrest earthquake is considered.

Operational Earthquake Forecasting during the 2019 Ridgecrest, California, Earthquake Sequence with the UCERF3-ETAS Model

2020 ◽  
Vol 91 (3) ◽  
pp. 1567-1578 ◽  
Author(s):  
Kevin R. Milner ◽  
Edward H. Field ◽  
William H. Savran ◽  
Morgan T. Page ◽  
Thomas H. Jordan
Keyword(s):  
High Performance ◽  
Aftershock Sequence ◽  
Lessons Learned ◽  
Ease Of Use ◽  
Earthquake Forecasting ◽  
Earthquake Rupture ◽  
Etas Model ◽  
Epidemic Type Aftershock Sequence ◽  
Aftershock Sequences ◽  
High Performance Computing Cluster

Abstract The first Uniform California Earthquake Rupture Forecast, Version 3–epidemic-type aftershock sequence (UCERF3-ETAS) aftershock simulations were running on a high-performance computing cluster within 33 min of the 4 July 2019 M 6.4 Searles Valley earthquake. UCERF3-ETAS, an extension of the third Uniform California Earthquake Rupture Forecast (UCERF3), is the first comprehensive, fault-based, epidemic-type aftershock sequence (ETAS) model. It produces ensembles of synthetic aftershock sequences both on and off explicitly modeled UCERF3 faults to answer a key question repeatedly asked during the Ridgecrest sequence: What are the chances that the earthquake that just occurred will turn out to be the foreshock of an even bigger event? As the sequence unfolded—including one such larger event, the 5 July 2019 M 7.1 Ridgecrest earthquake almost 34 hr later—we updated the model with observed aftershocks, finite-rupture estimates, sequence-specific parameters, and alternative UCERF3-ETAS variants. Although configuring and running UCERF3-ETAS at the time of the earthquake was not fully automated, considerable effort had been focused in 2018 on improving model documentation and ease of use with a public GitHub repository, command line tools, and flexible configuration files. These efforts allowed us to quickly respond and efficiently configure new simulations as the sequence evolved. Here, we discuss lessons learned during the Ridgecrest sequence, including sensitivities of fault triggering probabilities to poorly constrained finite-rupture estimates and model assumptions, as well as implications for UCERF3-ETAS operationalization.

Testing of the foreshock hypothesis within an epidemic like description of seismicity

2020 ◽  
Author(s):  
G Petrillo ◽  
E Lippiello
Keyword(s):  
Seismic Activity ◽  
Good Description ◽  
Aftershock Sequence ◽  
Short Term ◽  
Etas Model ◽  
Temporal Clustering ◽  
Epidemic Type Aftershock Sequence ◽  
Preparatory Phase ◽  
Spatio Temporal ◽  
The One

Summary The Epidemic Type Aftershock Sequence (ETAS) model provides a good description of the post-seismic spatio-temporal clustering of seismicity and is also able to capture some features of the increase of seismic activity caused by foreshocks. Recent results, however, have shown that the number of foreshocks observed in instrumental catalogs is significantly much larger than the one predicted by the ETAS model. Here we show that it is possible to keep an epidemic description of post-seismic activity and, at the same time, to incorporate pre-seismic temporal clustering, related to foreshocks. Taking also into-account the short-term incompleteness of instrumental catalogs, we present a model which achieves very good description of the southern California seismicity both on the aftershock and on the foreshock side. Our results indicate that the existence of a preparatory phase anticipating mainshocks represents the most plausible explanation for the occurrence of foreshocks.

Simple Techniques for Monitoring Footpath Erosion in Mountain Areas of North-West England

1977 ◽  
Vol 4 (2) ◽  
pp. 145-148 ◽  
Author(s):  
Rosalind A. Coleman
Keyword(s):  
Aerial Photography ◽  
Technical Expertise ◽  
Short Term ◽  
Mountain Areas ◽  
North West ◽  
Different Types ◽  
Different Seasons ◽  
One Year ◽  
Site Types

Very precise measurements of the movement of coarse-textured, unconsolidated materials may be meaningless. Therefore the study of individual processes operating on footpaths may require a different approach. However, for identification of changes of reasonable dimensions, methods such as those described above are inexpensive, quick, and require no technical expertise. It may be argued that, for path management, erosion that is too limited to be measured by these methods is too limited to be a problem. It can certainly be argued that the problem of spatial correlation implies a large number of measurements. What is lost in lack of precision may be more than compensated for by the gain in data from the larger area and wider variation in site-types that it is possible to monitor with such simple techniques.To monitor the effects of recreation in mountain areas, it is desirable to be able to measure any change in path-state and relate this to recreation factors at different seasons and under different sit; -conditions. Three methods of measurement have been considered in this paper, corresponding to three time-scales. Aerial photography has been used to demonstrate trends over the long term, and has proved adequate to differentiate between path sections with differing resistance to erosion.Short-term measurement has been carried out relative to known fixed positions. Two methods are suggested. One is less precise, but simple and widely applicable, and can be used for measurement intervals of six months to one year. The other is more detailed and can be used for measurement intervals of a few days, but is limited in its application by practical considerations.It is suggested that simple techniques used at a large number of different types of site may be more effective than detailed measurements at a few sites.

scholarly journals Terrorism as a type of political communication: The use of propaganda of the deed in hegemonic struggles

2020 ◽  
Vol 72 (4) ◽  
pp. 709-732
Author(s):  
Filip Otovic-Visnjic
Keyword(s):  
Political Communication ◽  
Communication Strategies ◽  
Important Goal ◽  
Short Term ◽  
Cultural Approach ◽  
Different Types ◽  
Theoretical Conception ◽  
Terrorist Acts ◽  
Efficient Realization

The paper focuses on the communicological dimension of the terrorist act, starting from the position that the violence is used to convey various messages in a non-verbal way. Throughout the research into the propaganda of the deed, the technique on which communicational tactics of terrorists are mostly based, the author seeks to examine extensive ranges of communication strategies used by insurgent groups against dominant hegemony. By combining the elements of Jacques Ellul's theoretical conception of propaganda along with the cultural approach in the interpretation of mechanisms in which hegemony operates, the author refutes perspectives that deny rebellions? possibilities for efficient realization of their propaganda goals by using acts of violence. The author?s conclusion is based on three arguments. Firstly, for modern propaganda, provoking the behavior of the audience (ortopraxie) is a more important goal than influencing its attitudes (orthodoxy). Secondly, it is possible to notice elements in the pre-propaganda field, which evade hegemonic control, due to the contradiction between ideological narratives and the real structure, and which insurgent propaganda may utilize. Lastly - by means of terrorist acts, their performers address different types of audiences with different goals simultaneously. The author concludes that the efficiency of propaganda can be manifested in two manners: in the short term - when an act of violence represents a direct ?trigger? for the desired behavior of the audience; in the long term - by including the act and provoked behavior in the network of memories, which becomes an element of pre-propaganda that can be referred to in the future.

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