Intermediate-term narrow-range earthquake forecasting: an interdisciplinary tool based on seismological and geodetic observations

2020 ◽  
Author(s):  
Antonella Peresan ◽  
Mattia Crespi ◽  
Federica Riguzzi ◽  
Vladimir Kossobokov ◽  
Giuliano F. Panza
Keyword(s):  
Narrow Range ◽  
Central Italy ◽  
Earthquake Forecasting ◽  
Time Dependent ◽  
Strain Accumulation ◽  
Seismicity Patterns ◽  
Middle Range ◽  
Cn Algorithm ◽  
Velocity Variations ◽  
Italian Territory

<p>A novel forecasting tool, able to fully exploit the information content of the available data, is proposed for the synergic use of seismological and geodetic information, in order to delineate, at the intermediate-term narrow-range, the regions where to concentrate prevention actions and seismic risk mitigation planning. An application of the proposed interdisciplinary procedure, defining a new paradigm for time dependent hazard assessment scenarios, is exemplified illustrating its application to the Italian territory.</p><p>From seismological viewpoint, long-lasting practice and results obtained for the Italian territory in two decades of rigorous prospective testing of fully formalized algorithms (e.g. CN), proved the feasibility of earthquake forecasting based on the analysis of seismicity patterns at the intermediate-term (i.e. several months) middle-range scale (i.e. few hundred kilometers). An improved but not ultimate precision can be achieved reducing as much as possible the space-time volume of the alarms, by jointly considering seismological and geodetic information. In the proposed scheme geodetic information (i.e. GNSS and SAR) are used to reconstruct the velocity and strain pattern along transects properly oriented according to the a priori known tectonic and seismological information. Specifically, considering properly defined transects within the regions monitored by CN algorithm, the possible velocity variations and the related strain accumulation can be highlighted, with due consideration of the errors involved in GNSS data.</p><p>Through a refined retrospective analysis, duly involving the accuracy analysis of the newly available geodetic results, space­time precursory features could be highlighted within ground velocities and seismicity, analyzing the 2016-2017 seismic crisis in Central Italy and the 2012 Emilia sequence. The analysis, including counter examples, evidenced reliable anomalies in the strain rate distribution in space, whereas no time dependence was detected in the long term (more than 10 years) preceding the occurrence of the studied events.</p><p>With these results acquired, a systematic analysis of velocity variations (together with their accuracy) is performed, by defining a set of transects uniformly distributed, as far as possible, along and across major seismotectonic features of the Italian region, with a spacing of about 40-50 km and properly covering the regions monitored by CN algorithm. As a rule most of the transects contain information that appear to be useful for earthquake forecasting purposes. The few exceptions, naturally connected with the local very limited extension of land, are in Calabria and Western Sicily.</p><p>The obtained results show that the combined analysis of the results (time dependent within decadal interval) of intermediate-term middle-range earthquake prediction algorithms, like CN, with those from the processing of adequately dense and permanent GNSS network data (time independent within the same decadal interval), may allow to highlight in advance the localized strain accumulation. Accordingly the extent of the alarmed areas, identified based on seismicity patterns at the intermediate scale can be significantly reduced (from few hundred to few tens kilometres).</p>

scholarly journals Assessing ‘alarm-based CN’ earthquake predictions in Italy

2017 ◽  
Vol 59 (6) ◽  
Author(s):  
Matteo Taroni ◽  
Warner Marzocchi ◽  
Pamela Roselli
Keyword(s):  
Earthquake Prediction ◽  
News Media ◽  
Poisson Model ◽  
Prediction Performance ◽  
Testing Procedures ◽  
Earthquake Predictability ◽  
Forecast Models ◽  
Earthquake Predictions ◽  
Cn Algorithm ◽  
Italian Territory

<p>The quantitative assessment of the performance of earthquake prediction and/or forecast models is essential for evaluating their applicability for risk reduction purposes. Here we assess the earthquake prediction performance of the CN model applied to the Italian territory. This model has been widely publicized in Italian news media, but a careful assessment of its prediction performance is still lacking. In this paper we evaluate the results obtained so far from the CN algorithm applied to the Italian territory, by adopting widely used testing procedures and under development in the Collaboratory for the Study of Earthquake Predictability (CSEP) network. Our results show that the CN prediction performance is comparable to the prediction performance of the stationary Poisson model, that is, CN predictions do not add more to what may be expected from random chance.</p>

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>

scholarly journals Co-circulation of SARS-CoV-2 variants B.1.1.7 and P.1

2021 ◽  
Author(s):  
Paola Stefanelli ◽  
Filippo Trentini ◽  
Giorgio Guzzetta ◽  
Valentina Marziano ◽  
Alessia Mammone ◽  
...  
Keyword(s):  
Confidence Intervals ◽  
Immune Evasion ◽  
National Level ◽  
Central Italy ◽  
Cross Protection ◽  
Clinical Samples ◽  
Ecological Interactions ◽  
The World ◽  
National Prevalence ◽  
Italian Territory

SARS-CoV-2 variants of concern (B.1.1.7, P.1 and B.1.351) have emerged in different continents of the world. To date, little information is available on their ecological interactions. Based on two genomic surveillance surveys conducted on February 18 and March 18, 2021 across the whole Italian territory and covering over 3,000 clinical samples, we found significant co-circulation of B.1.1.7 and P.1. We showed that B.1.1.7 was already dominant on February 18 in a majority of regions/autonomous provinces (national prevalence 54%) and almost completely replaced historical lineages by March 18 (dominant in all regions/autonomous provinces, national prevalence 86%). At the same time, we found a substantial proportion of cases of the P.1 lineage on February 18, almost exclusively in Central Italy (with an overall prevalence in the macro-area of 18%), which remained at similar values on March 18, suggesting the inability by this lineage to outcompete B.1.1.7. Only 9 cases from variant B.1.351 were identified in the two surveys. At the national level, we estimated a mean relative transmissibility of B.1.1.7 (compared to historical lineages) ranging between 1.55 and 1.57 (with confidence intervals between 1.45 and 1.66). The relative transmissibility of P.1 estimated at the national level varied according to the assumed degree of cross-protection granted by infection with other lineages and ranged from 1.12 (95%CI 1.03-1.23) in the case of complete immune evasion by P.1 to 1.39 (95%CI 1.26-1.56) in the case of complete cross-protection. These observations may have important consequences on the assessment of future pandemic scenarios. 

scholarly journals b-value of what? Complex behavior of the magnitude distribution during and within the 2016–2017 central Italy sequence

2022 ◽  
Author(s):  
Marcus Herrmann ◽  
Ester Piegari ◽  
Warner Marzocchi
Keyword(s):  
Relative Rate ◽  
Central Italy ◽  
B Value ◽  
Earthquake Forecasting ◽  
Earthquake Catalog ◽  
Spatiotemporal Variations ◽  
Earthquake Occurrence ◽  
Tectonic Structures ◽  
Magnitude Distribution ◽  
Large Earthquakes

Abstract The Magnitude–Frequency-Distribution (MFD) of earthquakes is typically modeled with the (tapered) Gutenberg–Richter relation. The main parameter of this relation, the b-value, controls the relative rate of small and large earthquakes. Resolving spatiotemporal variations of the b-value is critical to understanding the earthquake occurrence process and improving earthquake forecasting. However, this variation is not well understood. Here we present unexpected MFD variability using a high-resolution earthquake catalog of the 2016–2017 central Italy sequence. Isolation of seismicity clusters reveals that the MFD differs in nearby clusters, varies or remains constant in time depending on the cluster, and features an unexpected b-value increase in the cluster where the largest event will occur. These findings suggest a strong influence of the heterogeneity and complexity of tectonic structures on the MFD. Our findings raise the question of the appropriate spatiotemporal scale for resolving the b-value, which poses a serious obstacle to interpreting and using the MFD in earthquake forecasting.

Relation of Time-Varying Vp/Vs ratio to Inflation and Deflation Episodes near Hengill Volcano, Iceland

2020 ◽  
Author(s):  
Ari Tryggvason ◽  
Alex Hobé ◽  
Olafur Gudmundsson ◽  
Halldor Geirsson ◽  
Keyword(s):  
Ground Deformation ◽  
Source Region ◽  
Compressible Fluids ◽  
Time Dependent ◽  
The North ◽  
New Information ◽  
Velocity Variations ◽  
Satellite Radar ◽  
Velocity Changes ◽  
Similar Area

&lt;p&gt;The Hengill area experienced an intensive and long-lived series of earthquakes in the 1990s. This coincided with a period of inflation near the Hengill volcano, which was interpreted as new influx of magma at ~7 km depth. Feigl et al. (2000) postulated that the observed seismicity was triggered by the strain accumulation associated with the magma-influx. In a similar area ~3 km to the NW, subsidence has been occurring since 2006. The timing of this subsidence coincides with the onset of geothermal production at Hellisheidi in the west and enlargement of the Nesjavellir powerplant in the North. The source of the subsidence near Hengill volcano is however estimated between 5.6 and 7 km depth and at significant lateral distances from these production sites (Juncu et al. 2016). In this study we apply newly developed methods in time-dependent seismic tomography (Hob&amp;#233; et al. 2020) in the Hengill area, to study if significant velocity changes can be attributed to these inflation/deflation episodes. The dataset employed for the tomography covers the inflation period, the subsidence period, and the time in-between, with varying station coverage and geometry. In this study, the artificial velocity variations due to variations in source and receiver geometries are first separated from &amp;#8220;true&amp;#8221; velocity variations. In the approximate source region of the 2006-onwards deflation the preliminary results show a low Vp/Vs ratio anomaly between ~4-7 km depth, with an EW extent of ~8-10 km and an NS extent of ~4 km. This anomaly coincides with a significant amount of seismicity. This may indicate an increase in the amount of compressible fluids, accompanied with hydro-fracturing. The seismicity terminates below this low Vp/Vs anomaly, underneath which there is an area of increased Vp/Vs ratios (associated with melt) in the approximate center of the inflation episode in the 1990s. Thus, this investigation provides new information about the nature of the deformation sources, and the surrounding hydrothermal system. We will further investigate the apparent connection between the current subsidence and geothermal production.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;References:&lt;/p&gt;&lt;p&gt;Feigl et al. (2000): Crustal deformation near Hengill volcano, Iceland 1993-1998: Coupling between magmatic activity and faulting inferred from elastic modeling of satellite radar interferograms, J. Geophys. Res.&lt;/p&gt;&lt;p&gt;Hob&amp;#233; et al. (2020): Imaging the 2010-2011 inflationary source at Krysuvik, SW Iceland, using time-dependent Vp/Vs tomography, WGC 2020, forthcoming&lt;/p&gt;&lt;p&gt;Juncu et al. (2016): Anthropogenic and natural ground deformation in the Hengill geothermal area, Iceland, J. Geophys. Res.&lt;/p&gt;

scholarly journals Importance of three-dimensional grids and time-dependent factors for applications of earthquake forecasting models to subduction environments

2016 ◽  
Vol 16 (9) ◽  
pp. 2177-2187 ◽  
Author(s):  
Chung-Han Chan
Keyword(s):  
Three Dimensional ◽  
Large Earthquake ◽  
Earthquake Forecasting ◽  
Time Dependent ◽  
Time Dependency ◽  
Seismicity Rate ◽  
Forecasting Models ◽  
Seismogenic Structures ◽  
Depth Dependency

Abstract. This study provides some new insights into earthquake forecasting models that are applied to regions with subduction systems, including the depth component for forecasting grids and time-dependent factors. To demonstrate the importance of depth component, a forecasting approach, which incorporates three-dimensional grids, is compared with an approach with two-dimensional cells. Through application to the two subduction regions, Ryukyu and Kanto, it is shown that the approaches with three-dimensional grids always demonstrate a better forecasting ability. I thus confirm the importance of depth dependency for forecasting, especially for applications to a subduction environment or a region with non-vertical seismogenic structures. In addition, this study discusses the role of time-dependent factors for forecasting models and concludes that time dependency only becomes crucial during the period with significant seismicity rate change that follows a large earthquake.

scholarly journals Analysis of precursory seismicity patterns in Zagros (Iran) by CN algorithm

2014 ◽  
Vol 23 ◽  
pp. 91-99 ◽  
Author(s):  
Majid MAYBODIAN ◽  
Mehdi ZARE ◽  
Hosseyn HAMZEHLOO ◽  
Antonella PERESAN ◽  
Anooshiravan ANSARI ◽  
...  
Keyword(s):  
Seismicity Patterns ◽  
Cn Algorithm ◽  
Precursory Seismicity

Paleozoic metasomatism at the origin of Mediterranean ultrapotassic magmas: Constraints from time-dependent geochemistry of Colli Albani volcanic products (Central Italy)

Lithos ◽  
2016 ◽  
Vol 244 ◽  
pp. 151-164 ◽  
Author(s):  
Mario Gaeta ◽  
Carmela Freda ◽  
Fabrizio Marra ◽  
Ilenia Arienzo ◽  
Fernando Gozzi ◽  
...  
Keyword(s):  
Central Italy ◽  
Time Dependent ◽  
Colli Albani

scholarly journals Lithological and stress anisotropy control large-scale seismic velocity variations in tight carbonates

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
F. Trippetta ◽  
M. R. Barchi ◽  
E. Tinti ◽  
G. Volpe ◽  
G. Rosset ◽  
...  
Keyword(s):  
Environmental Conditions ◽  
Large Scale ◽  
Seismic Velocity ◽  
Central Italy ◽  
Active Regions ◽  
Mineralogical Composition ◽  
Mountain Range ◽  
Seismic Velocities ◽  
Environmental Controls ◽  
Velocity Variations

AbstractOur knowledge of subsurface structures often derives from seismic velocities that are measured during seismic acquisition surveys. These velocities can greatly change due to lithological, fracture frequencies and/or effective pressure/temperature variations. However, the influence of such intrinsic lithological properties and environmental conditions at the large scale is poorly understood due to the lack of comprehensive datasets. Here, we analyze 43 borehole-derived velocity datasets of 3 end-member tight carbonate sequences from Central Italy, including massive pure limestone (Calcare Massiccio, CM), thick-layered (20–50 cm) pure limestone (Maiolica, MA), and thin-layered (2–20 cm) marly limestone (Calcareous Scaglia, CS). Our results show that the main rock parameters and environmental conditions driving large scale velocity variations are bedding and paleostresses, while mineralogical composition and current tectonic stress also play a role. For each of the 3 end-members, measured VP values vary differently with depth, as the thin-layered CS units show a clear increase in Vp, while velocity slightly increases and remains constant for the thick-layered MA and massive CM units, respectively. Such observations show that velocities are affected by specific characteristics of lithological discontinuities, such as the thickness of bedding. Counterintuitively, larger Vp values were recorded in the deformed mountain range than in the undeformed foreland suggesting that higher paleo-stresses increase velocity values by enhancing diagenesis and healing of discontinuities. Our results thus demonstrate that large scale velocity variations are strictly related to variation of lithological properties and to the geological and tectonic history of an area. We suggest that such lithological and environmental controls should be taken into account when developing velocity and mechanical models for tectonically active regions of the Mediterranean Area, where earthquakes mostly nucleate and propagate through carbonate formations, and for resource exploration in fractured carbonate reservoirs.

scholarly journals An Econometric Model for the Analysis of the Influence of the Refurbishment Costs on Housing Prices

2022 ◽  
Vol 19 ◽  
pp. 414-420
Author(s):  
P. Morano ◽  
F. Tajani ◽  
F. Di Liddo ◽  
M. Locurcio ◽  
D. Anelli
Keyword(s):  
Unit Cost ◽  
Housing Prices ◽  
Central Italy ◽  
Explanatory Variables ◽  
Functional Relationships ◽  
Residential Units ◽  
Italian Context ◽  
Econometric Technique ◽  
Italian Territory

With reference to the Italian context, the present research intends to analyze the functional relationships between the unit cost of restructuring and the selling prices in the residential segment. The analysis has been contextualized to the three clusters (Northern Italy, Central Italy, Southern Italy and Islands) in which the Italian territory is commonly divided. The case study concerns 965 residential units sold in the first half of 2019 and located in the 103 provincial capitals. The implemented econometric technique is a data-driven method that employs a genetic algorithm and allows the identification of the most influencing factors among the explanatory variables considered. For each cluster, a model has been selected in order to study the influence of unit cost of restructuring on housing prices.

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