Applying the Disruption Index procedure to evaluate the urban seismic risk in the Mt. Etna area (Italy)

The Disruption Index is used here for the assessment of urban disruption in the Mt. Etna area after a natural disaster. The first element of the procedure is the definition of the seismic input, which is based on information about the historical seismicity and seismogenic faults. The second element is the computation of the seismic impact on the building stock and infrastructure in the region considered. Information on urban-scale vulnerability was collected and a geographic information system was used to organize the data relating to buildings and network systems (e. g., typologies, schools, strategic structures, lifelines). The central idea underlying the definition of the Disruption Index is the identification and evaluation of the impacts on a target community, considering the physical elements that contribute most to the severe disruption. The results of this study are therefore very useful for earthquake preparedness planning and for the development of strategies to minimize the risks from earthquakes. This study is a product of the European “Urban Disaster Prevention Strategies using Macroseismic Fields and Fault Sources” project (UPStrat-MAFA European project 2013).PublishedTorino, Italy3T. Pericolosità sismica e contributo alla definizione del rischioope

On assessing importance of components in dysfunction urban systems given an earthquake: the case of Mt. Etna region

Mt Etna region (Sicily, Italy) is one of the test areas studied in the European Project “Urban disaster Prevention Strategies using MAcroseismic fields and FAult sources” ( UPStrat-MAFA) to which the methodology of Disruption Index (hereafter DI), recently developed to evaluate the dysfunction of urban systems caused by earthquakes (Ferreira et al., 2014), has been applied on a trial basis

Particle filtering for continuous-time hidden Markov models

International audienc

Is space-time interaction real or apparent in seismic activity?

It is widely shared opinion that not only secondary (aftershocks) but also main earthquakes have the tendency to occur in space-time clusters. This assumption has affected the preferential choice of stochastic models in the studies on seismic hazard, like self-exciting (epidemic) models which imply the abrupt increase of the occurrence probability after a shock and the subsequent exponential decrease without the desirable increase before a forthcoming event. The importance of this assumption requires the application of statistical tools to evaluate objectively its coherence with the reality at different scale of magnitude-space-time. To this end we consider the earthquakes drawn from the historical Italian catalogue CPTI04 that geologists have associated with each of the eight tectonically homogeneous regions in which Italian territory is divided. Fixing different magnitude thresholds we perform statistical tests based on the space-time distance between pairs of earthquakes under the null hypothesis of uniform distribution in time and space and evaluate the significance of the possible clusters. Monte Carlo hypothesis testing is also used to obtain the null distribution and the simulated p-value

Productivity within the ETAS seismicity model

The productivity of a magnitude $m$ event can be characterized in term of triggered events of magnitude above $m-\Delta$: it is the number of direct "descendants" $\nu_\Delta$ and the number of all "descendants" $V_\Delta$. There is evidence in favour of the discrete exponential distribution for both $\nu_\Delta$ and $V_\Delta$ with a dominant magnitude $m$ (the case of aftershock cluster). We consider the general Epidemic Type Aftershock Sequence (ETAS) model adapted to any distribution of $\nu_\Delta$. It turns out that the branching structure of the model excludes the possibility of having exponential distributions for both productivity characteristics at once. We have analytically investigated the features of the $V_\Delta$ distribution within a wide class of ETAS models. We show the fundamental difference in tail behavior of the $V_\Delta$-distributions for general-type clusters and clusters with a dominant initial magnitude: the tail is heavy in the former case and light in the latter. The real data demonstrate the possibilities of this kind. This result provides theoretical and practical constraints for distributional analysis of $V_\Delta$.Comment: Corresponding author: George Molchan (email: [email protected]), 22 pages, 2 figures, submitted to Geophysical Journal Internationa

Deliverable Report of Task B of the European project UPStrat-MAFA - Deliverable/Task Leader: CNR-IMATI

DESCRIPTION OF TASK B The Task B “Probabilistic analysis of macroseismic data to forecast damage scenarios” includes the following seven Actions: Action B.1 Setting-up of aWorking Group on the macroseismic database (INGV); Action B.2 Exploratory analysis of macroseismic fields for their clustering in classes of attenuation decay (CNR-IMATI); Action B.3 Estimation of the probability distribution of the site-intensity Is , given epicentral intensity and distance from epicentre (isotropic case) (CNR-IMATI); Action B.4 Exploratory analysis of observed and synthetic macroseismic fields for their clustering in classes of anisotropic attenuation decay (CNR-IMATI); Action B.5 Estimation of the probability distribution of the site-intensity Is , given epicentral intensity and distance from epicentre (anisotropic case) (CNR-IMATI); Action B.6 Application of scoring rules (CNR-IMATI); Action B.7 Probabilistic analysis of macroseismic data using the logistic model (INGV) This report is basically divided into two parts. The former (Chapter I) deals with the methodological aspects of the Actions B2 - B6; it describes a clustering procedure to select classes of macroseismic fields with similar attenuation trend within a database, it proposes a probability model and an estimation method to evaluate the distribution of the intensity at site in both isotropic and anisotropic cases, and finally it presents three validation criteria by which to compare observed and estimated intensity at sites. The latter part of the report (Chapters II - V) focuses on the results obtained and provides solutions to specific issues arosen in applying the above-mentioned methods to the test areas considered in the project (Mt. Etna (Italy), Portugal and Azores Islands, Alicante-Murcia (Spain), Iceland). In addition to the collection of the data related to the test areas, Action B1 has also dealt with the digitalization in a GIS of isoseismal images drawn from the literature, and related to two historical earthquakes occurred in North Iceland (Chapter V). Action B7 was planned to compare the beta-binomial probability model analyzed in the project with the other probability model (logistic model) for the seismic attenuation given in the literature. The discussions had with the partners during the course of the project led us to prefer the comparison with the deterministic attenuation relationships currently used in the hazard evaluation of the test areas. The results of these comparisons are illustrated in Deliverable B6.1.The research was co-financed by EU-Civil Protection Financial Instrument (Grant Agreement n. 230301/2011/613486/SUB/A5)Unpublished3T. Pericolosità sismica e contributo alla definizione del rischioope