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the last s2 dpc-Ingv project L. Peruzza1, F. Pacor2, A. Goretti3 (coord.)1 OGS – Istituto Nazionale di Oceanografia e di Geofisica Sperimentale, Trieste, Italy2 INGV – Istituto Nazionale di Geofisica e Vulcanologia, Milano, Italy3 DPC – Dipartimento Nazionale della Protezione Civile, Roma, Italy

Project S2 “Constraining Observations into Seismic Hazard” is the last S2 project funded in the frame of the 2012-2021 Agreement between DPC and INGV. It concerns the mid-long term Seismic Hazard Assessment in Italy, namely focusing on two priority areas, the Po Plain and peninsular Southern Italy. The planning and expected activities for the second and ultimate year S2-2014 (https://sites.google.com/site/ingvdpc2014progettos2/) are the continuation of S2-2012 Project, which results are available for the whole scientific community on a twin project’s website (https://sites.google.com/site/ingvdpc2012progettos2/).

The S2-2014 Project’s advances have been verified during quarterly meetings with the Joint Commission INGV-DPC (Commissione Paritetica INGV-DPC) organized in July and November, 2014, and in March and June, 2015; the mid-term report on activities was released in November 2014. A final report, organized in 3 sections, has been released after the final conference of all the DPC-INGV Seismological Program, held in Bologna on June 4-5, 2015;

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this note derives from it. All the documentations of intermediate phases (reports, presentations) are available for the whole scientific community, stored on the project’s website.

The specific objectives pursued by the both the 2012 and 2014 projects are:1. to develop a repository of probabilistic and deterministic seismic hazard assessments

(SHA);2. to carry out low-cost geophysical investigations based on active and passive techniques

on about 30-40 RAN accelerometric recording stations, improving the estimate of the soil response to earthquakes, through quantitative description of the shear wave velocity profile obtained from quantitative measurements;

3. to promote the use and the development of surface/borehole instruments to have a better site characterization;

4. to exploit the results of the soil response analysis to validate the soil classification at the accelerometric stations;

5. to update the ITACA and OASIS public databases with site information at accelerometric stations, collected in this project, to extend the use and improve the quality of the Italian strong motion data;

6. to provide extended seismic history of several recording sites of the Italian accelerometric network (RAN) in terms of macroseismic intensity and strong-motion parameters, to be used for validate the hazard studies;

7. to propose a methodology to evaluate intensity data points during long seismic sequences, taking into account the increasing buildings vulnerability;

8. to test different approaches to evaluate fully site-specific probabilistic hazard assessments, including site effects at local and regional scales;

9. to apply and develop innovative methods for PSHA in the Calabria region, including new seismotectonic models, interaction among faults and near source effects;

10. to validate and rank different PSHA studies, based on several qualified ground motion parameters;

11. to widen the case histories of induced seismicity in Italy, with prototypal data archives;12. to upgrade the analysis on seismic risk perception with statistically controlled surveys. The S2-2014 project was organized into 8 main Tasks, developed by activities proposals of

8 Research Units, as given in Tab. 1. The activities on liquefaction, implemented in Task 8 of the past S2-2012 project, have not

been continued in 2014-15, as similar activities were on-going under other agreements (DPC-Regione Emilia Romagna; DPC-Reluis 2013-2015).

Task 1 developed a repository usable for SHA analysis, including the SYNTHESIS database results of deterministic simulations of earthquake ruptures for major recent Italian earthquakes.

Task 2 has been devoted to the improvement of site-information at strong-motion recording stations. The aim was to correctly take into account the site responses for site-specific PSHA (Task 4) and provide proper data for the PSHA validation test (Task 6). These tasks involved most of the Project RUs (5 out of 8, see Tab. 1) and have been carried out in cooperation with other institutions and projects, e.g. DPC (GEORAN project), INGV and OGS institutional activities.

Task 3 developed some tools to integrate instrumental data with macroseismic observation, from the engineering perspective too.

The goals of Task 4 and Task 5 remained unchanged with respect to the S2-2012 Project. In Task 4 a major emphasis has been given to the evaluation of site response at municipal level, a fundamental ingredient for site-specific PSHA analysis and for correctly using the observed ground motions in the validations performed in Task 6. For this reason, a new research unit (RU8) has been involved on this topic, too.

For the importance of Task 6, devoted to the validation of the hazard studies, one more research unit (RU7) has been involved in the project.

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Given the growing attention on the induced seismicity, the activities of Task 7 have been increased and one more team (embedded in Research Unit RU3) has been added.

For Task 8, during the S2-2014 project, the DPC communication needs and strategies have been taken into account.

The project hosted also uncountable internal meetings, and three specific workshops; two of them marked the very beginning and very end of the project (DW1 - on “site-specific characterization” held in Milan, May 29, 2014, and DW3 - on “induced seismicity” in Rome, June 12, 2015); a restricted meeting on “aftershocks inclusion in seismic hazard” substituted an event originally planned on hazard validation, as an international workshop on the same topic was held by Eucentre in Pavia, in 2015.

Tab. 1 summarizes the research units involved and the theoretical funds allocation for each Task; all the research units have anticipated the funds. Up to now (September 28, 2015), the final submission of economic reports by the RUs reached about 70% of the total allocated budget of S2-2014, with ~253,000 out of 358,000 Euros.

It is worthwhile noticing the contemporaneous presence of different Research Units on some tasks: it implies a huge effort of coordination, as documented by the long list of meetings/appointments reported in the Project Agenda. Notably, all the Research Units and directors/DPC representative have worked in an agreed and cooperative manner, increasing the quantity and quality of results.

During the project some collaborations have been activated with other external projects and institutions that deal with similar issues. In particular, there were some interaction with other DPC-Reluis Projects (for instance, on the procedures relative to the deconvolution analysis, concerning risk perception and on the utilization of aftershocks in PSHA), with the Project GEORAN (DPC and CNR-IGAG) for the site characterization activity, again with the DPC Communication staff, for the risk perception topic, and with MiSE (Ministero dello Sviluppo Economico) and DPC for induced seismicity.

Tab. 1 - Tasks, RUs and funds assigned by the S2-2014 Project; funds are indicative as they have to be reimbursed on the basis of detailed expenses reports, due on Sept. 4, 2015.

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Spotlight on results. The S2-2014 Project produced 20 deliverables, the full list is given in Tab. 2. All the deliverables in format of report/electronic files have been released before the project end (June 30, 2015); some websites (e.g. Synthesis, ITACA, S2in, Nisbas) completed their upgrade during the summer.

Tab. 2 - Deliverables released by the S2-2014 Project; they are accessible from the web page https://sites.google.com/site/ingvdpc2014progettos2/deliverables or given as summaries in the Section 2 of the Final Report, at https://sites.google.com/site/ingvdpc2014progettos2/documents. Deliverables are reports, electronic files and websites, except those in the grey area that were meetings.

N

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

Task

1

1

2

2

2

2

3

3

4

4

4

5

6

7

8

8

8

2

5

7

Deliverable

D1.1 Earthquake Modelling collected by S2-2014

D1.2 Update of SYNTHESIS

D2.1 Site-specific characterization of selected ITACA stations

D2.2 Surface/borehole seismic data

D2.3 Ground motion variability of the stations selected for PSHA model validation

D2.4 Deconvolution analyses of newly characterized accelerometric sites

D3.1 Macroseismic and ground motion: site-specific conversion rules

D3.2 Macroseismic intensity accounting for vulnerability changes during seismic sequences

D4.1 Site-specific PSHA for previously selected sites

D4.2 Site-specific PSHA for newly selected sites, guidelines

D4.3 Site-response on true/virtual reference station

D5.1 Seismic hazard map in Southern Italy (revised)

D6.1 Validation of PSHA: methodological updates and new results

D7.1a On induced Seismicity in Italy: the new website “S2in”

D7.1b On induced seismicity in Italy: recent studies

D8.1 Questionnaire for risk perception (revised)

D8.2 Collected data in digital format

D8.3 Survey results

DW1 Site-characterization of accelerometric stations

DW2 Aftershocks in PSHA

DW3 On induced seismicity in Italy

Authors

D’Amico M., Maini C., Puglia R., Russo E., Pacor F., Luzi L.

idem

Luzi L., Felicetta C., Puglia R., Russo E., Pacor F., Maria M. D’Amico, Giovanni G. Lanzano and Task2 Working Group: Albarello D., Barani S., Barnaba C., Castellaro S., Gallipoli M.R., Laurenzano G., Massa M., Moscatelli M.

Mucciarelli M., Priolo E., Romanelli M., Laurenzano G., Garbin M., Stabile T.A., Gallipoli M.R., Martelli L.

Lanzano G., D’Amico M., Felicetta C., Luzi L., Puglia R., Pacor F.

Castellaro S., Albarello D.

Gomez Capera A.A., Locati M., Fiorini E., Bazzurro P., Luzi L., Massa M., Puglia R., Santulin M.

Grimaz S., Barazza F., Del Pin E., Malisan P.

Barani S., Spallarossa D.with contributions of ITACA and Task 2 Working Groups

idem

Laurenzano G., Priolo E., Barnaba C.

Akinci A., Burrato P., Tiberti M.M., Vannoli P., Mariucci M.T., Murru M., Falcone G., Taroni M., Herrero A., Spagnuolo E., D’Amico S.

Albarello D., Peruzza L., Goretti A. with contributions of RU7 EUCENTRE (Bazzurro P., Fiorini E.), ITACA team, and S2-2014 Task 2-4 Working Groups

Priolo E., Mucciarelli M., Laurenzano G., with contributions by: Caffagni E., Carannante S., Cattaneo M., D’Alema E., Frapiccini M., Gallipoli M., Garbin M., Ladina C., Marzorati, Monachesi G., and Stabile T.

Braun T., Buttinelli M., Caciagli M., Cattaneo M., Improta L., Marzorati S., Monachesi G., Piccinini D., Saccorotti G., Scrocca D.

Crescimbene M., La Longa F., Camassi R., Pino N.A., Pessina V., Cerbara L., Crescimbene C., Peruzza L.

idem

idem

RU 2 (INGV-MI) with contribution of S2 Directors & DPC Representative

S2 Directors & DPC Representative

RU 1 (OGS) with contribution of MiSE and S2 Directors & DPC Representative

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The results pertain to the fields of the probabilistic seismic hazard analysis related to the tuning and application of validation methods, the implementation of innovative methodologies to include site effects, the exploitation of detailed seismotectonic models, and the development and acquisition of new tools and data useful for seismic hazard. Finally, the project has promoted some activities related to induced seismicity and seismic risk perception, with potential significant implications regarding the seismic hazard reduction strategies.

The focus of the project was the validation exercise of Probabilistic Seismic Hazard Assessment (PSHA), started in S2-2012 project and continued within the Task 6 in 2014-15.

The scoring test completed during the S2-2012 Project highlighted the need of having: i) high quality site response characterizations for the accelerometric stations,ii) a careful check on completeness of recordings, not fully accomplished by the information

available in 2013 in the ITACA archive (http://itaca.mi.ingv.it), andiii) reinforced understanding of some methodological aspects of scoring.These issues have been addressed in this project and the validation exercise strongly

benefitted from the results obtained by the Task 2, Task 3 and Task 4. In particular, the adoption of site amplification inferred from the experimental data analysis

carried out within the Task 2, instead of the simplified NTC8 coefficients, has significantly changed the previous ranking results, highlighting the importance to have realistic amplification factors to correct the ground motion observed on soil categories different from rock condition. Furthermore, significant methodological improvements have been obtained taking into account the ground motion spatial correlation on seismic hazard estimate validation. This fact influences the validation test, too. In general the ground motion spatial correlation increases the variance of the variable used in the statistical test, and it makes more acceptable the ground motion observations.

Under Task 2, an extensive campaign of site characterization has been carried out, in synergy with the project GEORAN coordinated by CNR-IGAG and funded by DPC, in order to establish and apply the best practice for site characterization, following the standards in data acquisition and post-processing of the seismic microzonation defined at national level.

Among the 77 RAN stations, active since 1975 or at least continuously operating for 25 years, 46 sites have been investigated by different research units to provide detailed site-specific characterizations. All the collected data have been included (or, have being progressively included) in the ITACA database, increasing of about 50% the number of stations for which good geological and geophysical information is available. Notably, about 1/2 of the studied stations had changed their previously soil categories, assigned only on the basis of surface geology.

Innovative methodological approaches in PSHA have been proposed within Task 4 and Task 5, helping to clarify certain aspects still debated in the context of seismic hazard.

The Task 4 implemented and tested different methods (with increasing complexities) to introduce the local seismic response in PSHA at three sites (Mirandola, Casaglia and Soncino) that have been characterized in the context of the previous project. The PSHA for generic sites (Level 1), estimated considering the appropriate values of the site parameters (Vs30 or soil categories) in the Ground Motion Prediction Equations (GMPEs), performs quite well when compared to a more sophisticated approach (Level 4). Major problems can rise for sites that can have non-linear soil behaviour, or in case of shallow alluvium soil condition. The PSHA for generic site was then performed at the 77 RAN stations, exploiting the results obtained by Task 2. Thirteen different GMPEs were applied with the aim of examining the influence of differentGMPEs on the final hazard and evaluating improvements in ground motion prediction by thecomparison with observations at the single recording station.

Task 5 acquired new data and tested an alternative approach with respect to the standard model (MP04) for the Calabria region, reaching important results such as the development of a new seismotectonic model that allows the evaluation of earthquake probabilities for the largest

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events. Clustered and de-clustered catalogues have been also tested, showing that the former leads to increased ground motions in PGA at 10% exceedance probability in 50 years.

The development of tools and the data collection were accomplished within Task 1, Task 2 and Task 3 with the general goal of exploring the use of data of different nature, useful for hazard purposes. With the aim of promoting the use of synthetic seismograms as an alternative to strong-motion records, synthetic waveforms and input parameters were collected from previous deterministic simulations of past Italian seismic events; they have been validated through the comparison with recorded strong motions, and included in SYNTHESIS database (http://synthesis.mi.ingv.it/).

Once more under Task 2, a database, called NISBAS (Network of Italian Surface-Borehole Accelerometers and Seismometers) has been set-up, aimed at starting to fill a research gap related to coupled accelerometers at the surface and in borehole.

Within Task 3, various applications on macroseismic intensity data have been proposed. A web-tool, Rosetta, aims at linking intensity and strong motion data related to the same event in an interactive and innovative way. Some preliminary relationships between ground motion and macroseismic intensity are thus derived for the Italian territory. A joint effort between Task 3 and Task 6 has lead to analyses on spatial correlations applied to macroseismic fields, in order to derive some complementary information on completeness of accelerometric recordings. Attempts to evaluate intensity values during long seismic sequences have been also performed, analysing the cumulative damages on masonry buildings.

Task 7 promoted several activities on induced seismicity in Italy, mainly devoted to widen the knowledge of phenomena, not limited to the scientific audience, and to gather basic data sets that can be useful when treating anthropogenic seismic events. The activities culminated in a workshop, held in cooperation with DPC and MiSE whose materials are available for the whole community, from both the Task 7 and Project websites (http://www.sismicitaindotta.it/ and https://sites.google.com/site/ingvdpc2014progettos2/tasks/task/dw3-on-induced-seismicity-in-italy).

Last but not the least, in Task 8, devoted to risk perception, a survey questionnaire, initially developed under S2-2012 project, has been enhanced in order to take into consideration the building vulnerability, and to reach a wider, statistically significant sample of Italian citizens. The activity has benefitted from an additional economic contribution by INGV Roma 1 Section. The task presents a first analysis of the data and the comparison between the perceived risk and the “real risk” that can be a useful tool in targeting future campaigns to reduce seismic risk.

Lights, shadows and acknowledgements. The project S2 “Constraining observations into Seismic Hazard” has faced several difficulties and polemics during its accomplishment, culminated with the cut of one-year planning (applied to all the projects of the Seismological Programme which included S2, as well as to the projects of the twin Volcanological Programme), and changes of direction/evaluation/control criteria on the run. We believe they have been fixed, always giving priority to transparent choices, and to the interests of the whole Italian scientific community, that is facing heavy reductions in funds and human resources, and that more than ever now needs coordinated efforts and participated rules.

A true thorn in the flash of the project pertains to the administrative issues of working in anticipation of funds; they really impacted especially during the first phase of the project, and for the non-INGV research teams. At the moment we wrote this note (late Sept 2015, i.e. 2 months after the project end), the 1st tranche of funds has not been transferred yet. Conversely, we believe there was an excess of reports, with respect to the real needs of a research activity.

Concerning the lights, the project ended with a huge set of new data, new ideas, and new open issues, available for the whole scientific and non-scientific communities. Minutes and materials have been promptly made available on the Project website; it remains, with Skype sessions and mail messages, one of the favourite means of communication between the project’s participants. A posteriori, even if the number of users and sessions is not huge (see Fig. 1), the

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mean time spent on each session demonstrates some deepening in the contents, and the website is still attracting new visitors, in Italy and from abroad.

A special issue collecting selected papers from Tasks 1 to 6 has been proposed and accepted by an international journal (BEE - Bulletin of Earthquake Engineering); it is planned to be finished in late 2016. Conversely, Task 7 benefitted from a special issue of another international journal (BGTA – Bollettino di Geofisica Teorica ed Applicata), expected for late 2015. The results of Task 8 will follow other dissemination strategies, accordingly with the aims and needs of DPC Communication Office.

As conclusive remarks, we want to thank the project participants and all the other people that made it feasible. The motto, set-up at the very beginning of S2-2012 project in the website banner, states “Teamwork is the ability to work as a group toward a common vision, even if that vision becomes extremely blurry”. We feel it an appropriate auspice for the future development of research on seismic hazard assessment in Italy.

Acknowledgements. This study has benefited from funding provided by the Italian Presidenza del Consiglio dei Ministri – Dipartimento della Protezione Civile (DPC), Project S2-2014. This paper does not necessarily represent DPC official opinion and policies.

Fig. 1 – Web-site analysis: weekly number of page visualization and origin’s countries from the start of the S2-2014 project (May 1, 2014 – Sept 28, 2015).