UR dell'INGV

Objectives: Rapid field deployment of a new type of continuously operating Global Positioning System (GPS) network and data from Rete Integrata Nazionale GPS (RING) stations, that had recently begun operating in the area, allow unique observations of the postseismic deformation associated with the 2009 L'Aquila earthquake. Innovative solutions in field-craft, devised for the 5 new GPS stations, provide high-quality observations with 6-months time histories on stable monuments at remote sites. We propose to integrate the new 5 GPS sites temporary installed for the emergency into the RING in real time acquisition (Rinex 30s). Similarly, 5 seismic stations possibly with Nanometrics satellite-linked Real Time acquisition (satellite centre near Coppito, two near Montereale [RI] and 2 to the south) and few standalone stations are planned to be active for the project duration, to have precise locations of the earthquakes and monitor the segments adjacent to L'Aquila fault.

Activities: The activity include different steps as follows:

1. bureaucratic regularization of the survey sites to obtain environmental licenses;
2. opportune fence of enclosure protection;
3. power supply increase performance;
4. cable isolation get better;
5. wireless data connectivity improvements.

Methodology: GPS acquisition: within the framework of this project, we propose to acquire at 1-Hz in Real Time (and at 10 Hz in Local) sampling rate the data of the new 5 CGPS stations. These GPS data will be processed, by using Gipsy software, to analyze the temporal character and spatial pattern of the post-seismic and coseismic transients. The GPS Rinex file data will be will be available to the RING web site.

Seismic acquisition: seedLink server at Rome will acquire data from the Nanometrics satellite centre through the INGV NaqServer. Data will be published automatically in quasi real time whenever an earthquake with specified location and magnitude occurs. Data relative to the event will be grouped and put on the INGV web site (ISIDE database), for downloading by users. TDMT moment tensors and quick Regional CMT will be also published. Moreover it will be included in the SEED database.

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Objectives: Main goal of this working package is the creation of a waveform archive that will collect, in a SEED format (IRIS), the continuous recordings of the aftershock sequence of the Mw 6.3 L'Aquila earthquake. The archive will be formed by data recorded by INGV National Seismic Network and temporary station deployed by the INGV (CNT and CT); the stations installed by LGIT (Grenoble, France) are distributed in the same format by Grenoble.

Activities: To build the archive we should convert all the continuous seismic recordings (permanent stations, temporary stations) in a uniform Seed format. The data is stored in the original format on the mobile network data server MAYA, then it is going to be converted to SEED data format and fed to the HSL seedlink/arclink server.

Methodology: To build the archive we will take advantage of personnel, structures and experience of the National Seismic Network run by INGV that is doing it also for the Messina Strait Test site. We are developing standard procedure to convert all the gathered data in SEED format and to build a common open data-base for the researches.

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Responsible: The automatic and semi-automatic techniques developed in S5 project aimed at processing and analysing massive seismic data streams will be applied off-line to the 2009 L'Aquila earthquakes seismic waveform database. The waveform archives will consist of data recorded by the permanent strong motion networks of DPC and INGV and the by the temporary network installed to collect data from the aftershock sequence (WP4.2).
The methodologies will include the ones developed in (WP1.1) (Responsible Raffaele Di Stefano), (WP2.3) (Responsible Davide Piccinini), (WP3.2) (Responsible Claudio Satriano) and (WP2.5) (Responsible Giancarlo Neri). The final goal is to obtain refined estimates of main source parameters and crustal structure characteristics.

Activities: To build the archive we should convert all the continuous seismic recordings (permanent stations, temporary stations) in a uniform Seed format. The data is stored in the original format on the mobile network data server MAYA, then it is going to be converted to SEED data format and fed to the HSL seedlink/arclink server.

Methodology: To build the archive we will take advantage of personnel, structures and experience of the National Seismic Network run by INGV that is doing it also for the Messina Strait Test site. We are developing standard procedure to convert all the gathered data in SEED format and to build a common open data-base for the researches.

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Objectives: High-resolution (HR) seismic surveying is a powerful tool to investigate the shallow architecture of normal fault systems and related extensional basins. Detailed shallow imaging allows to define basin geometry and evolution, and to constrain fault geometry, dimension and recent behavior, which are fundamental information for a quantittive approach to seismic hazard assessment. For seismogenic sources, HR shallow profiling is crucial to link field observations to deep fault images obtained by earthquake data and/or industry reflection profiles. Actually, several studies testify the relevance of this approach at all stages of deterministic scenarios studies, from active fault characterization up to site effects evaluation (e.g. Pratt et al., 1998; Benjumea et al., 2003). This WP is devoted to the shallow crustal imaging (down to 500-1000 m depth) in the middle Aterno valley by HR surveying. Main targets are the Paganica seismogenic fault, nearby antithetic structures (Mt. Bazzano and Monticchio faults), and the related basins extending between the villages of Pianola, Monticchio and Paganica, where the maximum co-seismic subsidence as been observed (Atzori et al., 2009). Our primary goals are:

1. illuminating the shallow portion of the fault system;
2. reconstructing the basin geometry and evolution;
3. linking the source of the 6th April earthquake imaged by mainshock and aftershock recordings between 2-10 km depth (Chiarabba et al., 2009) to future morpho-structural and paleoseismological observations related to WP4.5 activity;
4. providing useful subsurface constraints for earthquake scenario and local site effects studies (faults and basin geometry, seismic velocity fields).

We propose to acquire two seismic profiles extending from Paganica to Bazzano and from Bazzano-Monticchio to Pianola, for a total length of about 7 km. Due to funding restrictions, if no other co-funding arises, we will collect only the first line, about 3.5 km long, and postpone the second line to future projects. Collaboration during this project is foreseen, not only with the Centre for Analysis and Monitoring of Environmental Risk (AMRA), but also with researchers of the Dept. of Structural Engineering of the University of Naples, that are planning seismic surveying to the west of L'Aquila, in the hangingwall of the Pettino fault.

Activities: Research activity includes different steps as follows:

1. surveys design according to logistic conditions and to the available morpho-structural and civil engineering borehole data. This activity will be performed in strict collaboration with DPC and with WP4.5;
2. acquisition of the HR profiles (total length of about 7 km);
3. Data editing and pre-processing;
4. determination of migrated stack sections by CDP-processing of reflection data;
5. first-arrival traveltime picking and tomographic inversion, model resolution assessment;
6. structural interpretation of the combined reflectivity and tomographic images (in collaboration with WP4.5);
7. preparation of input related fault and basin parameters of interest for earthquake scenario studies and local site effects analysis.

Methodology: A multi-channel acquisition device (216-channels, gathering instrumentation of the AMRA and of the INGV) will record shots provided by a vibroseis (IVI Minivib). We will use a non conventional multi-fold wide-aperture acquisition geometry (Ravaut et al., 2003). Dense sources (10 m interval) will be recorded by a geophones spread 1075 m wide (geophone interval 5 m). The use of a geophone spread 3-4 times larger than the expected thickness of the Quaternary infill, aims at investigating the entire basin structure, and related bounding normal faults, by both seismic reflection and tomographic techniques. Migrated stack sections will be determined by CDP- processing of HR reflection data through PROMAX routines (LandMark platform). Reflectivity images will be complemented by multi-scale velocity models obtained by non-linear first-arrival tomography. This integration allows the enhancement of geological interpretation and the improvement of reflection imaging by using the tomographic velocity field in the CDP-processing (Improta and Bruno, 2007). Preliminarily, we propose four possible line locations crossing the above-mentioned faults. Only after a careful recognition in the field and after the definition of the more interesting targets, we will able to identify the optimal location of the profiles.

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Objectives: The occurrence of the April 6 L'Aquila earthquake has highlighted how critical is the knowledge of the location and characteristics of the active faults in a seismic region. This is true not only as a contribution to the seismic hazard assessment but also for the local planning of residential areas, plants and infrastructures (Emergeo Working Group, 2009). The Paganica fault, responsible for this event, was already known in the literature (Bagnaia et al 1992; Vezzani e Ghisetti, 1998; Boncio et al. 2004; Foglio CARG 1:50,000 N. 359 L'Aquila) but no consideration of its activity was taken during the development of the area. In fact, besides the Gran Sasso aqueduct and the gas pipe crossing the Paganica fault, also many of the residential buildings along the fault escarpment were severely damaged because of the occurrence of surface faulting. On the other hand, knowing how large are the earthquakes these faults may produce, how fast they slip and how frequently they rupture are inputs needed for modern hazard assessment both at a local and regional scale.

The major aim of this WP is to produce a map of active faults of the broad area of the middle Aterno Valley that will represent a consensus document among the geologist operating in the area. This document will be a reference for future similar projects that will cover other portions of the national territory. This WP will also contribute to the discussion on the max Magnitude of the earthquakes these faults can produce and to the definition of their average frequency. This WP will be developed through a wide collaboration among researchers of INGV, ISPRA, CNR, DPC, and Universities that have experience in this area and on these specific topics. Collaboration is foreseen also with SIGRIS project, funded by ASI, that will develop paleoseismological trenching as a validation of deformation models built on interferometric data related to the LÕAquila earthquake sequence. All the results derived from this WP will be made available to other projects and in particular to S1.

Activities: Research activity includes different steps as follows:

1. analysis of the state of the art of the knowledge of active faults in the study area;
2. definition of the parameters describing the active faults and preparation of a GIS DB to host all the data;
3. review through field and aerial photo surveys of all the faults identified;
4. paleoseismological site selection along the Paganica and other faults, trenching, coring, and logging;
5. dating and paleoseismological interpretation;
6. input of all the fault related parameters in the GIS DB; Map preparation.

Methodology: Modern geological, geomorphological, stratigraphic, geocronological, and earthquake geology approaches will be at the basis of this WP. All the data will be integrated in a GIS DB. Because of the involvement of different groups, this WP may became a true reference for the development of future projects contributing in the knowledge of active fault distribution, to seismic hazard assessment at various scales, and to the surface faulting hazard.

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Objectives: The occurrence of large earthquakes like the recent L'Aquila event always represents a case study of critical importance for many aspects. Here, we focus our attention on how this experience has affected and may affect in the next future our skill in earthquake forecasting. Immediately after the L'Aquila earthquake, INGV researchers provided daily real-time forecasts of the seismic evolution of the aftershock sequence. The forecasts have been produced in the time- space-magnitude domain. To our knowledge this is the first time all around the world that such a real-time forecast has been made during an emergency. Goodness-of-fit tests performed after one month confirmed the good fit between forecasts and observations. Despite the success, the L'Aquila earthquake experience has brought in light many issues that we need to face in the next future to improve and optimize our forecasting capability. These issues span from technical to scientific domains. Among many issues, one main scientific point is the possibility to improve the performances of forecasting models.

As a matter of fact, the stochastic ETES (Epidemic-Type Earthquake Sequence) model used to forecast the evolution of the aftershock sequence is mostly based on simple physical components such as a constant tectonic seismic background and a symmetric in space co-seismic triggering. All information coming from geology, deformation monitoring and other observables are not included at this stage.

Here, we aim at exploring the possibility to improve the forecasting capability through a generalization of the available stochastic models (such as the ETES). In particular, we plan to investigate how to incorporate other components coming from physics, geology, and from the monitoring system. The timeline of this initiative is limited, therefore we cannot guarantee any practical results in this time frame. At this level our efforts will be devoted to produce a feasibility study for further researches in this field.

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MAIN REFERENCES

Atzori, S., Hunstad I., Chini M., Salvi S., Tolomei C., Bignami C., Stramondo S., Trasatti E., Antonioli A., Boschi E. (2009) - Finite fault inversion of DInSAR coseismic displacement of the 2009 L'Aquila earthquake (central itly), Geophys. Res. Lett., Vol. 36, No. 15, L15305, http://dx.doi.org/10.1029/2009GL039293.

Bagnaia, R., D'Epifanio A., Sylos Labini S. (1992) - Aquila and subaequan basins: an example of Quaternary evolution in Central Apennines, itly. Quaternaria Nova, II, 187-209. Boncio, P., Lavecchia G., Pace B. (2004) - Defining a model of 3D seismogenic sources for Seismic Hazard Assessment applications: the case of central Apennines (itly). Journal of Seismology, 8/3, 407-425.

Benjumea, B., Hunter J.A., Aylsworth J.M., Pullan S.E. (2003) - Application of high-resolution seismic techniques in the evaluation of earthquake site response, Ottawa Valley, Canada. Tectonophysics, 368, 1-4, 193-209.

Chiarabba C., P. De Gori, E. Boschi (2009) - Pore-pressure migration along a normal-fault system resolved by time-repeated seismic tomography, Geology 2009 v. 37, p. 67-70.

Chiarabba, C., et al., (2009b) - The 2009 L'Aquila (central itly) MW6.3 earthquake: main shock and aftershocks, Geophys. Res. Lett. (in press).

Emergeo Working Group (2009) Ð Field geological Survey in the epicentral area of the Abruzzi (central itly) seismic sequence of April 6, 2009, Quaderni di Geofisica, 70,INGV, Rome. Foglio CARG 1:50,000 (2009) - Cartografia geologica ufficiale Foglio CARG 1:50,000 N. 359, L'Aquila.

Improta L. and Bruno P.P (2007) - Combining seismic reflection with multifold wide-aperture profiling: An effective strategy for high-resolution shallow imaging of active faults, Geophys. Res. Lett., 34, L20310, doi:10.1029/2007GL031893.

Pratt, T.L, Dolan J.F., Odum J.K., Sthephenson W.J., Williams R.A., Templeton M.E. (1998) - Multiscale seismic imaging of active fault zones for hazard assessment : A case study of the Santa Monica fault zone, Los angeles, California, Geophysics, 63, 22, 479-489.

Ravaut, C., S. Operto, L. Improta, J. Virieux, A. Herrero, P. Dell'Aversana (2004) Ð Multiscale imaging of complex structures from multi-fold wide-aperture seismic data by frequency-domain full- waveform inversion: application to a thrust belt, Geophysical Journal International, 159, pp.1032- 1056.

Vezzani, L. and Ghisetti, F. (1998) - Carta Geologica dell'Abruzzo, scale 1:100,000, S.EL.CA., Firenze.

Zhu, L., Helmberger, D., 1996 - Advancement in source estimation technique using broadband regional seismograms, Bull. Seism. Soc. Amer. 86, 1634-1641.

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Task 4 Objectives

Staff