vai al contenuto della pagina vai al menu di navigazione
 

Physics of the Earth

Research activities address a broad set of physical phenomena occurring in the solid and liquid Earth, which in particular are research objects of studies in Seismology, Physics of Volcanism, Geodesy and Oceanography. These research activities are designed to enhance and develop, in an integrated way, the knowledge on the state and the dynamics of the Earth System. They are also propaedeutic to the formulation of guidelines useful for the assessment and mitigation of related natural hazards.

Within the seismological field, the studies of the seismic source Physics and of Fault Mechanics are a theoretical prerequisite for the correct approach to statistical analyses of spatiotemporal behavior of seismicity and numerical modeling of Tsunamis. The natural collector of these studies is the assessment of seismic hazard for issuing construction regulations (DIFA researchers are directly involved to this aim) and the assessment of seismic risk, aimed at establishing prevention and rescue measures in seismic zones as well as the development of early warning techniques for Tsunamis. Within this framework, crustal deformation measurements by satellite techniques, measurements of the seismic response of soils and seismic imaging are also useful. The former one represents an independent observable closely connected with seismic energy release; the latter ones complement seismic hazard assessments by detailing the behavior of neighboring areas characterized by different hazard. Satellite deformation measurements are essential for monitoring the state and the dynamics of the Earth system, also in relation to sea level rise, which is source of social and economic concerns for a wide part of the World’s population living in coastal areas or close to them.

The volcanic hazard and risk assessments are the natural collectors of the Physics of Volcanism. In Italy, in fact, there are at least four areas (Mt. Vesuvius, Campi Flegrei, Mt. Etna and Aeolian Islands) where the future activity of certainly active volcanoes could produce hard consequences on the densely urbanized territory of nearby cities (Naples and Catania).

Oceanographic research is aimed at understanding the basic processes that underlie the climate variability of the currents in the Mediterranean Sea, the oceanographic short-term forecasts and the coupling between physics and marine biochemistry in order to understand the dynamics of the food chain and, more in general, the marine ecosystem.

The Physics of the Earth group has strong scientific collaborations with the Bologna sections of Centro Euromediterraneo per i cambiamenti climatici (CMCC) and Istituto Nazionale di Geofisica e Vulcanologia (INGV).

 

Earthquake source physics: Near source earthquake effects

M. Bonafede (Full Prof.), M. E. Belardinelli (Assoc. Prof.), M. Nespoli (Post Doc), F. Pintori (PhD student).

Fault motions are commonly assumed as the cause of an earthquake (earthquake source). Properly detecting and interpreting effects occurring during the so-called fault cycle is the goal of the present research. The study is carried out in collaboration with INGV, Bologna section and a Postdoc researcher at the Caltech University. Earthquakes deform permanently and transiently the rocks surrounding the earthquake source. These effects can be recorded at the Earth surface by space geodetic measurements. Part of the research activity is devoted to the acquisition of GPS data in several stations locate in Emilia Romagna and Tuscany (in collaboration with DISTART). At the same time, geodetic data contain also signatures of processes of different origin, which should be recognized before proceeding to further analysis of them. To this aim it is important to integrate geodetic data with other kinds of observations (e.g. seismicity patterns, water table level variations, soil compaction measurements) both before (interseismic stage of the fault cycle) and after (postseismic stage) an earthquake occurrence. Most of the interpretation of earthquake effects is based on the evaluation through models of the deformation induced by the same earthquake, which in turns depends on the earthquake source parameterization and medium properties. For this reason a reasonable modeling of earthquake surface effects provides support to the assumed parameterization of the earthquake source and medium parameters, which cannot be observed directly.

Funding: UniBo, Regione Emilia Romagna, INGV

 

Earthquake Physics, the thermodynamic approach

F. Mulargia (Full Prof.)

In collaboration with UC Berkeley and Tokyo University, the seismic source is studied through non-equilibrium thermodynamics and nonlinear mechanics, disposing of the paradigm of Elastic Rebound. The latter, which is based on linear elasticity and considers only the mechanical terms, is notoriously capable of effective representations of the wavefield, but is ineffective in describing the evolution of the process, which is reduced to a fracture + stick slip on elementary geometry. This leads not only to the impotence of forecasting future events, but also to several paradoxes, the first of which relates to the amount of heat produced by the earthquake sliding. The new approach addresses the problem of seismic source ab initio, by combining the thermodynamic and mechanical problems, and taking into account the presence of fluids and of a non-Euclidean geometry. This resolves the paradoxes, reconciling theory with experiment, with earthquakes occurring in clusters which are self-similar in both space and time. The new approach is also effective in describing the seismicity induced by fluid injection, reconciling the theory with experimental evidence, that sees earthquakes induced even at considerable distances and time delays from the injection, with the fluid diffusing in the solid matrix as pressure waves. A similar effect is true for the occurrence of aftershocks at spatial and temporal distances which are several orders of magnitude larger than expected from the classical approach.

Funding: RFO Università di Bologna, INGV.

 

Fault Mechanics (Theoretical Seismology)

M. Dragoni (Full Prof.), A. Piombo (Assist. Prof.), E. Lorenzano (PhD Student)

Research in fault mechanics is aimed to understanding the processes controlling the instability conditions of faults, the characteristics of fault slip and the kind of the emitted seismic waves. Faults are represented by asperity models that have proved to be a suitable tool to reproduce the main aspects of seismic sources. Stress accumulation on asperities, asperity slip and stress transfers between asperities play a central role in the seismogenic process. Models allow to simulate the evolution of a fault during the interseismic intervals and the characteristics of seismic slip. The evolution of seismicity in active fault systems is determined by taking into account the interaction between faults, the aseismic slip and the rheological properties of the Earth’s lithosphere.

Funding: RFO Università di Bologna; Contratto Progetto OTRIONS (Università di Bari)

 

Statistical seismology and seismic hazard

P. Gasperini (Full Prof.), F. Mulargia (Full Prof.), A. Petruccelli (PhD Student)

These activities are carried out in close collaboration with the INGV as part of its agreements with the Italian Department of Civil Protection (DPC). They concern both the improvement and standardization of databases of seismicity both at the Italian and Mediterranean scale through the development of innovative methods and procedures that have had a good following in the scientific literature. In particular there have been developed an algorithm (BOXER) for the location of historical earthquakes based on the descriptions of macroseismic effects, a procedure for verification and cataloguing of more than 10,000 earthquake focal mechanisms of the Euro-Mediterranean area (EMMA) and a methodology for the homogenization of the various definitions of earthquake magnitude. The seismic sequences occurred in Italy and in other regions have been analyzed so that to characterize their behavior for predictive purposes. Homogeneous earthquake catalogues for Italy, the Mediterranean and the entire globe were produced, including the reference catalogue for seismic hazard assessment in Italy CPT11. The activities in this field will bring in the next one or two years to a new version of the catalogue that will be used for future Italian hazard assessments for regulatory purposes. In this context it is also relevant the statistical study of the predictive effectiveness of possible precursory phenomena of earthquakes within the Seismological S3 project funded under the Framework Convention INGV-DPC 2012-2021 which showed statistically that there are no geodetic and geochemical precursors to the 2012 earthquakes in Emilia, Po Valley and Garfagnana.

The combined use of non-equilibrium thermodynamics and nonlinear mechanics in our modeling of the seismic source leads to a substantial improvement in the ability of forecasting earthquakes, allowing in turn estimates of seismic risk more reliable and accurate than the traditional time-independent approach.

Funding: RFO Università di Bologna; Seismological Project S3 within the ambit of the DPC-INGV agreement 2012-2021.

 

Surface waves and urban seismic microzonation

S. Castellaro (Assist. Prof.), F. Mulargia (Full Prof.)

We study simplified methods to measure the subsoil stiffness, which is a relevant property to seismic engineering, down to large depth (> 100 m) and under dynamic conditions. We apply such methods to the seismic microzonation of some municipalities in Italy (agreement with local municipalities) and Cameroun (Kribi).

Within the European project “Study of Multi-building Interactions and Site-City Effect through an idealized experimental model” we conduct experiments on the large scale shaking table laboratory at the Bristol University (UK) to validate the theoretical models of soil-structure interaction during earthquakes.

We study geophysical methods to assess the efficacy of the geotechnical methods to improve the subsoils, both in the case of existing foundations (agreement with Uretek s.r.l.) and structures/foundations still to be constructed (University of Western Sydney – Australia, Ecole Nationale des Travaux Publics de L’Etat di Lyon, France).

We study the performance of passive 1D, 2D and 3D multichannel surface-wave based techniques as a function of the source distribution. In particular, the original techniques of passive seismic developed by us have proved capable, with recordings of a few minutes using tremor sensors, to image the subsoil down to depths of the order of kilometers.

Funding: DPC-INGV projects; European FP6 NISMIST, FP7; agreements with private (Uretek srl, ENSER srl)  and public offices (municipality of Forlì and Cesena)

 

Passive seismic imaging

S. Castellaro (Assist. Pro.), F. Mulargia (Full Prof.)

Seismic microtremor is considered as nuisance from traditional seismology, which pays attention mainly to waveforms produced by earthquakes.

Recent advances in theoretical Physics and signal analysis has shown that the spatial correlation of microtremor is actually rich in information about the path crossed by the waves (i.e. about the local subsoil conditions), with the advantage that microtremor is available anywhere and at any time.

We study solutions to retrieve the Green function from the spatial correlation of seismic waves also in case of non diffuse wavefield, which is the rule in practice. This allows to develop single station and multichannel passive seismic imaging techniques and to identify the noise sources. These studies focus upon the use of the Earth as a detector of gravitational waves by measuring elastic excitement that they induce, and in particular on the calculation of the coupling constants and of the gravitational-elastic cross section.

Funding: DPC-INGV projects; European FP6 NISMIST, FP7.

 

Crustal deformation studies using space geodetic and terrestrial techniques and methods

S. Zerbini (Full Prof.), S. Bruni (Post Doc), M. Errico (Post Doc.), F. Petracca (Post Doc.), E. Santi (Post Doc.)

The research activities deal with crustal deformation studies over different spatial scales, from the local scale to the regional and global ones, by using mainly, however not limited to, space geodetic techniques. Starting in mid 1996, a network of five permanent GPS/GNSS stations has been installed in Northeastern Italy; they are located at Bologna, Medicina, Loiano, Marina di Ravenna and Trieste. Two of these sites, namely Bologna (BOLG) and Medicina (MSEL), belong to the European permanent GNSS network EPN (EUREF Permanent Network) and provide daily the acquired data to the EPN Central Bureau (Brussels). The site locations are such to contribute to different scientific objectives. For example, studies of tectonic nature made possible through the analysis and interpretation of data allowing high accuracy estimates of both the vertical and horizontal motions of the Earth’s crust. Subsidence affects the Po Plain and northeastern Italy; therefore, monitoring and studying this phenomenon is not only scientifically relevant but it has also major social-economic implications. The high-accuracy determination of crustal movements has most important applications when monitoring deformation in areas subjected to hydrocarbons upstream/production, reinjection and storage. Contributions to sea-level change/variations studies are provided by the Trieste and Marina di Ravenna stations co-located with the tide gauges; in fact, the GPS data allow estimating with high accuracy and continuity the vertical land movements that shall be removed from the tide gauge measurements. At Medicina, since 1996, a superconducting gravimeter (SG) is operative in the framework of a collaboration with the Bundesamt fuer Kartographie und Geodaesie (BKG, Frankfurt, Germany). This instrument, co-located with the GPS (MSEL) and part of the international network of SGs (Global geodynamics project, recently become an IAG Service), measures the temporal variations of the gravity field continuously and it is periodically controlled by means of absolute gravity measurements. Continuous monitoring of height and gravity changes allows the separation of the gravity potential signal due to mass redistribution from the geometric signal due to height changes and the sound interpretation of crustal deformation processes. Another area of research concerns the comparison and combination of GPS data with those provided by the SAR technique (Synthetic Aperture Radar). This research, developed in collaboration with DEIB of the Milan Polytechnic, has a twofold objective; on the one hand to obtain a space and time continuous description of the deformation by taking advantage of the techniques’ complementary aspects, on the other to develop a comparison of the tropospheric delays estimated with the two different techniques. In The group is also actively contributing to the research in the field of reference frame computations, in collaboration with the colleagues of the French National Geographic Institute (IGN), responsible for realizing and maintaining the official International Terrestrial Reference Frame (ITRF) adopted by the International Earth Rotation and Reference System Service (IERS). In particular, the study aims at evaluating whether the space ties on-board GNSS satellites can replace terrestrial ties in the realization of the ITRF. The research encompasses the analysis of both real data and numerical simulations and is of significant importance in the framework of the GRASP (Geodetic Reference Antenna in Space) satellite mission, currently under evaluation both at NASA (National Aeronautics and Space Administration) and ESA (European Space Agency).

Future activities will be based, however not limited to, on further developments of the researches previously described.

Funding: ENI SpA, RFO

 

Numerical modeling of Tsunamis and early warning systems

S. Tinti (Full Prof.), A. Armigliato (Assist. Prof.), F. Zaniboni (Assist. Prof.), G. Pagnoni (Post Doc.)

Research activities in this field regard primarily modeling of tsunamis generation by dislocation events, slope failures and volcanic eruptions as well as the study of tsunami propagation and impact on the coasts and on coastal structures and infrastructures. Applications are the assessing of tsunami hazard, vulnerability and risk in the Mediterranean with special attention to Italy and the setting up of monitoring network and tsunami alert systems. Most of these activities have been and are being undertaken in the frame of European RD projects like TRIDEC (Collaborative, Complex and Critical Decision-Support in Evolving Crises) and NearToWarn (Near-Field Tsunami Early Warning and Emergency Planning) just ended and ASTARTE (Assessment, STrategy And Risk Reduction for Tsunamis in Europe) still ongoing.

Funding: RFO (University of Bologna), national projects (RITMARE), European Projects (TRIDEC, NEARTOWARN, ASTARTE)

 

Dynamic modeling of landslides

S. Tinti (Full Prof.), F. Zaniboni (Assist. Prof.), M. A. Paparo (Post Doc.) K. Elsen (PhD Student)

The study of landslides concerns stability conditions of subaerial and submarine slopes accounting for morphological, geological, geotechnical and geophysical properties of soils with development of numerical models aiming at determining the incipient failure and involved volumes. The study covers also the simulation of landslide evolution to compute trajectories, acceleration and velocity of the sliding body, to estimate the zone where it stops and deposit forms, and the impact on the environment. Furthermore, when slope failures occur close to water basins or underwater, models compute the impact on the water body (see the case of the 1963 Vajont landslide) and the generation of tsunamis (see the 2002 Stromboli tsunami).

Funding: RFO (University of Bologna), European Projects (TRIDEC, NEARTOWARN, ASTARTE)

 

Physics of volcanism, Dynamics of volcanic intrusions

M. Bonafede (Full Prof.), M.E. Belardinelli (Assoc. Prof.), C. Ferrari (Post Doc.)

Studies in Physics of Volcanism are mainly oriented to understand the dynamics of magma ascent, based on different observables such as ground deformation, gravity changes and seismic activity, that provide information on the depth of the intrusion, the stress field and the volumes of magma involved through inversion techniques. These studies have important implications for asserting the risk of volcanic eruptions. The studies of this research group, carried out in collaboration with researchers from INGV, are primarily focused on the area of Campi Flegrei. This area was repeatedly affected by several phenomena of unrest in historic time: in particular the area is presently experiencing a new phase of acceleration of deformation processes, accompanied by seismicity and by changes in physical and chemical parameters of gas emitted from the soil. The data of radar interferometry (from COSMO-Skymed satellites) made it possible to detect the vertical and horizontal components of the strain field on a dense grid of points on the ground, and show uplift rate ~ 10 cm / year in the center of the caldera. A very accurate inversion model, taking into account the three-dimensional structure of the region, shows that an inclined dyke at about 5 km depth is responsible for the deformation pattern. This source is almost coinciding with the source of bradyseism observed in the 80s. The presence of a major component of "shear" indicates that the source is extending to affect previously unfractured rocks with obvious implications for the increased hazard of a possible forthcoming eruption.

Funding: UniBo, INGV

 

Thermo-fluid-dynamics of lava flows (Physics of Volcanism)

M. Dragoni (Full Prof.), A. Piombo (Assist. Prof.), E. Lorenzano (PhD Student)

Lava flows are a physical system in which the thermal, rheological and dynamical aspects are strongly coupled. The research employs both analytical and numerical models with the aim to highlight the relationships existing between the many quantities describing the system and to predict the evolution of a lava flow as a function of the effusion rate of lava at the eruption vent, of its rheological properties, of the ground morphology and of all the other variables controlling the flow. In particular, the research is aimed to understand the conditions and the mechanisms of formation of lava tubes, that have a strong impact on the cooling rate of the flow. The processes controlling the variation in time of the effusion rate of lava are also studied.

Funding: RFO Università di Bologna; Contratto Progetto OTRIONS (Università di Bari)

 

Oceanography

N. Pinardi (Assoc. Prof.), M. Zavatarelli (Assoc. Prof.), L. Giacomelli (technician), F. Trotta (Post Doc.), E. Fenu (Post Doc.), E. Fiori (Post Doc.), G. Mattia (Post Doc.), G. Mussap (PhD Student), A. Sepp-Neves (PhD Student), G. Verri (PhD Student)

Oceanographic research activities are focusing on ocean interdisciplinary numerical modelling aimed at understanding the dynamics and the spatio-temporal variability of ocean physical processes, as well as the marine ecosystem dynamics and its coupling with ocean physics.

The main research themes are the following:

  • Time series analysis of interdisciplinary oceanographic data for the coastal and the offshore areas, to describe and understand the ocean climate variability in the Mediterranean and the global ocean;
  • Time series analysis of atmospheric data, with particular reference to the air-sea interactions (heat and momentum exchange).
  • Development of numerical models to simulate the Mediterranean and Adriatic Sea circulation.
  • Development of relocatable numerical models to study mesoscale and submesoscale processes.
  • Numerical modeling of the marine ecosystem and implementation in the Adriatic and the Mediterranean Sea;
  • Development of numerical models simulating transport and fate of marine pollutants.

The group is active at DIFA and at the SINCEM laboratory located in the Ravenna Campus. There are close interactions with the Bologna INGV group, in the field of operational oceanography of the Mediterranean Sea and also with the Bologna and Lecce sections of the Centro Euromediterraneo per i cambiamenti climatici (CMCC). The members of the group are active in several EU research projects aimed to develop the COPERNICUS Mediterrranean Sea marine Service (www.copernicus-marine.eu).

Group members are also coordinating research units in the EU FP7 Projects EMODNET-MEDSEA (European Marine Observation and Data Network - Mediterranean Sea),  PERSEUS  (Policy Oriented Environmental Research in the Southern European Seas), the MIUR-PON project TESSA (Technologies for the Situational Sea Awareness) and the H2020 project AtlantOS (Optimizing and Enhancing the Integrated Atlantic Ocean Observing System). They coordinate the development of the Biogeochemical Flux Model (BFM, http://bfm-community.eu/) and contribute to the development of a numerical oil fate and transport model. (http://medslikii.bo.ingv.it/).

Contacts

Alberto Armigliato

Associate Professor

Dipartimento di Fisica e Astronomia

Viale Berti Pichat 8

Bologna (BO)

tel: +39 051 20 9 5003

tel: +39 051 20 9 5059

fax: +39 051 20 9 5058

Maria Elina Belardinelli

Associate Professor

Dipartimento di Fisica e Astronomia

Viale Berti Pichat 8

Bologna (BO)

tel: +39 051 20 9 5018

Maurizio Bonafede

Adjunct Professor

Presidenza della Scuola di Scienze

Via Selmi 3

Bologna (BO)

tel: +39 051 20 9 5017

Silvia Castellaro

Associate Professor

Dipartimento di Fisica e Astronomia - DIFA

Viale Berti Pichat 6/2

Bologna (BO)

tel: +39 051 20 9 5002

Michele Dragoni

Professor

Dipartimento di Fisica e Astronomia

Viale Berti Pichat 8

Bologna (BO)

tel: +39 051 20 9 5020

fax: +39 051 20 9 5058

Paolo Gasperini

Professor

Dipartimento di Fisica e Astronomia - DIFA

Viale Berti Pichat 6/2

Bologna (BO)

tel: +39 051 20 9 5024

Francesco Mulargia

Professor

Dipartimento di Fisica e Astronomia - DIFA

Viale Berti Pichat 6/2

Bologna (BO)

tel: +39 051 20 9 5022

Nadia Pinardi

Associate Professor

Dipartimento di Fisica e Astronomia

Viale Berti Pichat 8

Bologna (BO)

tel: +39 051 20 9 5023

tel: +39 0544 937324

fax: +39 0544 937333

Antonello Piombo

Assistant professor

Dipartimento di Fisica e Astronomia - DIFA

Viale Berti Pichat 6/2

Bologna (BO)

tel: +39 051 20 9 5013

fax: +39 051 20 9 5058

Stefano Tinti

Professor

Dipartimento di Fisica e Astronomia - DIFA

Viale Berti Pichat 6/2

Bologna (BO)

tel: +39 051 20 9 5025

tel: +39 051 20 9 5164

Filippo Zaniboni

Junior assistant professor (fixed-term)

Dipartimento di Fisica e Astronomia

Viale Berti Pichat 8

Bologna (BO)

tel: +39 051 20 9 5061

fax: +39 051 20 9 5058

Marco Zavatarelli

Associate Professor

Dipartimento di Fisica e Astronomia - DIFA

Viale Berti Pichat 6/2

Bologna (BO)

tel: +39 051 20 9 5060

Susanna Zerbini

Professor

Dipartimento di Fisica e Astronomia

Viale Berti Pichat 8

Bologna (BO)

tel: +39 051 20 9 5019