Activity 8.3 – Seismology
Coordinators: P. Gasparini and A. Zollo
Collaborators: J. Battaglia, A. Bobbio (OV-INGV), L. Cantore, P. Capuano (UniMol), V. Convertito,
M. Corciulo, D. Dello Iacono, R. De Matteis (UniSannio), A. Emolo, G. Festa, G. Iannaccone (OVINGV), M. Lancieri, C. Martino, S. Nielsen (OV-INGV), L. Romano (OV-INGV), A. Romeo, C.
Satriano, M. Grazia Spatola (OV-INGV), T. Stabile, M. Vallée (OV-INGV), M. Vassallo, E. Weber
(OV-INGV)
Probabilistic approach to the seismic hazard assessment. A theoretical approach
aimed at introducing a priori information about kinematical source parameters in the
classical attenuation laws has been developed. The analysis is devoted to refine
ground motion estimates when complete and homogeneous data-bases are not
available and, in particular, it is focused on the focal mechanism. A new method
aimed at integrating the classical probabilistic approach with deterministic approach
for a characteristic earthquake scenario has been developed.
EduSeis: a didactic seismograph. In the EduSeis frame, an e-learning platform has
been experimented at high school ITIS “MAJORANA”. This model is based on the
Computer Supported Collaborative Learning (CSCL) that is an innovation method
for teaching and learning and that adopts the modern information and communication
technologies. The EduSeis educational activities (earthquake location, magnitude
estimate, seismogram analysis,…), that are mostly based on web and net
communication tools, are suitable for this kind of experimentation and their didactic
value is one of the main educational objectives of this project.
Seismic exploration. Innovative processing techniques to built seismic sections from
intermediate to wide angle data based on CMP gathers have been developed.
Velocity analysis techniques based on the semblance function have been
implemented, tested and applied in the case of post-stack migration of reflection data
sets acquired in Southern Apennine zones by Enterprise Oil Company (ESIT 700
data). Tomographic inversion has been performed in order to retrieve velocity crustal
structures using standard methods. This technique is based on the optimization of the
semblance function and requires a starting velocity model.
Seismic source and strong ground motion simulation. Two inversion techniques of
high frequency seismograms for retrieving the kinematic seismic source parameters
have been implemented and tested. The former is based on the non linear
optimization of a misfit function by the genetic algorithm. The latter is based on the
back-propagation of ground motion amplitudes on the fault plane. A method for
simulating the seismic radiation associated with the rupture of an extended fault in
high-frequency approximation has been implemented and applied both in the case of
real earthquakes (e.g., 1930 Irpinia earthquake; 1997 Colfiorito earthquake) and in
the case of hypothetical earthquakes occurring on given seismogenetic structures
(e.g., Val d’Agri, Città di Castello) for estimating the ground motion parameters of
engineering interest.
Seismic tomography of Neapolitan volcanoes. The work began in 2003 in the
Neapolitan volcanic areas and it has continued during 2004, in particular for the
Campi Flegrei area. Data set acquired during the Serapis survey (2001) and data set
collected during the last bradiseismic crisis (1982-84) have been used to obtain a
reliable 3D tomographic model for the bays of Naples and Pozzuoli. The retrieved
high velocity and high density body in the Pozzuoli bay, has been interpreted as the
buried rim of the Campi Flegrei caldera at about 1 km deep. A limestone body
retrieved at about 4 km deep has been interpreted as the top of the limestone
basement underneath the caldera. Moreover a low Vp/Vs ratio at about 4 km deep
suggests the absence of magmatic fluid at that depth.
Seismic early warning. We are developing a prototype system for seismic early
warning in the Campania region. Our purpose is to provide a 10 to 20 seconds
seismic pre-alert and a rapid (1 to 5 minutes) post-event scenario to the city of
Naples and to specific targets in the Campania region (bridges, railways, plants, …).
The system will trigger automatic pre-event actions and will provide a reference
scenario for the immediate post-event emergency procedures. It is designed as a
geographically distributed seismic network with several levels of real time data
analysis, exchange and storage.
Development, implementation and verification of a system for transmission and
management of seismic data acquired in submarine environment. We have performed
some simulations of underwater acoustical signal propagation in order to better
understand the effects of the submarine environment, and to assess and predict how
these environmental effects could impact the performance of an acoustic
transmission systems. For the simulations we use the sound velocity profilers
(acoustical velocity vs. depth) measured, in different months, in the Naples gulf. We
have analyzed the variability (in the space and in the time) of sound velocity and
some simulation results performed for different months of the year. Using these
numerical simulations we have constructed the transmission losses maps that allow
us to estimate the performance of the acoustic transmission system.
Program for 2005
Probabilistic approach to the seismic hazard assessment. The new integrated method
will be applied in the case of the November 23, 1980 Irpinia, Southern Italy,
earthquake (M 6.9). An automatic procedure for the inversion of P-wave spectra for a
large waveforms data-set in order to retrieve scaling laws on seismic source
parameters will be implemented and applied to the 1988-2003 data-base by the
Istituto Nazionale di Geofisica e Vulcanologia (INGV). A procedure for “near-real
time” regression analysis on peak ground motion parameters for the sake shaking
maps will be implemented.
EduSeis: a didactic seismograph. During 2005 we will develop and implement new
teaching methodologies in Earth Sciences, using seismology as a vehicle for
scientific learning in collaboration with some high schools, the “Osservatorio
Vesuviano” and the Scientific Museum “Città della Scienza”.
Seismic exploration. In 2005 work will focus on detection and model of interfaces
which are registered as reflected/converted phases on seismic sections.
Seismic source and strong ground motion simulation. The inversion techniques for
source kinematic parameters determination will be applied in cases of earthquakes of
both Italian and not areas. A technique for simulating the full wave-field produced by
a rupturing fault will be implemented and tested.
Seismic tomography of Neapolitan volcanoes. In 2005 the work will focus on
understanding the position of the magmatic reservoir beneath the caldera and his
relationship with Mt. Vesuvius reservoir. This aim will be persuaded analysing
converted/reflected phases.
Seismic early warning. We will develop and test automatic procedures for real time
event detection, location and magnitude estimate and for the construction of a rapid
post-event scenario. We will test the efficiency of the entire process of data
acquisition, transmission and analysis and of the information broadcasting system.
Development, implementation and verification of a system for transmission and
management of seismic data acquired in submarine environment. We have recorded
one month of broadband seismic data acquired on the sea-bottom of Pozzuoli gulf in
order to evaluate the level of seismic noise. For this purpose we will perform spectral
analysis of recorded data (determination of Power Spectral Density curves) and a
comparison between sea bottom and on land earthquake registrations.