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|Authors: ||Pacor, F.*|
|Title: ||Task 5 - Potenza - Deliverable D17: Bedrock shaking scenarios|
|Issue Date: ||Jul-2007|
|Series/Report no.: ||D17|
|Keywords: ||Shaking scenario|
|Abstract: ||The main goal of this report is the computation of the bedrock seismic scenarios in the
Potenza city (Southern Italy) to be used for evaluating damage scenarios (described in
PS3-Deliverables D18-D19-D24). This area represents one of the prediction case studies,
planned in the framework of Project S3 which aim is the production of ground shaking
scenarios for high and moderate magnitude earthquakes. The area around Potenza was
affected by several destructive earthquakes in historical time (Table 2.1.1) and a number of
individual sources representing the causative faults of single seismic events with
magnitude up to 7 were identified. Deeper and smaller faults are present very close to the
Potenza city, generating events with M up to 5.7 (1990 Potenza earthquake).
Due to the involved source-to-site distances (about 25 km) and to the computation
resolution of the simulation techniques, the site is represented by a single point. In total 9
faults were identified and the deterministic shaking scenarios are computed for each of
The following strategy is adopted to provide ground motions.
We compute shaking scenarios at level 1, using a simplified simulation technique (DSM,
Pacor et al.; 2005) for all the faults. By these simulations we identify the three faults (F3, F7.
and F8) producing the maximum expected shaking at the Potenza city, in terms of peak
ground acceleration, peak ground velocity and Housner intensity. Based on these results,
simulations at level 2, using the broad band technique HIC (Gallovic and Brokeshova,
2007) have been performed at Potenza for F3, F7 and F8 sources.
For the Potenza city, we decided to predict the shaking scenarios at level 2, in order to
provide suitable estimates of the low frequency ground motion (e.g. velocity time series)
and engineering parameters (e.g. Arias intensity) strictly related to the duration of the
signals. For each source, we generated hundreds of rupture models varying slip
distribution, nucleation points and rupture velocity, and for each model we simulated the
acceleration time series by HIC. Then we computed the probability density functions
(PDF) of the ground motion parameters (PGA, PGV, PGD, Arias and Housner intensities)
and estimated several statistical quantities in order to select families of accelerograms to be
used for damage analysis: mean and associated standard deviation, median, 75%
percentile, 84% percentile, mode, minimum and maximum.
Finally we provided to the engineering Research Unit 6 of this project three sets of 7
accelerograms, having ground motion parameters equal to the statistical requirements
computed by the synthetic distributions.
The first set includes 7 accelerograms (three components), each of them having PGA equal
to the mean, median, mode, 75-percentile, 84-percentile, minimum and maximum values
of the PGA distribution. The second set and third sets include 7 accelerograms (horizontal
components only), having PGA and Housener Intensity in the neighborhood of the
median values of the corresponding distributions. A further comparison of adopted
procedure for the predicted ground motion at Potenza was performed with respect to
stochastic ground motions generated with EXSIM method (Motazedian and Atkinson;
2005). Even if the scenarios modelling was carried out varying different kinematic
parameters, the statistical parameter were quite similar.
Finally to provide shaking scenarios in term of macroseismic intensity, we applied a
probabilistic empirical approach, developed in Progetto DPC-INGV S1.|
|Appears in Collections:||04.06.04. Ground motion|
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