Transcript Coupling geophysical modelling and geodesy to

Università
di Milano
Coupling geophysical modelling and
geodesy to unravel the physics of
active faults
SISMA
Seismic Information System for
Monitoring and Alert
Galileian Plus
Dipartimento di Scienze della Terra, Università di Milano, Italy
Politecnico di Milano, Italy
Dipartimento di Scienze della Terra, Università di Trieste, Italy
Agenzia Spaziale Italiana, Sezione Osservazione della Terra
SISMA: a new approach towards the understanding of
earthquake generation and seismic hazard
mitigation. It builds over three major concepts:
-
taking advantage of the new generation of DINSAR and GPS deformation data at the
Earth’s surface, in conjunction with seismic flow monitoring
which in turn allow us
-
building an integrated geophysical, geodetic and seismological scheme to disclose
stress build up within the gouge of seismic active faults for a deterministic approach
of earthquake cycle description
which in turn allows us
-
overcoming the obvious shortcomings of the old approach to seismic hazard
mitigation based on a purely probabilistic approach
3° level
2° level
1° level
SISMA Overall Schema
Acquisition of the historical
SAR images of the area.
Establishment of a local
network of GPS Receivers
For geodynamic purpose
Near Real Time GPS
processing to retrieve
continuously updated
deformation and
velocity maps
Seismicity Analysis
Restrained areas
for GPS and SAR
Near Real Time SAR
Data processing to
retrieve continuously
updated deformation
NRT Geophysical
Forward modeling
Permanent
GPS
Evaluation of seismic hazard
• Maps of alerted areas, prone to earthquake
events with given magnitude, will be obtained
through comparison of non-EO information,
provided by seismological data analysis, and
taking into account results provided by
Geophysical Modeling based on EO information;
• EO observations, consisting of GPS and DinSAR
images, will permit to draw deformation maps on
the surface;
• Stress maps at the depth of the active faults will
be obtained through integration of EO geodetic
information into Geophysical Forward Modeling.
EO Data in Near-Real-Time Applications
GPS
DinSAR
Geophysical
Modeling
NRT application
in alerted areas
Strain-rate and stress maps
at local and national scale
•
Which is the contribution of Earth Observations?

Inter- and pre-seismic phases: monitoring of
surface deformation, which is a possible
indicator of stress build up on faults

Co-seismic phase: improves the understanding
of the process taking place along the fault plane
and permits the estimation of the interactions
between the stress field (modified after the
seismic event) and the nearby faults.

Post-seismic phase: monitoring possible
phenomena (e.g. after-slip, post-seismic
relaxation) that may affect the stress field in the
lithosphere
Three seismogenic zones,
Friuli-Venezia Giulia
Umbria-Marche
Pollino (Calabria)
are test sites for SISMA
These active seismogenic zones are embedded
within the diffuse plate boundary between Africa and
Eurasia, in the central Mediterranean
Africa-Eurasia
relative motion from
paleomagnetic data
(NUVEL-1A)
Seismicity (Ms, NEIC 1903-1999)
and calculated seismic strain rate
Comparison between predicted crust and lithosphere deformation patterns and GPS
data to verify the feasibility of seismic hazard mitigation: baseline variations
GPS DATA
Marotta, A. M. et al., JGR 2004 – Combined effects of tectonics and glacial isostatic adjustment on
intraplate deformation in central and northern Europe: Application to Geodetic baseline
analysis.
Horizontal principal strain rate tensor
Model B:
active convergence
+
subduction forces in the Hellenic (deep slab) and
Calabrian arcs
Jimenez-Munt, I. et al., (2003) Active deformation in the
Mediterranean from Gibraltar to Anatolia inferred from numerical
modeling and Geodetic and seismological data
CN
algorithm
Northern Region, Mo=5.4
6.5
1965
1975
5.4
1985
5.8
6.0
5.8 6.0 5.55.65.5
1995
2005
1955
Central Region, Mo=5.6
1965
6.5
1975
1985
5.7
6.0 5.7
1995
5.8
5.8 6.0
2005
1955
Times of Increased
Probability for the
occurrence of events
with M>Mo within the
monitored regions
Southern Region, Mo=5.6
6.5
1965
1975
5.7
1985
1995
2005
M8S
algorithm
Monitored region
Alerted region
Events with Mmax 5.5
occurred since July 2003
2003.5-2004
M6.5
(Peresan al., Earth Sci. Rev. 2005)
2004-2004.5
M6.0
2004.5-2005
M5.5
2006.5-2007
Updated to March 1 2007
Methodology for detecting the movements during the
co-seismic phases in earthquake prone areas
(Crippa B. et al., 2006).
(a)
(b)
Surface deformation obtained by
geophysical inverse modeling (a)
and DInSAR analysis (b).
(c) misfit between prediction and
observation
(c)
m
Our preliminary results confirm the benefits coming
from the usage of Earth Observation data to
improve the capability of monitoring active
faults in Near Real Time: an important
step toward the mitigation of seismic hazard