Information Technology Reference
In-Depth Information
17.3.1 The VERCE Use-Cases
The VERCE
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computational platform aims to provide the facilities to ful
ll the
requirements of
ned seismological applications: cross-correlation
analysis and forward modeling/inversion. A short description of these is provided
below.
Cross-correlation analysis
: This technique, also called passive imaging, allows
the detection of relative seismic-wave velocity variations that are associated with
the stress-
two well-de
eld changes that occurred in the test area during the time of recording. It
uses the cross-correlation of noise signatures originating at depth and recorded at
surface receivers to retrieve the Green
s function between these receivers, thereby
reconstructing the impulse response of the intervening plate (Bensen 2007).
Forward modeling/inversion
: Forward modeling generates synthetic seismo-
grams for various Earth models. This is achieved by the execution of high per-
formance computing (HPC) simulation codes, which are called solvers. The
synthetic data produced by the solvers may be compared with real observations for
earthquakes on a continental scale, in order to foster subsequent model updates and
improvement (inversion) (Fichtner 2008; Moczo 2006).
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17.3.2 WS-PGRADE Integration Strategy
The integration of the VERCE platform within the SCI-BUS scienti
c gateway
framework has been conducted according to the following plan:
Deployment tests
: A number of deployment tests had to be performed to verify
that the system was flexible enough to run on the VERCE resources. The tests were
successful and so far there are two installations available, for test and production
respectively.
Investigation of security issues
: The authentication and authorization model
adopted by VERCE is based on X.509 VOMS-enabled certi
cates, which reflects the
EGI regulations. Indeed, the support for a flexible certi
cate management system
offered by WS-PGRADE was a crucial feature, which immediately con
rmed the
value of adopting that framework. Moreover, the possibility of producing and
uploading users
cates interactively is offered through the VERCE sci-
ence gateway. Two applets, MyProxy Tool and a Grid Security Infrastructure -Secure
Shell (GSISSH)-Term,
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maintained at LRZ,
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can be used to create and upload both a
regular and a Virtual Organization Membership Service (VOMS)-enabled proxy and
to access the clusters of the VERCE platform via an interactive GSISSH terminal.
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proxy certi
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