Assessing global earthquake risks: the Global Earthquake Model (GEM) initiative - Seismic Risk Analysis and Management of Civil Infrastructure Systems - page 818

related archive represent an important step in the creation of a global
homogenised earthquake history and already proves to be an extremely
important information source for PSHA. This two-year project is being
coordinated by two leading institutions: INGV (Italy) and BGS (UK).

30.2.2 Global Instrumental Catalogue

The International Seismological Centre (based in the UK) in collaboration
with a team of international experts is leading this initiative aimed at the
creation of a homogeneous instrumental seismicity catalogue for the period
1900-2009 (http://www.globalquakemodel.org/hazard-global-components/
instrumental-catalogue).
This global catalogue of earthquakes will contain about 25.000 events. In
the interval 1900-1917 the catalogue will comprise events with magnitude
greater or equal to 7.5; from 1918 until 1959 it will have events with mag-
nitude greater of equal to 6.25 and, fi nally, from 1960 on the catalogue will
include earthquakes with magnitude equal or greater than 5.5.
This catalogue will be composed of earthquakes with homogeneous loca-
tions and magnitude estimates, determined using the same tools and tech-
niques to the extent possible. The magnitude determination and location
procedures applied represent a synthesis of state-of-the art methods. Each
event will have a M W value (with related uncertainty) based on seismic
moment where possible (mainly for the events occurred in the window
1976-2009); in the other cases, empirical relations between M W and M S / m b
will be used to obtain proxy values of moment magnitude.
Most of the events in the pre-1971 period will have their M S magnitudes
computed in a systematic manner from the surface wave amplitude mea-
surements recovered from the historical paper-based seismic station bul-
letins. These M S magnitude were never available before; they are the
results of a massive data entry effort completed under this project. Some
IASPEI observers also provide feedback to the activities of this global
component.

30.2.3 Global Active Fault and Seismic Source Database

The GEM Faulted Earth project, coordinated by GNS Science (New
Zealand) and Earth Observatory Singapore is creating a database of
active faults and faults sources following a common set of strategies,
standards and formats (http://www.globalquakemodel.org/hazard-global-
components/active-faults). This consortium has already created an archive
of existing national or international databases to better comprehend the
state-of-the-art and produced a database schema able to gather the infor-
mation currently available in different formats. The fi nal GEM Faulted