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Overview of the Geoscope Observatory

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Introduction

 
Created in 1982, GEOSCOPE Observatory is constituted by a network of 34 seismological stations spread in 18 countries and a data center located at the Institut de Physique du Globe de Paris which manages and distributes the the data.
GEOSCOPE Observatory aims to provide the broad-band seismological data of its stations to the french and international scientific community. The location of the stations has been chosen in cooperation with the FDSN (International Federation of Digital Seismograph Networks), in order to cover better emerging lands. More about the FDSN...

 

Scientific objectives

The scientific objectives of GEOSCOPE are centered on the comprehension of the terrestrial dynamics from studies of structures and seismological sources. GEOSCOPE data are used by both, the french and the international scientific community. Between 1982 and 2009 more than 1000 scientific articles have been counted which used GEOSCOPE data.

scientific committee has been created in 2007. It is constituted with a representative of the main French laboratories of Seismology, and 3 foreign seismologists. It convenes every 2 years to discuss and validate the future orientations of the GEOSCOPE Observatory. The observatory has been labelled Observatoire de Recherche en Environnement in 2006. GEOSCOPE is funded by INSU/CNRS, the Ministry of Education and Research and european contracts.

 

GEOSCOPE Network

The stations are installed in vaults, the type of place depends on the country. The stations are equiped with three broad-band seismometers type STS1 or a 3-component seismometer type STS2, a digitizer, and a local storage system for the data. In most of the stations, air-pressure and temperature sensors are installed too. The stations are gradually up-graded to send data in real time towards the GEOSCOPE data center via a satellite link or ADSL.
 
The transmission of the data in real time allows the tsunami warning centers and the earthquake detection centers to use the GEOSCOPE Network to detect main earthquakes.
 
The locations of the GEOSCOPE stations, especially those in the south hemisphere, are of prime interest to constrain well the seismic source. By the way, 2004 Sumatra earthquake and more recently October 2009 Samoa earthquake reminded the importance of real time data acquisition for tsunami warning.
 
The station management of the GEOSCOPE Network is made in cooperation with IPGP, EOST, CEA/DASE, CNES, IRD, PEV, USGS and local universities which shelter the stations. The repartition of the responsability of the stations is presently the following :
  • IPGP manages 23 stations (2 with IRD, 4 with local universities)
  • EOST manages 7 stations (1 with IRD and 5 with IPEV)
  • CEA/DASE manages 2 stations
  • IRD manages 3 stations (1 with EOST)
  • USGS manages 2 stations
  • Local universities manage 4 stations (with IPGP)

Up-grading stations means changing the digitizer, installing remote control modulus and real-time data transmission modulus. The new systems of remote control of the state of the stations allows to identify from Paris the causes of failure before they have any incidence on the seismic data and solve them in cooperation with the local correspondents. The new stations have got enough energy autonomy to ensure the continuity of data recording during power cuts which are frequent in many countries. Their autonomy allows also to manage automatically the problems of telecommunication. The stations are equipped with a system of protection against lightning.

The seismometers of type STS1 which equip most of the GEOSCOPE stations are the most efficient on the market (lowest noise level) but they are not built any more. The electronics of STS1 seismometers are less ans less efficient while the mechanic part of the seismometers remain operational. New electronics for these seismometers have been developped (METROZET) recently and are gradually installed in all the GEOSCOPE stations equipped with STS1 seismometers.


IPGP Data Center

Data from GEOSCOPE stations are collected,archived and distributed by the IPGP Data Center. The data are sent in real time or time lag from every station to Paris. After validation or possible correction, the data are archived and automatically opened to the international scientific community from the data center in Paris as well as from the other five worldwide seismological data centers associated to FDSN.