The French MOBAL'03 Experiment
The MOBAL'03 Transect
MoBaL is the acronym for "Mongolian-Baikal Lithosphere seismological Transect". This work was led in the framework of the French CNRS Research Program called PICS ("Programme International de Coopération Scientifique") entitled "Déformations actives et structures lithosphériques en domaine intra continental : étude intégrée du système Mongolie-Baïkal". It implies a collaboration between CNRS in France, Academy of Sciences in Russia (Siberian Branch of the RAS) and Academy of Sciences in Mongolia.
1 (2001) was dedicated to paleoseismology under the direction
by Jeff RITZ.
The 2003 MOBAL Experiment aimed at imaging the crustal and upper mantle structure from the Siberian platform in the north to the Gobi-Altay range in the south, in order to provide geodynamic constraints to deep lithosphere and asthenosphere velocities and deformations, and their relations to the Siberian craton, the Baikal rift, the Hangay dome and the large scale strike-slip faults of Sayan, Bolnay and Bogd. Several observations suggest a hot upper mantle beneath central Mongolia likely associated to a lithosphere thinning, that may also explain the anomalous elevation associated to the Hangay dome.
MOBAL experiment was divided into 3 phases:
The main participants were : Anne Deschamps : Géosciences Azur, CNRS, Nice, France. Jacques Déverchère, Julie Perrot : Domaines Océaniques, UBO/CNRS, Brest, France. Valentina Mordvinova, Alexandre Artemiev, Institute of the Earth Crust, Irkustk, Siberia. T. Dugarmaa, M. Ulziibat, Urtnassan, RCAG, Ulan Bator, Mongolia.
The period of observation was chosen from 25 April to 15 October 2003 to have the longer observation duration and avoid winter problems at the stations.
Sites have been recognized and prepared in 2002 (see report). The main instrumentation involved is the following:
Sensors : 1 CMG3ESP, 1 STS2, 1 CMG3T (all with a similar response at
120 sec) 3 CMG40 (response at 40 sec)
Sensors : 4 STS2, 1 CMG3T (all with a similar response at 120 sec) 7
CMG40 (response at 40 sec)
The location of the network was defined and sites have been prospected in summer 2002: 6 sites are in Siberia, 12 sites in Mongolia.
2 visits have been done to the instruments during the recording period. This work was taken in charge by Mongolian and Siberian colleagues. A visit consists mainly to test how the recorder is working, change the disk and write on the visit page all information necessary for the understanding of the data recorded.