Geophysical Research Abstracts, Vol. 9, 00893, 2007
SRef-ID: 1607-7962/gra/EGU2007-A-00893
© European Geosciences Union 2007
New insights for the Tabriz fault (NW Iran) from GPS
profiles measurements
profiles measurements
S. Van Gorp (1), J. Chéry (1), F. Masson (1,2), Y. Djamour (3), H. Nankali (4)
(1) Laboratoire Dynamique de la lithosphère, CNRS / Université Montpellier 2 - Montpellier,
FRANCE (vangorp@dstu.univ-montp2.fr, +33 467 144 591), (2) IPG, EOST, CNRS /
Université Louis Pasteur - Strasbourg, FRANCE, (3) National Cartographic Center - Tehran,
IRAN
The Tabriz region (NW of Iran) is located East of the North Anatolian Fault (NAF)
and West of the relatively aseismic South Caspian basin. To the North, The Caucasus
is supposed to accommodate 8 +/- 1 mm/yr of NNE/SSW shortening. The rigid block
of Central Iran limits the zone to the South. The region is crossed by large WNW-ESE
faults, known for major M>6.5 earthquakes with an average recurrence time of 250
years. Large scale velocity field from GPS measurements suggested about 8mm/yr of
right-lateral displacement for the faults in the region. In a recent study, we presented
the analysis of the measurements of a dense GPS network installed in NW Iran in
2002. Those results showed that most of the 8 mm/yr right-lateral motion is accommodated
by the Tabriz fault. This fault is known as the major active fault of the NW
Iran. It has an average strike of N120 over a length of about 150 km. This fault generated
two large earthquakes in 1721 (M=7.3) and 1780 (M=7.4) that strongly damaged
the city of Tabriz (1.2 million people). It did not generate any earthquake for 200 years.
In order to study the seismic cycle of this fault, two GPS profiles were installed normal
to the fault in 2004. Each profile is about 80 km long and comprises 8 sites. Here, we
present results obtained after 2 years and 3 campaigns of measurements. Implications
for the deep structure of the Tabriz fault are also proposed
is supposed to accommodate 8 +/- 1 mm/yr of NNE/SSW shortening. The rigid block
of Central Iran limits the zone to the South. The region is crossed by large WNW-ESE
faults, known for major M>6.5 earthquakes with an average recurrence time of 250
years. Large scale velocity field from GPS measurements suggested about 8mm/yr of
right-lateral displacement for the faults in the region. In a recent study, we presented
the analysis of the measurements of a dense GPS network installed in NW Iran in
2002. Those results showed that most of the 8 mm/yr right-lateral motion is accommodated
by the Tabriz fault. This fault is known as the major active fault of the NW
Iran. It has an average strike of N120 over a length of about 150 km. This fault generated
two large earthquakes in 1721 (M=7.3) and 1780 (M=7.4) that strongly damaged
the city of Tabriz (1.2 million people). It did not generate any earthquake for 200 years.
In order to study the seismic cycle of this fault, two GPS profiles were installed normal
to the fault in 2004. Each profile is about 80 km long and comprises 8 sites. Here, we
present results obtained after 2 years and 3 campaigns of measurements. Implications
for the deep structure of the Tabriz fault are also proposed
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