The seismic moment
tensor is a complete description of the earthquake
size and source geometry. The Centroid Moment Tensor (CMT) is a
reliable method
for calculating moment tensors (Dziewonski et al., 1981; Dziewonski and
Woodhouse, 1983; Dziewonski et al., 2000) based on fitting long period
surface
waves and ideally suited to study global seismicity. We use instead a
modified
algorithm (modeling intermediate-period surface waves) to compute
Regional CMTs
(RCMT; Arvidsson and Ekström, 1998; Ekström et al., 1998)
for
moderate-magnitude events, that are not well recorded at a global
scale. Our
main product is a routinely updated catalog of seismic moment tensors
for the
Euro-Mediterranean region.

The Alpine
Mediterranean region is characterized by complex
active tectonics, connected to the convergence between Africa and
Eurasia, but
also to the motion of several microplates, producing a wide range of
tectonic
regimes. The relevance of the RCMT Catalog therefore also lies in the
contribution that it can give to the understanding of the active
tectonics.

Seismicity in the
Mediterranean area is rather diffuse, in may
areas characterized by moderate energy release. Moderate-magnitude
events are
therefore particularly important because more widely spread than the
relatively
few larger-magnitude earthquakes. Small or moderate events are
difficult to
model at teleseismic distance with the classical Centroid Moment Tensor
(CMT)
method, owing to the low signal-to-noise ratio of the long period body
waves
used. The inversion of intermediate period surface waves recorded at
regional
distance, as done in RCMTs, allows instead to compute moment tensors
also for
these events with reliability comparable to the standard CMT analysis.

We compute Regional
Centroid Moment Tensors (RCMT) routinely since 1997 for earthquakes,
with
magnitude approximately betweeen 4.5 and 5.5, occurring in the
Euro-Mediterranean region (see also Morelli et al., 1998; Pondrelli et
al., 1999
and 2001), and we maintain a catalog of solutions. Our catalog
occasionally
also lists events with magnitude as low as 4.0, in cases where the
station
distribution is particularly favorable. All data can be downloaded at
the European-Mediterranean RCMT site
or from this CD. The
catalog generally does not include larger events, which can instead be
found in
the global CMT Catalog maintained at Harvard. The
European-Mediterranean Regional
Centroid Moment Tensor Catalog is a joint project between scientists
from **Istituto
Nazionale di Geofisica e Vulcanologia** (Rome, Italy) and **Harvard
University** (Cambridge, MA,
USA).

__Please
reference these data as__:

** **

Pondrelli, S., A.
Morelli, G. Ekström, S. Mazza, E. Boschi, and A. M. Dziewonski,
2002,
European-Mediterranean regional centroid-moment tensors: 1997-2000, *Phys.
Earth Planet. Int.*, **130**, 71-101.

Pondrelli S., A.
Morelli, and G. Ekström, 2004, European-Mediterranean Regional
Centroid Moment
Tensor catalog: solutions for years 2001 and 2002, *Phys. Earth
Planet. Int, ***14**, 127-147.

**References**

Arvidsson,
R.,
Ekström, G., 1998. Global CMT analysis of moderate earthquakes Mw
> 4.5
using intermediate period surface waves. Bull. Seismol. Soc. Am. 88,
1003Ü1013.

Dziewonski,
A.M.,
Chou, T.A., Woodhouse, J.H., 1981. Determination of earthquake source
parameters from waveform data for studies of global and regional
seismicity. J.
Geophys. Res. 86, 2825-2852.

Dziewonski,
A.M.,
Woodhouse, J.H., 1983. An experiment in the systematic study of global
seismicity; centroid moment tensor solutions for 201 moderate and large
earthquakes of 1981. J. Geophys. Res. 88, 3247-3271.

Dziewonski,
A.M.,
Ekström, G., Maternovskaya, N.N., 2000. Centroid-moment tensor
solutions for
October-December 1999. Phys. Earth Planet. Inter. 121, 205-221.

Ekström,
G., Morelli, A.,
Boschi, E., Dziewonski, A.M., 1998. Moment tensor analysis of the
central Italy
earthquake sequence of September-October 1997. Geophys. Res. Lett.
25,
1971-1974.

Morelli,
A., Ekström,
G., Olivieri, M., 2000. Source properties of the 1997-1998 Central
Italy
earthquake sequence from inversion of long-period and broad-band
seismograms.
J. Seismol. 4, 365-375.

Pondrelli,
S.,
Ekström, G., Morelli, A., Primerano, S., 1999. Study of source
geometry for tsunamigenic
events of the Euro-Mediterranean area. In: International Conference on
Tsunamis. UNESCO Books, Paris, pp. 297-307.

Pondrelli,
S.,
Ekström, G., Morelli, A., 2001. Seismotectonic re-evaluation of
the 1976
Friuli, Italy, seismic sequence. J. Seismol. 5, 73-83.