Focus Earth
The Izmit Earthquake:
A Quick Post-Seismic Analysis with
Satellite Observations
M. Barbieri, J. Lichtenegger & G. Calabresi
Earth Observation Department, ESRIN, Frascati, Italy
Buildings were razed to the ground and electric
and telephone lines cut in Izmit, in northwest
Turkey, by the strong earthquake that shook
the region on 17 August 1999. The National
Earthquake Information Centre reported a
quake of magnitude 7.8, almost as strong as
the 7.9-magnitude San Francisco quake that
claimed 700 victims in 1906. In Turkey, four
days after the event, the death toll had risen to
more than l0 000, with 45 000 reported injured
and thousands of people still missing.
The earthquake’s epicentre was identified as
being between Izmit and Bursa (Fig. 1), about
100 km east of Istanbul. High casualty figures
were reported not only in Golcuk, but also in
the towns of Derince and Darica, both situated
to the west of Izmit. The large town of
Adapazari, northeast of Sapanca Lake, was
also severely damaged by the quake.
Since this devastating first shock, there has
been a second series of tremors further east,
but along the same fault line, peaking on
12 November and bringing death and destruction
to the towns of Kaynashli and nearby Duzce.
Geological setting of the area
Turkey’s North Anatolian Fault Zone (NAFZ) is
the most active in the country. Historically, it is
here that most of the biggest earthquakes have
originated. The NAFZ zone splays out into three
strands at about 30.5 deg E. The northern
strand crosses the Bay of Izmit and the
Marmara Sea, and reappears in the Gulf of Saros.
Many researchers believe that the Marmara Sea
region is a depression that is slowly widening,
due to two fault systems running in parallel.
The tectonic activity in the area is basically
explained by movements of the Eurasian,
Arabic and African plates activating different
portions of the Anatolian fault system (Fig. 2).
The NAFZ is a close analogue of the San
Andreas fault in California. Both structures are
active, have similar slip rates, lengths and
straightnesses, but earthquakes occur five
times more frequently in the NAFZ (M > 6.7!).
focus earth
Figure 1. Geographical map
of the earthquake area
