RECENT EARTHQUAKE ACTIVITY IN NORTH WEST LIBYA
Khaled Saleh Dhedah
Earth Science Department, Faculty of Science - Gharian
University of Al –Jabal Al- Gharbi- Libya
Mobile: +00218926760166 - b.o.box no 64500 Gharian
Email: khaleddhedah@hotmail.com
ABSTRACT
Libya located at the northern outermost of the African continent, has
caused a complex crustal structure which are composed of a series of
basins
and
uplifts,
faulting,
subsidence
and
tilting.
The
westernmost
feature of the Sirt basin is the NW-SE trending Hun Graben, a traditional
example of well-exposed normal block faulting. This graben is seismically
active and was the site of several large earthquakes in the 1930s, including
an earthquake of magnitude 7.1 (1935 April), one of the largest historical
events on the African content, this shock was located in Al Qaddahiya
about 100 km south of Misratah, followed by a very large number of
aftershocks including two of magnitudes 6.0 and 6.5 on the Richter scale.
In 1941a major of magnitude 5.6 hit the Hun Graben area. In 1939 an
earthquake of magnitude 5.6 occurred in the Gulf of Sirt area, followed by
a
number
of
aftershocks.
The
major
tectonic
elements
present
are
characterized by different trends. Northwest – Southeast trend, this trend is
parallel to the red sea, and it is well obvious in Hun Graben. This study
represents a detailed investigation that aims to concentrate on the recent
earthquake activity and its implications on the earthquake hazards in the
area. This study is primarily based on the recorded data from the recently
established
Libyan
National
Seismograph
Network
(LNSN)
and
integrating with
other
available
geological
and
geophysical
information.
Earthquakes
are
significant
natural
hazard
in
many
regions,
with
dangerous
effects
on
the
society
and
communications,
transportation,
roads and rail network. Appraisal of earthquake occurrence parameters for
any area plays an important role in confirm measures to minimize
earthquake damage and in predict the future risk during development for
planned projects. Recently (between 2006 and 2010) the LNSN has
recorded substantial seismic activity in the northwest part of Libya, with
most of these activity in south and north of the city of Misratah, and along
Eastern
flank of hun graben and extended
to offshore Tripoli area .These
earthquakes have been studied by LNSN. The recorded waveform data
were analyzed using seisan software in order to obtain the earthquake
parameters. Misratah earthquake have been occurred on 11/11/2006 with
3.3Ml, It is located in the south city of Misratah (lat. 31.483 E and Long.
14.787 N) very close to Al Qaddahiya city, Another earthquake occurred
on 06/12/2006 with 2.4Ml, It is located in the south city of Misratah (lat.
31.336 E and Long. 14.892 N). The earthquake data were plotted on maps
to give an overview on the seismic activity in northwest Libya. It is
strongly suggested that this recent earthquake activity is particular in
seismic hazard evaluation for northwest Libya.