General information about seismicity & seismotectonics in Libya - IRIS

General information about seismicity &
seismotectonics in Libya
Presented by Eng. Abdala Elmelade
Libyan Center for Remote Sensing & Space Science (LCRSSS)
Libyan National Seismological Network (LNSN)
IRIS Metadata Workshop
'Managing Waveform Data and Related Metadata for Seismic Networks'
Kuwait City, Kuwait
January 14–18, 2013

LIBYAN NATIONAL SEISMOLOGICAL NETWORK
Dep.
Maintenance
and field
operations
Seismological Office
Dep. Data
processing and
analysis
Dep. Scientific
researchs and
filed studies

NETWORK STATIONS
Elevation (m) Longitude Latituude Station code Station name
073 11.614E 32.843N ASA ةﺓسﺱعﻉلﻝاﺍ
600 09.442E 30.017N GHD سﺱمﻡاﺍدﺩغﻍ
709 13.086E 32.122N GHR نﻥاﺍيﻱرﺭغﻍ
049 20.198E 30.913N JDB اﺍيﻱبﺏاﺍدﺩجﺝإﺇ
351 15.813E 29.102N JFR ةﺓرﺭفﻑجﺝلﻝاﺍ
413 23.212E 24.161N KFR ةﺓرﺭفﻑكﻙلﻝاﺍ
408 20.876E 32.582N MRJ جﺝرﺭمﻡلﻝاﺍ
114 15.008E 32.313N MSR هﻩتﺕاﺍرﺭصﺹمﻡ
429 14.248E 29.987N SHF فﻑرﺭيﻱوﻭشﺵلﻝاﺍ
095 16.658E 31.081N SRT تﺕرﺭسﺱ
139 23.921E 32.056N TBQ قﻕرﺭبﺏطﻁ
100 13.031E 32.526N AZZ ةﺓيﻱزﺯيﻱزﺯعﻉلﻝاﺍ
095 21.303E 29.119N UJL هﻩلﻝجﺝوﻭأﺃ
474 14.752E 26.138N UMB بﺏنﻥاﺍرﺭأﺃلﻝاﺍ مﻡأﺃ
239 17.561E 28.554N ZLA هﻩلﻝزﺯ

ONE OF REMOTE STATIONS

REMOTE SITE DESIGNS

Three component broad band Trillium seismometers (40 second period) installed at
12 of the sites whereas a three component very broad band STS-2 seismometer
(120 second period) installed at the other 3 sites. Trident 24-bit, 142dB dynamic
range digitizer, is programmable front end gain to support a wide range of sensor
types.

NaqsServer is a Nanometrics data acquisition system designed to receive,
process, and store serial data, seismic data, and state-of-health information, and
process calibration commands.
Cygnus transciever transmits and receives data to the acquisition center via a
satellite link. It includes a high precision GPS timing subsystem, two serial data
input ports, an Ethernet port for external access, a satellite modem for both
inbound and outbound satellite links.

Recorded data is accessible through a local network by a number of analyzing
computers; Atlas and Seisan software are used to process and analyze data. Raw
and analyzed data are archived in server computers and hard disks.
Two server computers are used for data archiving:
1. Complete row data.
2. Detected events data.

An earthquake of December 29 th , 2009, with ML =4.8

AN EARTHQUAKE OF DECEMBER 29 TH , 2009, WITH ML =4.8
2009-12-29 11:08:54.1 L 32.514 14.986 4.1 4.8ML
STATUS: [PR] (hipo: LYB | mag: LYB | mod: )
Region: (Reference: 16km N-NW Misratah, aprox.)
ErOt20.1 s AxMax 64.5 km AxMin 35.2 km ErDep 52.8 km no 12 Gap 170° Rms 8.8
GHD
ASA
GHR
SHF
MSR
UMB
JFR
SRT
ZLA
JDB
MRJ
KFR

TAURUS PORTABLE SEISMOLOGICAL STATIONS USED FOR
SPECIAL STUDIES.

TEMPORARY PORTABLE STATION SITE

Ò Tectonics:
Ò The structural weakness of the area is exemplified by alternating
periods of uplift and subsidence originating in late Precambrian
time, historically it is considered to be a mid-Paleozoic event.
Ò Alternatively proposed that dextral shear forces dominated this
period of deformation in the Sarir arm.

OFFSHORE TECTONIC ELEMENTS.

HISTORICAL AND INSTRUMENTAL SEISMICITY DATA OF ISC – PDE –
EMSC 1907 – 2005, MAGNITUDE OF 2.6 – 7.1

Ò Earthquakes activity, is concentrated in the following regions:
Ò 1. The offshore of Tripoli and Azizia fault.
Ò 2. Hun Graben region.
Ò 3. Al-Jabal Al-Akhdar East of Libya.

1. THE OFFSHORE OF TRIPOLI & AZIZIA FAULT
Ò The offshore of Tripoli is
considered to be active, an
earthquake of 5.7 magnitude was
recorded in 1974 about 50km
offshore of Tripoli. Recent
Seismicity showed in 2009, a 4.8
magnitude earthquake offshore of
Misuratha (30 km).

2. HUN GRABEN AREA
Ò The biggest earthquake magnitude
was at Hun Graben area in
19/4/1935, 7.1 magnitude was felt
at a distance of more than 200km,
as far as Tripoli.
Ò Recent Seismicity showed
considerable earthquake activity,
for example a number of events of
magnitudes 3.6 were recorded by
the local seismological network in
that area.

3. AL-JABAL AL-AKHDAR EAST OF LIBYA.
Ò The other destructive earthquake
was at Old Marje City (Al-Jabal
Al-Akhdar ). In 1963, a
magnitude of 5.8 earthquake
occurred in the region. The city
was damaged completely
because of the site effects
(alluvial soils and the shallow
water table ). About 600 peoples
reported killed.

SEISMICITY OF LIBYA, ONLY EVENTS OF 2.0 – 2.5 SHOWN

SEISMICITY OF LIBYA, ONLY EVENTS OF 2.5 – 3.0 SHOWEN

SEISMICITY OF LIBYA, EVENTS OF ONLY 3.0 – 3.5 ARE
SHOWN

SEISMICITY OF LIBYA, EVENTS OF ONLY 3.5 – 4.0 ARE SHOWN

SEISMICITY OF LIBYA, EVENTS OF ONLY 4.0 – 4.8 ARE SHOWN

FOCAL MECHANISM OF THE, 29-12-2009, 11:08:54.1 ML =
4.8

CONCLUSION
1. Most of the seismological activity is concentrated in the north part of
Libya.
2. Geological information and historical and recent seismicity show that
Hun graben area is the most active and hazards region because of its
location near to the big cities (Musurath, Tripoli), where the more dance
population and most important industrial activity is concentrated.
3. Geological information, historical and recent seismicity in Al-Jabal Al-
Akhdar area also show a very high seismological activity, and the region
is also hazards because of the location of the second biggest city
(Bengazi) in Libya, some seismological activity is related to the
subduction region at Crete island offshore of Al-Jabal Al-Akhdar .
4. The south part of Libya has also some seismological activity, but due to
the desertation and wide spread of cities the hazard could be less
important.

THANK YOU FOR YOUR
ATTENTION