GENERAL BULLETIN INFORMATION |
The Yemen National Seismic Network consist of the stations listed below which are operated by ( NSOC ) National Seismological Observatory Center (Geological Survey and Mineral Resources Board, Ministry of Oil and Minerals ) . |
|
Station
|
Latitude
|
Longitude |
Height (m) |
|
SANA |
15.387N |
44.205E |
2280 |
|
DHBB |
14.571N |
44.390E |
2460 |
|
ADEN |
12.776N |
44.983E |
41 |
|
BDHA |
13.975N |
45.567E |
2000 |
|
HAJJ |
15.699N |
43.599E |
1650 |
|
MARB |
15.464N |
43.992E |
1120 |
|
UDYN |
13.967N |
43.967E |
1370 |
|
TRBA |
13.231N |
44.115E |
1860 |
|
SADA |
16.933N |
43.750E |
1850 |
|
LBOS |
13.871N |
45.249E |
2325 |
|
MUKL |
14.476N |
49.036E |
41 |
|
RADA |
14.439N |
44.853E |
2353 |
|
ERIN |
14.230N |
44.230E |
1600 |
|
SMRH |
14.184N |
44.257E |
2990 |
|
ADDN |
14.353N |
43.850E |
2598 |
The location program currently used for locating earthquakes is HYPOCENTER ( Lienert et all, 1986 ). For locating local and regional seismic events layered model were assumed, while for locating distant earthquakes IASPEI travel time tables were used. The layered model used for local and regional seismic events is published by Egolff et al., 1990 . |
|
Depth of the layer (Km) |
P-wave Velocity ( Km/Sec) |
|
-2 |
3.4 |
|
0.5 |
4.2 |
|
2 |
6 |
|
12.5 |
6.2 |
|
27 |
6.8 |
|
28 |
7 |
|
58 |
8 |
The Vp/Vs ratio used in the layered model is 1.73.
Local magnitude ML is determined from maximum amplitude of the ground displacement of the seismic traces after making the proper corrections for the instrument type to simulate the output of the standardized Wood Anderson instrument. ML is calculated using XPITSA software for seismic analysis ( Scherbaum, F., and Johnson, J., 1992). |
The body wave magnitude Mb is calculated using the HYPOCENTER built in formula (Lienert R., 1994): |
Mb = log10  + Q( D, d) |
where A is the instrument corrected P-wave amplitude (nm) , T is the period ( sec ), and Q( D, d) is a distance - depth correction factor. |
No fixed depth or epicenter location used during the data analysis. Location of some events might be unrealistic such as zero depth earthquakes this is because of the limitation of the available data and reflect the location procedure and the velocity - depth model used. *Notice : There are Two Temprory stations ( HIMA and BRBR ) operated for short
period of time to monitor after shock activity. On the other hand the location of TRBA
station was slightly changed starting from the beginning of 2004 due to noise problem in
the old location.
|
Abbreviations: |
Month : month of the year |
Day : day of month |
Station : station code |
Phase : phase, The first characterizes onset E ( Emergent ) or I
( Impulsive ) and polarity U |
for Compress ional ) or D ( for Dilatation ). For the located events calculated phase is given. |
Arr. Time: first arrival of the wave to the station ( hh mm sec ). |
Mag : Local magnitude. |
Origin Time: the origin time of the located event ( yymmdd hhmm sec). |
Location : epicenter location of the event ( Latitude degree north , Longitude degree south ) |
Depth : the focal depth in kilometers. |
ML : Local Magnitude. |
Mb : Body Wave Magnitude. |
Mc : Coda Magnitude. |
