Saudi Arabian Broadband Array

Summary

Introduction

From November 1995 to March 1997 a total of nine broadband temporary stations were deployed across the Saudi Arabian shield. These stations consisted of STS-2 seismometers recorded continuously at 40 sps on REFTEK dataloggers. All installations were at bedrock sites. The results from our field deployment of nine portable broadband stations suggest that sites in the Arabian shield are extremely quiet. Using data sections selected randomly during the deployment, noise studies showed that most stations were exceptionally quiet with noise levels near the USGS Peterson (1993) low noise model for frequencies higher than 0.1 Hz. At lower frequencies, the horizontal components showed increased noise levels, possibly due to instrumental characteristics. High-frequency ( > 1 Hz) noise varied as much as 10 dB between day and night for some stations (RAYN, TAIF) while more isolated stations (HALM) were constant. Seasonal noise levels also varied, with April to June being the quietest months. Slight changes in peak microseism frequency also occurred seasonally. The quietest stations were HALM, RAYN, AFIF and UQSK, all of which were located in central Saudi Arabia and showed noise levels near the low noise model for frequencies between 0.1 and 4 HZ. The optimal site for a new station would be near HALM as it was both quiet and showed very little diurnal variation due to cultural noise.

The low noise at these stations also contributes to the very low detection threshold of events with mb = 3.5 at distances from 10 to 100 degrees. These stations appear to be among the best sites in the world for the properties of detection thresholds and ground noise levels. Seismograms from sources 10 degrees from the center of the network have unique characteristics which can be used to identify the source regions. Zagros events have a clear Pn and Sn arrivals with an observable Lg. Shallow events from the Arabian Sea have clear P, S, and surface waves but no discernible Lg phases. From the opposite direction, aftershocks from the Gulf of Aqaba have very weak P and S waves with very strong Lg phases.

Station Map

Station map

Station List

(plain text version)

sta ondate offdate lat lon elev staname statype refsta dnorth deast
AFIF 1995001 – 23.931 43.04 1.116 Afif, Saudi Arabia ss HALM 121.2775 -129.8206
BISH 1995001 1996071 19.9228 42.6901 1.379 Bisha, Saudi Arabia ss HALM -324.0641 -170.17
HALM 1995001 – 22.8454 44.3173 0.93 Hadabat Al-Mahri, Saudi Arabia ss HALM – –
RANI 1995001 – 21.3116 42.7761 1.001 Raniyah, Saudi Arabia ss HALM -169.7276 -159.6634
RAYN 1995001 1996160 23.522 45.5008 0.792 Ar-Rayn, Saudi Arabia ss HALM 75.7196 120.6603
RAYN 1996161 – 23.5225 45.5032 0.631 Ar-Rayn, Saudi Arabia ss HALM 75.7772 120.9045
RIYD 1996069 – 24.722 46.643 0.717 Riyadh, Saudi Arabia ss HALM 210.5587 234.9251
SODA 1995001 – 18.2921 42.3769 2.876 Al-Soda, Saudi Arabia ss HALM -505.0186 -205.0602
TAIF 1996150 – 21.281 40.349 2.05 Taif, Saudi Arabia ss HALM -168.5365 -411.1522
UQSK 1996161 – 25.789 42.36 0.95 Uqlat Squoor, Saudi Arabia ss HALM 328.6509 -196.0379

Total: 10

Channel List

(plain text version)

sta chan ondate chanid offdate ctype edepth hang vang descrip
AFIF BHE 1995001 2082 – n -0 90 90 –
AFIF BHN 1995001 2083 – n -0 0 90 –
AFIF BHZ 1995001 2084 – n -0 0 0 –
BISH BHE 1995001 2085 1996071 n -0 90 90 –
BISH BHN 1995001 2086 1996071 n -0 0 90 –
BISH BHZ 1995001 2087 1996071 n -0 0 0 –
HALM BHE 1995001 2088 – n -0 90 90 –
HALM BHN 1995001 2089 – n -0 0 90 –
HALM BHZ 1995001 2090 – n -0 0 0 –
RANI BHE 1995001 2091 – n -0 90 90 –
RANI BHN 1995001 2092 – n -0 0 90 –
RANI BHZ 1995001 2093 – n -0 0 0 –
RAYN BHE 1995001 2094 1996160 n -0 90 90 –
RAYN BHE 1996161 2095 1997032 n 0 90 90 –
RAYN BHN 1995001 2096 1996160 n -0 0 90 –
RAYN BHN 1996161 2097 1997032 n 0 0 90 –
RAYN BHZ 1995001 2098 1996160 n -0 0 0 –
RAYN BHZ 1996161 2099 1997032 n 0 0 0 –
RIYD BHE 1996069 2100 – n -0 90 90 –
RIYD BHN 1996069 2101 – n -0 0 90 –
RIYD BHZ 1996069 2102 – n -0 0 0 –
SODA BHE 1995001 2103 – n -0 90 90 –
SODA BHN 1995001 2104 – n -0 0 90 –
SODA BHZ 1995001 2105 – n -0 0 0 –
TAIF BHE 1996150 2106 – n -0 90 90 –
TAIF BHN 1996150 2107 – n -0 0 90 –
TAIF BHZ 1996150 2108 – n -0 0 0 –
UQSK BHE 1996161 2109 – n -0 90 90 –
UQSK BHN 1996161 2110 – n -0 0 90 –
UQSK BHZ 1996161 2111 – n -0 0 0 –

Total: 30

Selected References

URL: http://eqinfo.ucsd.edu/deployments/saudi_arabia.php [Last updated: 2006-10-26 (299) 22:47:09 UTC]