LOCAL SITE RESPONSE ON SIMULATED STRONG EARTHQUAKE MOTION AT LAEM CHABANG PORT, THAILAND

Abstract

Laem Chabang port, located in Chonburi province in the upper Gulf of Thailand, is similar to many of the ports around the world. Some areas of Leam Cha bang port were layered by backfill materials which are highly suspected to soil liquefaction phenomena from the moderate to strong earthquakes. After one of the world’s largest earthquakes of December 26th, 2004 (Magnitude 9.1) occurred in the region off the west coast of northern Sumatra, various existing active faults have been reported to have more potential to generate future earthquakes. Among those active faults, Ranong and Khlong Marui fault zone, distributed around the south and the upper Gulf of Thailand, have been evidenced to have more seismic activities than December 2004. The closet distance between Leam Chabang port and the extension of Ranong fault zone to the upper Gulf of Thailand is approximately 180-200 km. Though not too close, it is still probable to generate strong earthquakes. This study, for that reason, aims to investigate the local site responses of the filled area at Laem Chabang port due to afresh seismic Ranong active fault by employing the equivalent linear ground response analysis. The complete strong earthquake motion time history from the Ranong fault would be synthetically generated and inputted as a bedrock motion underneath the site of interest. The simplified analysis of liquefaction potential assessment based on the results from local site response would be additionally adopted to evaluate the liquefaction susceptibility around this site. The simulation results indicated that some backfill soil layers which have the very low SPT N-value were significantly suspected to liquefy under strong earthquake motions.

Keywords: Local site response, synthetic accelerogram, liquefaction potential, backfill, Laem Chabang port