NEHRP Site Classification and Preliminary Soil Amplification Maps of Lamphun City, Northern Thailand

Abstract

The primary goal of this study is to generate the NEHRP soil classification map for Lamphun City using the average shear wave velocity values (Vs(30)) derived from the multi-channel analysis of surface wave (MASW) data. The secondary goal is to use the Vs(30) data to create the preliminary site amplification map of the city. For this work, multi-channel surface wave seismic data were acquired at 48 preselected sites in the Lamphun City area, northern Thailand. After generating the NEHRP map, soil class D is found to be present mostly in the northern part of the area, while soil class C is found mostly in the southern part. A major part of the Lamphun City is located on soil class D. The soil amplification map indicates higher amplification in the east, north and west of the city, where the soils consisted of mostly soft sediments from the alluvial plain and river terrace. The central and south eastern parts of Lamphun City had a relatively low amplification, perhaps because the sediment in this part is relatively thin or the bedrock is shallow. The results of study imply that the major part of Lamphun city may experience earthquake ground shaking due to amplification of the soft soils.

Keywords

• masw
• nehrp
• shear wave velocity
• soil amplification