OSL dating of tsunami deposits from Phra Thong Island, Thailand

To evaluate the potential of optical dating (OSL) in establishing a proper tsunami chronology for Phra Thong Island (SW Thailand), the method was applied to a suite of tsunamigenic and littoral sandy deposits, for which independent age control was available. Small aliquots of coarse grained quartz were used for measurements, and processed statistically by means of appropriate age models. Based on the equivalent dose distributions, the well bleached littoral deposits were analysed with the central age model (CAM); the tsunamigenic samples revealed poor bleaching, thus, the minimum age model (MAM) was applied. The cross-check with independent age data showed good agreement between luminescence ages and the existing radiocarbon chronology for the littoral deposits. The poorly bleached deposits of the 2004 Indian Ocean tsunami revealed residuals of less than 40 years, which are insignificant for older deposits and demonstrate the general suitability of the dating technique for tsunamites on Phra Thong. Afterwards, the approach was extended to tsunamigenic and littoral sediments of unknown age. Since those revealed properties similar to their reference deposits, the procedures of statistical De determination were adopted. The resulting ages were in agreement with the stratigraphical position and (largely) with the wider chronological context.

► OSL was applied to tsunamigenic and littoral sandy deposits from Thailand.
► Age model selection (CAM or MAM) was based on De distributions.
► Independently 14C-dated littoral deposits were well bleached and analysed with CAM.
► Poorly bleached 2004 tsunami deposits revealed residuals <40 years with MAM.
► Palaeotsunami deposits without age control were dated to 500 and 1000 years, respectively.