Evidence of Holocene and historical changes of sea level in the Langkawi Islands

About eighty radiometrically dated biogenic and morphological indicators of sea level of the Langkawi Islands prove that since the maximum Mid-Holocene inundation, the paleo-sea surface descended stepwise thrice to reach its current position several hundred years ago. In presumably historical time some parts of the island group were raised between 0.5 and one meter. One of such events was related to the Aceh/Simeulue mega-earthquake of December 2004 which caused live bands of rock-clinging oysters and barnacles to shift 30 to 40 centimeters upward at Teluk Burau. GPS study also yields evidence of 9 to 11 millimeters co-seismic uplift of the northwestern sector of Peninsular Malaysia. The anomalously high sea stands in the early part of the Holocene and latest Pleistocene in northwestern Peninsular Malaysia remain the most outstanding issue in this investigation. Comparison with recently published sea-level curves of the Sunda Shelf strongly suggests that the geoid of the Strait of Malacca was 50 to 40 meters higher in the period of the LGM (Last Glacial Maximum: 21 ka to 19 ka) to the early half of the Holocene at 10 ka to 5 ka. In the early period of the Holocene, sea level was still up to 24 meters higher than over the Sunda Shelf