Studies of the Coastal Morphology on Surtsey Island

Book excerpt: Investigations on the shore and offshore morphology of the volcanic island of Surtsey off the southeastern coast of Iceland are reported. The volcanic activity that started as a submarine explosion in November 1963 ended in June 1967. A photogrammetric map of the island is in preparation. During the winter 1967/68 there was a rapid retreat of the lava cliff on the southern coast. The cliff is 10-15 m in height. The maximum retreat was 140 m and the average retreat about 75 m. The amount of lava removed by erosion is estimated at 2 million cubic meters. The shoals of former cinder-cone islands (Surtla, Syrtlingur, and Jolnir), contemporaneously built up, were found to have been abraded during the last winter. The plateaus of Jolnir and Surtla had been lowered several meters. The submarine slopes of Surtsey were investigated by SCUBA diving down to a maximum of 40 m in depth. The sandy material of the slopes of the northern point is deposited at the frictional angle of repose. There is active avalanching on these slopes. On the slopes of the southern coast angular blocks dominate. (Author).