Landscape Geology of Subaqueous Volcanic Rocks: Sea Cliffs on Etomo Peninsula, Muroran, Hokkaido, Japan

Abstract

“Buratamori Muroran, ” an NHK Japan TV program was broadcasted on November 25, 2017. To prepare for the program, observations were made on the Etomo Peninsula using orthophotographs provided by Muroran City as Open Data. A large number of aerial photographs were taken using aircrafts and observational research was undertaken by road. In addition, cliffs were observed from a small boat provided by Hokkaido Regional Development Bureau, Muroran. As a result of these research activities, many remarkable outcrops and occurrences of Miocene subaqueous volcanic rocks were observed on the cliffs, most of which are inaccessible. Subaqueous pumice flows, concentric and radial columnar jointed dikes called Peach Rock, subaqueous lava domes associated with hyaloclastites, and their feeder dikes forming apophyseal, polygonal and columnar-joints were observed. The occurrences of these variable subaqueous volcanic rocks are described and models of some volcanic rocks are described. Finally, cliffs are defined as subjects for geo-tourism.