During the Taisho Eruption (1914-1915) of Sakurajima Volcano, the Secondary Lava Flows drained out from the front of the primary lava flows after a certain pause from their settlement. We investigate distribution, timing and conditions of the effusion of the Secondary Lava Flows which have not been clarified yet. We define the features of the Secondary Lava Flows by means of geomorphological interpretation using aerial photographs and field survey. More than 200 landscape photographs, which were taken at the time of the Taisho Eruption, indicate that the earliest Secondary Lava Flows effused on 14 February 1914; this date was several months earlier than those previously considered. The effusing of the Secondary Lava Flows did not occur as a single event but as several events in different areas. Based on volumetric estimation of the individual Secondary Lava Flows, the volume of the Secondary Lava Flows tend to have increased as time passed after the eruption. The Secondary Lava Flows effused from the underlying tip of river valleys.
Keywords: Sakurajima volcano, Taisho Eruption, Secondary Lava Flows, aerial photographs