Volcanic activity on White Island, Bay of Plenty, 1966–69

Abstract

Abstract White Island, an andesitic volcano, has been erupting ash intermittently since November 1966. A precise level net of 14 stations was installed in July 1967. The net has been relevelled five times since. The first relevel, 3 months after installation, showed that an asymmetric bulge had developed in the crater floor. Three months later a fumarole developed as a new ash vent and copious eruptions of ash occurred. Later releveis showed marked subsidence near the new vent. It is considered that the bulge represented inflation prior to ash eruption, that at the time of ash eruption magma lay not far below the crater floor, and that the later subsidence represents deflation.