Report on Whakaari/White Island (New Zealand) — December 1977
Natural Science Event Bulletin, vol. 2, no. 12 (December 1977)
Managing Editor: David Squires.
Whakaari/White Island (New Zealand) Seismogram analyses for 30 August-15 November
Please cite this report as:
Global Volcanism Program, 1977. Report on Whakaari/White Island (New Zealand) (Squires, D., ed.). Natural Science Event Bulletin, 2:12. Smithsonian Institution.
37.52°S, 177.18°E; summit elev. 294 m
All times are local (unless otherwise noted)
White Island seismograms for the period 30 August-15 November were analyzed (table 1). [About 2,700] small volcanic earthquakes have been counted and separated into four groups [for which the magnitude-frequency coefficient b was determined.] All the events interpreted as explosion earthquakes occurred during a [strong] swarm of A-type quakes between 1722 on 21 October and 0724 on 22 October. The largest, ML 2.6, occurred at 0104. [An eruption is known to have taken place between 9 October and 10 November (date unknown). From the explosion earthquakes, J.H. Latter suggests that the peak of this activity probably occurred at 0104 on 22 October.]
|Number of Events||Earthquake Type|
|873||Minakami B-type (low-frequency) produced in or very close to magma or in areas of hot gas.|
|218||Intermediate-frequency ["C-type"]. Generally closely associated with periods of volcanic tremor [which has a dominant frequency of 2.5-3.5 Hz, but sometimes as high as 4-5 Hz.]|
Geological Summary. The uninhabited Whakaari/White Island is the 2 x 2.4 km emergent summit of a 16 x 18 km submarine volcano in the Bay of Plenty about 50 km offshore of North Island. The island consists of two overlapping andesitic-to-dacitic stratovolcanoes. The SE side of the crater is open at sea level, with the recent activity centered about 1 km from the shore close to the rear crater wall. Volckner Rocks, sea stacks that are remnants of a lava dome, lie 5 km NW. Descriptions of volcanism since 1826 have included intermittent moderate phreatic, phreatomagmatic, and Strombolian eruptions; activity there also forms a prominent part of Maori legends. The formation of many new vents during the 19th and 20th centuries caused rapid changes in crater floor topography. Collapse of the crater wall in 1914 produced a debris avalanche that buried buildings and workers at a sulfur-mining project. Explosive activity in December 2019 took place while tourists were present, resulting in many fatalities. The official government name Whakaari/White Island is a combination of the full Maori name of Te Puia o Whakaari ("The Dramatic Volcano") and White Island (referencing the constant steam plume) given by Captain James Cook in 1769.
Information Contacts: J. Latter, DSIR, Wellington.