SEISMICITY AT WHITE ISLAND VOLCANO, NEW-ZEALAND - A REVISED CLASSIFICATION AND INFERENCES ABOUT SOURCE MECHANISM

Citation
S. Sherburn et al., SEISMICITY AT WHITE ISLAND VOLCANO, NEW-ZEALAND - A REVISED CLASSIFICATION AND INFERENCES ABOUT SOURCE MECHANISM, Journal of volcanology and geothermal research, 83(3-4), 1998, pp. 287-312
Citations number
35
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Geosciences, Interdisciplinary
ISSN journal
0377-0273
Volume
83
Issue
3-4
Year of publication
1998
Pages
287 - 312
Database
ISI
SICI code
0377-0273(1998)83:3-4<287:SAWIVN>2.0.ZU;2-3
Abstract
The classification of earthquakes at White Island volcano, New Zealand , has been revised to address problems in existing classification sche mes, to better reflect new data and to try to focus more on source pro cesses. Seismicity generated by the direct involvement of magmatic or hydrothermal fluids are referred to as volcanic, and that generated by fault movement in response to stresses caused by those fluids, region al stresses, thermal effects and so on are referred to as volcano-tect onic. Spasmodic bursts form a separate category, as we have insufficie nt information to classify them as volcanic or volcano-tectonic. Volca nic seismicity is divided into short-duration, long-period volcanic ea rthquakes, long-duration volcanic earthquakes, and harmonic- and non-h armonic volcanic tremor, while volcano-tectonic seismicity is divided into shallow and deep volcano-tectonic earthquakes. Harmonic volcanic tremor is related to sub-surface intrusive processes, while non-harmon ic volcanic tremor originates close to active craters at shallow depth , and usually occurs during eruptive activity. Short-duration, long-pe riod volcanic earthquakes come from a single source close to the activ e craters, but originate deeper than non-harmonic volcanic tremor, and are not related to eruptive activity. Long-duration volcanic earthqua kes often accompany larger discrete eruptions. The waveform of these e vents consists of an initial low-frequency part from a deep source, an d a later cigar-shaped part of mixed frequencies from a shallow crater source. (C) 1998 Elsevier Science B.V. AU rights reserved.