PERMANENT LAVA LAKES - OBSERVED FACTS AND INDUCED MECHANISMS

Authors
Citation
H. Tazieff, PERMANENT LAVA LAKES - OBSERVED FACTS AND INDUCED MECHANISMS, Journal of volcanology and geothermal research, 63(1-2), 1994, pp. 3-11
Citations number
10
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Geology
ISSN journal
0377-0273
Volume
63
Issue
1-2
Year of publication
1994
Pages
3 - 11
Database
ISI
SICI code
0377-0273(1994)63:1-2<3:PLL-OF>2.0.ZU;2-D
Abstract
Permanent lava lakes are a quite unusual eruptive feature. Only half a dozen have so far been discovered and more or less closely studied. O nly two presently exist. Lava lakes (that differ basically from tempor ary lava ponds or lava pools) are of great significance because they a llow close observations of important phenomena accompanying volcanic e ruptions that cannot be studied on 'normal' volcanoes: dormant ones si mply do not manifest these phenomena and erupting ones usually do not allow close enough observations. According to the data collected by th e present author over 45 years of investigations, lava lakes are thoug ht to represent the uppermost level of convection currents that stir m olten, gas-rich, magmas. Degassing appears either as powerful jets of high-pressure, high-speed exsolved volatiles escaping through wide-ope n vents or as either quiet exhalation through microscopic pores in the plastic, half molten silicate membrane that covers the surface of the lake when it is calm, or as more or less impressive 'lava fountains'.