This little known caldera volcano, located in a sparsely
populated region of SE Chile (46
S, 73
W),
produced a substantial plinian eruption (2-3 km
of andesitic
ejecta) in August 1991 (Global Volcanism Network, 1991; Scasso
et al., 1994). Mudflows, or more precisely joküllhlaups
(volcanic hyperconcentrated flows generated by ice melting), were
formed by eruption-induced runoff that rapidly remobilized the
pyroclastic fall deposit, as occurred during the previous eruption
in 1971 ( Best, 1992). The dispersal of the stratospheric
SO
cloud was traced by TOMS and modeled by an isentropic
trajectory model ( Schoeberl et al., 1993b), providing a test
of knowledge of stratospheric dynamics. If it were not
overshadowed by the magnitude of Pinatubo and the far greater
social problems associated with that eruption, this would have been
a notable event but it has largely passed without much attention.