Gp. Cortes et J. Raigosa, A SYNTHESIS OF THE RECENT ACTIVITY OF GALERAS-VOLCANO, COLOMBIA - 7 YEARS OF CONTINUOUS SURVEILLANCE, 1989-1995, Journal of volcanology and geothermal research, 77(1-4), 1997, pp. 101-114
The current period of re-activation since 1988 at Galeras volcano, Col
ombia, has been characterized mainly by the following events: (1) a se
mi-continuous series of Vulcanian eruptions during 5-9 May 1989; (2) e
mplacement of an andesitic lava dome at the bottom of the main crater
in October-November 1991; (3) six vulcanian eruptions during 1992-1993
, the first of which destroyed most of the dome on 16 July 1992; and (
4) three volcano-tectonic seismic crises in April 1993, November-Decem
ber 1993 and March 1995. During much of this seven-year period, severa
l small ash and gas emissions also have taken place. The 4-9 May 1989
eruptions originated from the secondary crater Fl Pinta and deposited
ash, lapilli and blocks in the crater area. The 1992-1993 eruptions or
iginated from the main crater and were associated with obstruction of
the conduit by magma from dome emplacement in late 1991, causing overp
ressurization of the system. For the 1992-1993 eruptions, pre-eruptive
seismicity, deformation and SO2 flux all exhibited very low levels. T
he eruptions were characterized by their sudden initiation, low intens
ity (VEI = 1), small eruption columns, and small volumes of erupted ma
terial. The source of the volcano-tectonic seismic crises is located a
pproximately 3 km north and northeast of the crater. Some of these eve
nts were felt in Paste and other towns located around the volcano, on
one occasion causing loss of life, injuries and damage to buildings.