Geologic Background:
Volcan San Jose lies at the southern end of a
volcano group that includes the Pleistocene volcanoes of
Marmolejo and Espiritu Santo. The glaciated Marmolejo
stratovolcano is truncated by a 4-km-wide caldera,
breached to the NW, that has been the source of large
debris avalanches. An 8-km-long lava traveled to the SW
from the 1-km-wide summit crater of Espiritu Santo
volcano, which overlaps the southern slope of Marmolejo.
The summit of San Jose is formed by a cluster of six
Holocene craters, pyroclastic cones, and blocky lava
flows.
Historic Activity:
- Erupted 4 times during the 19th century, most
recently in 1895.
- Mild phreatomagmatic eruptions were recorded in the
19th and 20th centuries.
Recent Activity:
- Fumaroles associated with a small andesitic dome
within the central crater. In 1991 a new fumarole field
was discovered on the south flank.
Data Sources:
- Global Volcanism Network (V. 16, No. 5).
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