Geologic Background:
Tacana is a composite stratovolcano that
straddles the Mexico-Guatemala border. The volcano rises
1,800 m above deeply dissected plutonic and metamorphic
terrain. The elongated summit region is dominated by a
series of lava domes intruded along a NE trend. A small
adventive lava dome is located in a crater on the upper
SW flank. Viscous lava-flow complexes are found on the
north and south flanks, and lobate lahar deposits fill
many valleys.
Historic Activity:
- Eruptions have occurred in 1855 and 1878.
- Historical activity has been restricted to mild
phreatic eruptions, but more powerful explosive activity,
including the production of pyroclastic flows, has been
documented in prehistorical time.
Recent Activity:
- Increased seismicity began in December 1985. On May
8, 1986 a moderate phreatic explosion opened a 10 meter
wide vent. Seismicity continued through January
1988.
Data Sources:
- Smithsonian's SEAN Bulletin (V. 11, No. 1 and V. 13,
No. 2).
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