Report on Machin (Colombia) — 12 May-18 May 2004
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 12 May-18 May 2004
Managing Editor: Gari Mayberry
Please cite this report as:
Global Volcanism Program, 2004. Report on Machin (Colombia). In: Mayberry, G (ed.), Weekly Volcanic Activity Report, 12 May-18 May 2004. Smithsonian Institution and US Geological Survey.
4.487°N, 75.389°W; summit elev. 2749 m
All times are local (unless otherwise noted)
According to news articles, the Observatory Vulcanológico and Sismológico de Manizales reported that there was an increase in seismicity at Machín in April. About 60 earthquakes were recorded daily, in comparison to the 1-10 earthquakes normally recorded. No surficial changes were seen at the volcano.
Geologic Background. The small Cerro Machín stratovolcano lies at the southern end of the Ruiz-Tolima massif about 20 km WNW of the city of Ibagué. A 3-km-wide caldera is breached to the south and contains three forested dacitic lava domes. Voluminous pyroclastic flows traveled up to 40 km away during eruptions in the mid-to-late Holocene, perhaps associated with formation of the caldera. Late-Holocene eruptions produced dacitic block-and-ash flows that traveled through the breach in the caldera rim to the west and south. The latest known eruption of took place about 800 years ago.