Irazú Volcano | John Seach


Costa Rica

9.97 N, 83.85 W
summit elevation 3432 m

Iraz˙ volcano is located in the Cordillera Central close to the city of Cartago, Costa Rica. It is the highest active volcano in Costa Rica. From the summit it may be possible to see both the Atlantic and Pacific Oceans.

1994 Eruption
A small phreatic eruption occurred at Irazu volcano on 8th December 1994 fumarole on the upper NW-flank. The eruption destroyed forest on the upper slopes of the Rio Sucio, down to 2,500 m elevation, and produced landslides and mudflows.

1963-65 Eruption
An eruption of Irazu volcano began on 13th March 1963 and continued to produce ash for two years. Most ash was deposited in a narrow zone extending 24 km westwards from the summit beyond the city of San Jose. The eruption produced ash, lapilli, blocks, and bombs. No lava flows were produced.

At times ash eruptions occurred at periods of a minute and produced lightning and columns which rose hundreds of metres high. Larger explosions occurred after periods of low activity, and produced columns a kilometer high. In late in 1963, an eruption column rose 8 km above the crater in 4 minutes. Occasionally, landslides of the wall rock into the vent stopped the eruption for up to 2 days.

The climax of the eruption occurred during December 1963 and January 1964, when large volumes of ash and incandescent scoria were erupted and magma rose to within 100 meters of the top of the vent.

Further reading
Alvarado, G.E., Carr, M.J., Turrin, B.D., Swisher, C.C., Schmincke, H. and Hudnut, K.W., 2006. Recent volcanic history of Irazú volcano, Costa Rica: Alternation and mixing of two magma batches, and pervasive mixing. SPECIAL PAPERS-GEOLOGICAL SOCIETY OF AMERICA412, p.259.

Murata, K.J., Dondoli, C. and Sáenz, R., 1966. The 1963–65 eruption of Irazu volcano, Costa Rica (the period of March 1963 to October 1964). Bulletin Volcanologique29(1), p.763.

Irazú Volcano Eruptions

1994, 1963-65, 1939-40, 1933, 1930, 1928, 1924, 1917-21, 1914, 1910, 1909, 1899, 1894, 1889, 1883, 1882?, 1875, 1847, 1844, 1842, 1826?, 1823, 1822, 1821, 1775?, 1726, 1723