Irazu is a stratovolcano located in Costa Rica at an elevation of 3,436 meters within a subduction zone and continental crust setting. According to the Smithsonian Global Volcanism Program, the volcano has a confirmed record of 24 eruptions spanning from its earliest recorded activity around 640 BCE to its latest confirmed eruption on March 3, 1977. The profile's last known eruption year is listed as 1977.
Overview of Recorded Eruptions
The official record documents 24 confirmed eruptions, with the observation methods transitioning over centuries from calibrated radiocarbon isotopic dating for ancient events to direct human-reported observations for later historical periods. The Volcanic Explosivity Index (VEI) values associated with these events reach a maximum recorded level of 3.0. The historical record shows activity distributed across multiple centuries, including the 7th century BCE, the 5th and 7th centuries CE, the 12th century CE, the 16th century CE, three eruptions in the 18th century CE, and eight eruptions in both the 19th and 20th centuries CE.
Selected Historical Eruption Timeline
While the full collection comprises 24 eruptions, representative entries illustrate how documentation and activity have varied over time:
- 640 BCE (approximate): An early confirmed eruption with a start year uncertainty of 500 years, documented via calibrated 14C isotopic evidence at a VEI of 3.0.
- May 1726: A reported observation of activity specifically localized around the Diego de la Haya Crater at a VEI of 2.0.
- September 16 to September 17, 1864: A short-duration confirmed eruption recorded through direct observation at a VEI of 2.0.
- March 13, 1963 to February 13, 1965: A prolonged confirmed eruption sequence spanning nearly two years, reaching a VEI of 3.0 based on reported observations.
- March 3, 1977: A confirmed eruption reaching a VEI of 1.0, marking the latest recorded eruption entry in the official database.
Frequently asked questions
Where is Irazu located and what type of volcano is it?
Irazu is a stratovolcano situated in Costa Rica at an elevation of 3,436 meters.
How many confirmed eruptions has Irazu produced?
The Smithsonian Global Volcanism Program records 24 confirmed eruptions for Irazu.
When did Irazu's earliest recorded eruption take place?
The earliest recorded eruption in the database dates to around 640 BCE, with a 500-year uncertainty range.
When was Irazu's latest recorded eruption?
The latest confirmed eruption in the official record occurred on March 3, 1977, with the profile's last known eruption year listed as 1977.
What is the largest recorded VEI for Irazu?
The highest recorded Volcanic Explosivity Index (VEI) for Irazu is 3.0.
Sources and further context
Official datasets support the event-specific facts.