Karthala (Union of the Comoros): Recorded Eruptions and Historical Activity

Karthala is a shield volcano located in the Union of the Comoros, reaching an elevation of 2,350 meters above sea level within an intraplate, oceanic crust tectonic setting (under 15 kilometers depth). According to the Smithsonian Global Volcanism Program, Karthala has a documented history comprising 34 confirmed eruptions spanning from the 11th century CE to the 21st century CE.

The official record indicates a maximum recorded Volcanic Explosivity Index (VEI) of 3.0. Out of the 34 confirmed eruptions, 29 have associated VEI observations. The latest confirmed eruption in the database began on January 12, 2007, and ended on January 15, 2007, originating from the Chahalé crater with a VEI of 2.0.

Chronological Distribution of Eruptions

Historical observations of Karthala span multiple centuries, with varying frequencies of recorded activity across different time periods. The confirmed eruptions are distributed chronologically by century as follows:

• 11th Century CE: 1 eruption (earliest recorded starting around 1050 CE, with a start year uncertainty of 150 years).
• 19th Century CE: 18 eruptions.
• 20th Century CE: 11 eruptions.
• 21st Century CE: 4 eruptions.

Notable Historical Activity Examples

Eruptions at Karthala have manifested through various vents, flanks, and craters across the shield structure. Representative records from the official database illustrate the range of documented events:

• 1050 CE: The earliest recorded eruption in the database, documented via reported observations with an estimated start year uncertainty of 150 years.
• July 2, 1850: A confirmed eruption on the west-southwest flank at a 400-meter elevation, noted with a VEI of 0.0.
• July 2, 1876: A confirmed eruption located on the southeast flank (Badjini Massif), recorded with a VEI of 0.0.
• November 24, 2005 – December 8, 2005: An explosive event at the Chahalé crater that reached a VEI of 3.0, representing the largest recorded VEI for this volcano.
• January 12, 2007 – January 15, 2007: The most recent confirmed eruption in the official record, also located at the Chahalé crater, with a VEI of 2.0.