Volcano InformationSummary Activity Reports Weekly Reports Eruptive History Synonyms & Subfeatures Photograph Maps Data Sources Data CriteriaVolcanoes Eruptions Region InformationRegional Volcanos Regional Highlights Regional Map Regional Sources Regional Links Karthala The Weekly Volcanic Activity Report is a cooperative project between the Smithsonian's Global Volcanism Program and the US Geological Survey's Volcano Hazards Program. Updated by 2300 UTC every Wednesday, notices of volcanic activity posted on these pages are preliminary and subject to change as events are studied in more detail. This is not a comprehensive list of all of Earth's volcanoes erupting during the week, but rather a summary of activity at volcanoes that meet criteria discussed in detail in the "Criteria and Disclaimers" section. Carefully reviewed, detailed reports on various volcanoes are published monthly in the Bulletin of the Global Volcanism Network. Note: Many news agencies do not archive the articles they post on the Internet, and therefore the links to some sources may not be active. To obtain information about the cited articles that are no longer available on the Internet contact the source. -------------------------------------------------------------------------------- KARTHALA Comoro Islands, Indian Ocean 11.75°N, 43.38°E; summit elev. 2,361 m; (All times are local (= UTC + 3 hours) Reports from 2003: | August | September | Reports from 2005: | April | Background. The southernmost and largest of the two shield volcanoes forming Grand Comore Island (also known as Ngazidja), Karthala contains a 3 x 4 km summit caldera generated by repeated collapse. Elongated rift zones extend to the NNW and SE from the summit of the Hawaiian-style shield, which has an asymmetrical profile that is steeper to the S. Historical eruptions have modified the morphology of the compound, irregular summit caldera. More than twenty eruptions have been recorded since the 19th century from both summit and flank vents. Many lava flows have reached the sea on both sides of the island, including during many 19th-century eruptions from the summit caldera and vents on the northern and southern flanks. Map Karthala Information from the Global Volcanism Program -------------------------------------------------------------------------------- 20-26 August 2003 According to news reports, Observatoire Volcanologique du Karthala scientists noted a steady increase in seismicity at Karthala over the past 3 months. Around 100 earthquakes occurred per day in August in comparison to 1-2 per day in June. Sources: Reuters, Agence France-Presse -------------------------------------------------------------------------------- 27 August- 2 September 2003 Reports of a stream of lava flowing from Karthala towards towns on 30 August were false. Authorities stated that only fume was emitted from cracks on the volcano. Source: Agence France-Presse -------------------------------------------------------------------------------- 13-19 April 2005 According to news articles, eruptive activity at Karthala beginning on 17 April consisted of heightened seismicity, and gas and ash emissions. Hundreds of villagers who lived near the volcano evacuated. Flights to the island were cancelled. Scientists found that lava was confined to the bottom of the summit crater. Activity subsided around 19 April, with ash emissions ceasing. On the 19th, residents began to return to their homes and flights to the island resumed. Prior to the activity, scientists at the Mount Karthala Observatory reportedly recorded a "seismic crisis" on 24 March, consisting of 40 small earthquakes in comparison to the normal 15 earthquakes per day. Sources: Agence France-Presse, Reuters, Agence France-Presse