SUMMARYType: caldera |
GEOLOGIC HISTORYA complex volcano with a large central caldera, in northern Iceland. Katla volcano, located near the southern end of Iceland's eastern volcanic zone, is hidden beneath the 200-700-m-thick Myrdalsjokull icecap. The subglacial volcano is one of Iceland's most active and is a frequent producer of damaging jokulhlaups, or glacier-outburst floods, including a catastrophic event in 1755-56. The large 11x14 km caldera has been the source of eruptions originating over a wide area, although most historical eruptions have take place from fissures in the east side of the caldera. These appear to be continuation of the Eldgja fissure system, which extends more than 57 km to the NE towards Grimsvotn and produced voluminous lava flows about 930 AD. Katla has produced frequent subglacial explosive eruptions that have been among the largest tephra-producers in Iceland durin historical time. In spite of the dominating basaltic composition of magma, all eruptions are highly explosive due to the subglacial mode of extrusion. Historic Activity: The last substantial jokulhlaup in this area occurred in 1918, but a small flood in 1955 may have been caused by minor volcanic activity. Recent Activity: Early on July 18, 1999 a small jokulhlaup lasting less than 24 hours, occurred from one of the rivers draing the Myrdalsjokull icecap. Intrusion of magma at a low level within the subglacial Katla volcano or even a small subglacial eruption may have occurred, pssibly associated with a pulse of CO2 which could have caused boiling in geothermal areas under the icecap. Data Sources
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ADDITIONAL INFORMATION
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Last Update: 2/12/00 |