The 6100 B. P. violent phreatomagmatic eruption of Hule Maar,

ALVARADO INDUNI, G.; SALANI, F. M.

Malargüe, Mendoza

Congreso; 3 International Maar Conference; 2009

IAVCEI

The Hule depression is located in the northern side of the Costa Rica Central Volcanic Range, between Cerro Congo volcano and San Miguel Fault. This depression, which is presently occupied by Hule and Congo lagoons, represents a large maar. It has a subcircular shape and shows a major axis of 2, 25 km and a minor one of 1,75 km embracing an area of 4 km2. The walls range from 110 to 230 m, in height with variable slopes (27º -35°). An intra-maar pyroclastic cone with basaltic lava flow is found within the depression. The volcanic products from the maar explosion are mainly pyroclastic surges, dacitic pumice flows, air fall deposits, ballistic blocks, and reworked deposits that overlie the regional basement and a first level of organic debris. A volcanic sequence is proposed wuth several phases.