Medicine Lake Volcano Medicine Lake Volcano Medicine Lake Volcano is a large shield volcano in northeastern California about northeast of Mount Shasta. The volcano is located in a zone of east-west crustal extension east of the main axis of the Cascade Volcanic Arc and the Cascade Range. The thick shield is from east to west and from north to south, and covers more than . The underlying rock has downwarped by under the center of the volcano. The volcano is primarily composed of basalt and basaltic andesite lava flows, and has a caldera at the center. The Medicine Lake shield rises about above
Irazú Volcano produced pyroclastic flows. The latest eruption lasted only 1 day, and occurred on December 8, 1994. It occurred at a flank vent and was a phreatic eruption, which produced lahars. Irazú Volcano The Irazú Volcano () is an active volcano in Costa Rica, situated in the Cordillera Central close to the city of Cartago. The name could come from either the combination of "ara" (point) and "tzu" (thunder) or a corruption of "Iztarú", which was the name of an indigenous village on the flanks of the volcano. In Costa Rica it is known by the name of "El Coloso" (The