Volcán Maderas is a roughly conical, 1394-m-high stratovolcano that forms the SE end of the dumbbell-shaped Ometepe island in Lake Nicaragua.  The basaltic-to-dacitic volcano is cut by numerous faults and grabens, the largest of which is a NW-SE-oriented graben that cuts the summit and has at least 140 m of vertical displacement.  The small Laguna de Maderas lake occupies the bottom of the 800-m-wide summit crater, which is located at the western side of the central graben.  The SW side of the edifice has been affected by large-scale slumping.  Many pyroclastic cones are situated on the lower NE flank down to the level of Lake Nicaragua.  The latest period of major growth of Maderas took place more than 3000 years ago.  No confirmed historical eruptions are known from the volcano.  A lahar in September 1996 killed six persons in an east-flank village, but associated volcanic activity was not confirmed.