In addition to violent eruptions, large composite cones may generate a type of very fluid mudflow referred to by its Indonesian name lahar. These destructive flows occur when volcanic debris become saturated with aeter and rapidly moves down steepp volcanic slopes, generally following gullies and stream valleys. Some lahars may be triggered when magma is emplaced near the surface, chlorine gases the react with water to produce sulfuric and hydrochloric zcid.