Debris flows can be triggered by intense rainfall or snowmelt, by dam-break or glacial outburst floods, or by landsliding that may or may not be associated with intense rain or earthquakes. In all cases the chief conditions required for debris flow initiation include the presence of slopes steeper than about 25 degrees, the availability of abundant loose sediment, soil, or weathered rock, and sufficient water to bring this loose material to a state of almost complete saturation (with all the pore space filled). Debris flows can be more frequent following forest and brush fires, as experience in southern California demonstrates. They pose a significant hazard in many steep, mountainous areas, and have received particular attention in Japan, China, Taiwan, USA, Canada, New Zealand, the Philippines, the European Alps, Russia, and Kazakhstan. In Japan a large debris flow or landslide is called "yamatsunami" (山津波), literally "mountain tsunami".