Painter on the beach at La Perouse Bay. Maui. There are different events caused by volcanic activity that can be very dangerous to life and property. Among them we can name lava flows, lahars ( mudflows ) , ash , debris avalanches and pyroclastic flows . Molten rock or magma being poured on the earth's surface is called: lava. The higher percentage of silicon containing the lava is more viscous . The lava low in silicon can move faster, from 16 to 48 km / h (10-30 mi / h ) , which form lava flows which can be narrow or wide and extending for several meters. Between 1983 and 1993 , flows of basaltic lava that flowed from the volcano Kilauea, on the Big Island of Hawaii , destroyed about two hundred houses and the highway that ran along the south side of the volcano. One of the most significant hazards of eruptions is the ability to burn and bury everything in its path . The lava flows that dams can overflow or break, causing flooding . Some methods to control the advance of the lava flow include: building booms and channels to divert the path of the lava, cooling water supply , or disrupt the advance of the lava with explosives. The volcanoes ( volcanoes ) gases emitted during eruptions . Even when not erupting , cracks in the ground allow gases to escape to the surface. Common volcanic gases are water vapor (90%) , carbon dioxide , hydrogen, sulfur dioxide and hydrogen sulfide. Sulfur dioxide can react with the wind and stay in the atmosphere causing acid rain, which results in deterioration of corrosion and vegetation. Carbon dioxide is heavier than air and tends to accumulate in lethal concentrations can cause asphyxiation animals and people suffer . Large eruptions inject sulfur dioxide into the stratosphere , and when combined with water form sulfuric acid . By sunlight , sulfuric acid particles can lower the temperature of the surface of the earth by several degrees . Also accelerate the destruction of ozone and nitrogen releasing chlorine into the stratosphere .