Weegy: Although explosive eruptions occur infrequently at Hawaiian volcanoes, they can be devastating. In about 1790, Kilauea exploded in the deadliest eruption known to have occurred in what is now the United States. [ At least 80 people were killed when a group of Hawaiian warriors and their families was overwhelmed by an extremely fast-moving flow of hot gas and ash (pyroclastic surge) near Kilauea's summit. Thick deposits of volcanic ash on the Island of Hawai`i indicate that much more powerful explosive eruptions have occurred in prehistoric times. Sulfur dioxide gas, continuously emitted during Kilauea's current long-lived eruption, has resulted in persistent volcanic smog ("vog") in downwind areas. Vog, as well as acid rain, forms when sulfur dioxide gas reacts with atmospheric moisture. Vog aggravates respiratory problems, and acid rain damages crops and corrodes metal. On the Island of Hawai`i, the drinking water of many homes with rain-water catchment systems has been contaminated by lead leached by acid rain from roofing and plumbing materials. Earthquakes are another hazard associated with active volcanoes, and the Island of Hawai`i experiences thousands each year. Most of these are too small to feel, but about once a decade a large quake shakes the entire island and causes widespread damage. Before and during an eruption, many small earthquakes occur as molten rock (magma) forces its way through the upper parts of a volcano's interior, and such quakes often provide early warnings of changes in eruptive activity. Deeper within a volcano, stronger earthquakes can be triggered by the stresses exerted by rising magma. ] (More)