The third cause of flood is tsunamis. According to the Forces of Nature website, one cause of tsunamis are high winds. High winds create waves that would hit beaches and shores. According to PAGASA, another cause of tsunamis are seismic activities. Examples are underwater volcanoes and earthquakes. When underwater volcanoes erupt or when earthquakes occur, they form tsunamis. Tsunamis are dangerous because they hit land with high speeds. Furthermore, as they approach the land, it slows down and gains height.