U.S. Geological Survey Volcano Hazards Program FAQs:

From the U.S. Geological Survey Volcano Hazards Program FAQs:

"Definitely. Many stratovolcanoes have a plumbing system of hot acid water that progressively breaks down hard rock to soft, clay-rich material. The volcano is gradually weakened, and large parts may suddenly fail. Resulting water-rich landslides are especially dangerous because they can occur without any volcanic or seismic warning.

There are many different kinds of hazards associated with volcanic eruptions, depending on the type of volcano and eruption. Some volcanoes typically produce highly explosive eruptions, such as in the subduction zones of Alaska and the Pacific northwest, and others produce  less energetic eruptions, such as in Hawaii. Therefore, hazards detailed below are not necessarily relevant to every volcano.

U.S. Geological Survey:

U.S. Geological Survey Volcano Hazards Program FAQs:

FEMA National Flood Insurance Program:  

"Flood risk can, and does, change over time. Flood risks change for many reasons: new development, changes in levee classification, and environmental changes, to name a few. As a result FEMA is updating flood hazard maps across the country. These new flood maps, also, known as Digital Flood Insurance Rate Maps (DFIRMs), show flood risk at a property-by-property level.

In the U.S., tsunami early warnings are issued by two warning centers operated by the National Weather Service. The National Tsunami Warning Center (NTWC) monitors for earthquakes and issues tsunami advisories, watches, warnings, and information statements for Alaska, the U.S. mainland, U.S. Atlantic and Gulf of Mexico, Canada, and U.S. interests in the Caribbean (Puerto Rico and the U.S. Virgin Islands)^[1,2,3].

U.S. Tsunami Warning Center FAQs:

"1. Severe ground shaking from local earthquakes may cause tsunamis.

2. As a tsunami approaches shorelines, water may recede from the coast, exposing the ocean floor, reefs and fish.

3. Abnormal ocean activity, a wall of water, and an approaching tsunami create a loud "roaring" sound similar to that of a train or jet aircraft.