Ocean Floor
| Landslide (i.e. Lituya Bay): Rockfalls, icefalls, or underwater landslides and slumps can displace enough water to create a tsunami. Underwater landslides can be caused by earthquakes, tremors, volcanoes, missiles, bombs, or other land movement. Landslides can multiply the effects of a tsunami caused directly by earthquake or volcano, causing subsequent waves and long-term flooding. On December 30, 2002, the daily-erupting Stromboli volcano in Sicily caused a landslide that precipitated a local tsunami. In addition to volcanoes and earthquakes, human earthwork can trigger tsunamigenic landslides, as illustrated by the 1979 collapse of an incomplete runway following constructive rock removal at Nice Airport in France where several humans along 15 miles of the French Riviera were killed by the local landslide tsunami. The 1994 collapse of a railroad dock near Skagway, Alaska created a landslide, which generated a 35-foot tsunami wave that hit the harbor and killed one human. While landslide tsunamis are a growing concern, especially for engineers, the most dramatic damage has been caused by landslides secondary to seismic activity. In Lituya Bay, Alaska, four great tsunamis have been witnessed and recorded by humans in the last 300 years, instantly raising water "run-up" levels more than 1600 feet in Lituya Bay's most unique mountain-enclosed lagoon-like land and sea formation. Seismic landslides greatly contributed to the creation of tsunamis in this bay, though seismic activity was directly involved in half the tsunamis there. The historical occurrence of tsunamigenic meteorites are documented forensically but not attested to by human witnesses. A meteor 1 mile in diameter striking the center of the Atlantic Ocean would flood miles inland along the coasts of Africa, the Americas, and Europe. The wave generated would not crest, but could be very high and cause worldwide water levels to fluctuate for weeks. However, the speed of impact is more important than the size of the meteorite or asteroid: the faster the object is traveling, the higher the wall of water. The trajectory would also be fundamental to modeling the water displacement caused by an extraterrestrial object striking the ocean floor. There is a theory that the Chicxulub meteorite wiped out dinosaurs with a tsunami that washed over the majority of the earth's dry land. |