Tsunamis! Tsunamis!

TsunamisTsunamis

• Caused by vertical displacement of water• Seismic sea waves • Not tidal waves, not caused by wind• Appear small in the open ocean• Grow in size in shallow water

– Can easily reach 15 m in height • Can travel ~1000 km/hr

Tsunami WavesTsunami Waves

• Long periods (p) and wavelengths (wl)– Wind-waves: p = 10 min, wl = 150 m– Tsumanis: P = 1 hr, wl = 100 km– Waves have a trough and a crest

• Appear small in the open ocean• Grow in size in shallow water

– Can reach >15 m in height • Travel ~1000 km/hr• Can travel around the world quickly

Tsunami Travel Times to Hawaii

Source: After U.S. Geological Survey.

Tsunami Damage in Kodiak, Alaska

Source:Photograph courtesy of National Geophysical Data Center.

TsunamisTsunamis

• Early warning systems• Pacific:

– Established in 1948, 2 years after Hawaii was hit by a tsunami

• Atlantic– Can easily reach 15 m in height

• Indian Ocean– No early warning system until 2005

Source: http://www.prh.noaa.gov/pr/ptwc/bulletins.htm

Indonesia, Dec. 2004Indonesia, Dec. 2004

http://www.globalsecurity.org/military/world/thailand/images/ik_crisp_khao_lak_10.jpg

http://www.globalsecurity.org/military/world/thailand/images/ik_crisp_khao_lak_10.jpg

Source: http://homepage.mac.com/demark/tsunami/

Source: http://homepage.mac.com/demark/tsunami/

Alternative causesAlternative causes

• Oceanic volcanoes– Collapse of part of the volcano

• Landslides– Mass

• Meteorite Impacts – High energy impact from space

Alaska, 1958

Puerto Rico, 1918 Earthquake: 7.5

Source: http://www.usc.edu/dept/tsunamis/caribbean/webpages/index.html

Death toll: 116

Tsunami (40) Aquadilla (32)

Source: http://www.usc.edu/dept/tsunamis/caribbean/webpages/index.html

Source: http://www.usc.edu/dept/tsunamis/caribbean/webpages/index.html