TSUNAMIS Alexandra Norris

Tsunamis

Deep water• Small amplitudes and long wavelengths• Travel at well over 800 km/h

Shallow water• Wave Shoaling will compress and slow the wave to around 80

km/h• Wavelength will decease and amplitude will increase

Seismic tsunamis

Quantification of Tsunamis

• Sieberg (1927) Soloviev-Imamura tsunami intensity scale• Hav is the average coastal height

• Hatori(1986) Tsunami magnitude Mt

• H is amplitude measured by tide gages, and Δ is the shortest path form the earthquake epicentre to the tide station

• Murty and Loomis (1980)• E is energy (ergs)

avHI ln2

1

DbHaM t loglog

19log2 EML

Numerical modeling

• The MOST-3 solves the nonlinear shallow-water wave equations

• η is the wave displacement, d is the undisturbed water depth, u is the horizontal velocities, g is the acceleration due to gravity, R and is the bottom friction term.

0

ht

hu

Ruuu

dghgt

dh

Meteotsunamis

• Tsunami-like waves that are induced by atmospheric processes rather than by seismic sources

• Same periods, same spatial scales, similar physical properties, but Less energetic then seismic tsunamis

• Caused by atmospheric gravity waves, pressure jumps, frontal passages, squalls, etc.

• “rissaga” in Balearic Islands, “marubbio” in Sicily, “milghuba” in Malta, “abiki” in Nagasaki Bay, Japan

Megatsunamis

• Informal name for Tsunamis with extremely large amplitudes• Originate from landslides or impact events

• 1792: Mount Unzen, Japan• 1958: Lituya Bay, Alaska, USA• 1963: Vajont Dam, Italy

• http://www.youtube.com/watch?v=yN6EgMMrhdI

Thank You