BD Tsunamis. Inventaire historique des tsunamis en France. Année ...
TSUNAMIS Alexandra Norris. Tsunamis Deep water Small amplitudes and long wavelengths Travel at well...
Transcript of TSUNAMIS Alexandra Norris. Tsunamis Deep water Small amplitudes and long wavelengths Travel at well...
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