Waves
Swell, Surf, and Tides
Tsunamis
Tsunamis
Waves of Destruction
Seismic Sea Waves
Seismic Sea Waves
Most tsunamis are generated by earthquakes
Seismic Sea Waves
Most tsunamis are generated by earthquakes
However, most earthquakes do not generate
tsunamis
Seismic Sea Waves
Most tsunamis are generated by earthquakes
However, most earthquakes do not generate
tsunamis
Tsunamis are generated when earthquakes fault
the sea floor and displace seawater
When one side of a fracture moves up or down,
seawater is displaced and a wave is generated
When one side of a fracture moves up or down,
seawater is displaced and a wave is generated
Tsunami Characteristics
Tsunami Characteristics
Wavelengths can be greater than 100 km
Tsunami Characteristics
Wavelengths can be greater than 100 km
Wave speeds can be greater than 700 km/hr
Tsunami Characteristics
Wavelengths can be greater than 100 km
Wave speeds can be greater than 700 km/hr
Typical wave periods are 12-15 minutes
Tsunami Characteristics
Wavelengths can be greater than 100 km
Wave speeds can be greater than 700 km/hr
Typical wave periods are 12-15 minutes
Wave heights in the open ocean average 1 m
Tsunamis in Deep Water
Tsunamis in Deep Water
Tsunami waves generally are undetectable by
ships in deep water
Tsunamis in Deep Water
Tsunami waves generally are undetectable by
ships in deep water
Sea level will rise and lower 1 m in 12-15 minutes
Tsunamis in Shallow Water
Tsunamis in Shallow Water
Tsunami wave heights can increase significantly in
nearshore, shallow water
Tsunamis in Shallow Water
Tsunami wave heights can increase significantly in
nearshore, shallow water
However, most tsunamis wave do not break like
normal wind waves
Tsunamis in Shallow Water
Tsunami wave heights can increase significantly in
nearshore, shallow water
However, most tsunamis wave do not break like
normal wind waves
Tsunami wave crests can out run the troughs and
form a wall of water separating different sea levels
Tsunamis in Shallow Water
Tsunami wave heights can increase significantly in
nearshore, shallow water
However, most tsunamis wave do not break like
normal wind waves
Tsunami wave crests can out run the troughs and
form a wall of water separating different sea levels
The wall of water is called a tsunami bore
Tsunami Bore
Tsunami Runup
Tsunami Runup
Runup is the height above sea level that a wave
reaches as it runs up the coastline
Tsunami Runup
Runup is the height above sea level that a wave
reaches as it runs up the coastline
Tsunami waves slow in shallow water but often
strike a coastline at speeds greater than 50 mph
Tsunami Runup
Runup is the height above sea level that a wave
reaches as it runs up the coastline
Tsunami waves slow in shallow water but often
strike a coastline at speeds greater than 50 mph
Along flat coastlines, tsunamis waves can travel
inland for several miles
Tsunami Runup
Runup is the height above sea level that a wave
reaches as it runs up the coastline
Tsunami waves slow in shallow water but often
strike a coastline at speeds greater than 50 mph
Along flat coastlines, tsunamis waves can travel
inland for several miles
When a wave retreats, it drags debris and humans
into the ocean
Recent Hawai’i Tsunamis
Recent Hawai’i Tsunamis
Historically, a large, deadly tsunami strikes the
Hawaiian Islands every 25 years
Recent Hawai’i Tsunamis
Historically, a large, deadly tsunami strikes the
Hawaiian Islands every 25 years
The last two were in 1946 and 1960
Recent Hawai’i Tsunamis
Historically, a large, deadly tsunami strikes the
Hawaiian Islands every 25 years
The last two were in 1946 and 1960
Hawai’i is overdue statistically for a large,
destructive tsunami
April 1, 1946
April 1, 1946
A 7.8 magnitude earthquake in the Aleutian Islands
generated a Pacific-wide tsunami
April 1, 1946
A 7.8 magnitude earthquake in the Aleutian Islands
generated a Pacific-wide tsunami
159 people died in Hawai’i
April 1, 1946
A 7.8 magnitude earthquake in the Aleutian Islands
generated a Pacific-wide tsunami
159 people died in Hawai’i
The runup was 12.0 m in Pololu Valley
Travel time
in hours
Hilo 1946
May 22, 1960
May 22, 1960
A 9.5 magnitude earthquake in Chile generated a
Pacific-wide tsunami
May 22, 1960
A 9.5 magnitude earthquake in Chile generated a
Pacific-wide tsunami
61 people died in Hawai’i
May 22, 1960
A 9.5 magnitude earthquake in Chile generated a
Pacific-wide tsunami
61 people died in Hawai’i
The runup in Hilo Bay was 10.7 m
Travel time
in hours
Hilo
1960
All pau!!!