Waves. Swell, Surf, and Tides

Transcription

1 Waves Swell, Surf, and Tides

2 Tsunamis

3 Tsunamis Waves of Destruction

4 Seismic Sea Waves

5 Seismic Sea Waves Most tsunamis are generated by earthquakes

6 Seismic Sea Waves Most tsunamis are generated by earthquakes However, most earthquakes do not generate tsunamis

7 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

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9 When one side of a fracture moves up or down, seawater is displaced and a wave is generated

10 When one side of a fracture moves up or down, seawater is displaced and a wave is generated

11 Tsunami Characteristics

12 Tsunami Characteristics Wavelengths can be greater than 100 km

13 Tsunami Characteristics Wavelengths can be greater than 100 km Wave speeds can be greater than 700 km/hr

14 Tsunami Characteristics Wavelengths can be greater than 100 km Wave speeds can be greater than 700 km/hr Typical wave periods are minutes

15 Tsunami Characteristics Wavelengths can be greater than 100 km Wave speeds can be greater than 700 km/hr Typical wave periods are minutes Wave heights in the open ocean average 1 m

16 Tsunamis in Deep Water

17 Tsunamis in Deep Water Tsunami waves generally are undetectable by ships in deep water

18 Tsunamis in Deep Water Tsunami waves generally are undetectable by ships in deep water Sea level will rise and lower 1 m in minutes

19 Tsunamis in Shallow Water

20 Tsunamis in Shallow Water Tsunami wave heights can increase significantly in nearshore, shallow water

21 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

22 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

23 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

24 Tsunami Bore

25 Tsunami Runup

26 Tsunami Runup Runup is the height above sea level that a wave reaches as it runs up the coastline

27 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

28 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

29 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

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31 Recent Hawai i Tsunamis

32 Recent Hawai i Tsunamis Historically, a large, deadly tsunami strikes the Hawaiian Islands every 25 years

33 Recent Hawai i Tsunamis Historically, a large, deadly tsunami strikes the Hawaiian Islands every 25 years The last two were in 1946 and 1960

34 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

35 April 1, 1946

36 April 1, 1946 A 7.8 magnitude earthquake in the Aleutian Islands generated a Pacific-wide tsunami

37 April 1, 1946 A 7.8 magnitude earthquake in the Aleutian Islands generated a Pacific-wide tsunami 159 people died in Hawai i

38 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

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40 Travel time in hours

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42 Hilo 1946

43 May 22, 1960

44 May 22, 1960 A 9.5 magnitude earthquake in Chile generated a Pacific-wide tsunami

45 May 22, 1960 A 9.5 magnitude earthquake in Chile generated a Pacific-wide tsunami 61 people died in Hawai i

46 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

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48 Travel time in hours

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50 Hilo 1960

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52 All pau!!!