Term
| What is the disturbing and restoring force of wind waves? |
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Definition
Disturbing force(energy input): Wind wind waves
Landslide/faulting tsunami
Moon/sun gravitation tides
Rapid changes in atmospheric pressure seiche
Restoring force: Gravity |
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Term
| How do water particles move as a wave passes? |
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Definition
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Term
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Definition
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Term
| What defines a deep water wave? |
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Definition
| Depth > L/2…waves do not ‘feel bottom’ |
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Term
| WHat defines a transitional wave? |
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Definition
| L/2 > Depth > L/2…waves feel bottom |
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Term
| What defines a shallow water wave? |
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Definition
| Depth < L/20…waves ‘feel bottom’ strongly…ruled by bottom interaction |
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Term
| What happens to a wave as it approaches the shoreline?( velocity, wave length, wave height, steepness and period) |
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Definition
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Term
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Definition
C= Wavespeed or Celerity
L= Wavelength(m)
T= Time/period(sec) |
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Term
| What happens when a wave breaks? |
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Definition
Become shallow water waves,
‘Feel’ the bottom more and more strongly
Slow down due to bottom friction: Speed… so L (T always constant)
Waves become closer together
Height increases…..Steepen until they Break
Waves crowd together, steepen until unstable
Spills forward because back outruns front
Transfer energy to land (pounding)
Breaks when L/H = 7, wave spills over |
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Term
3 types of surf: Spillers
Where do you find them? |
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Definition
low slope beach
-Waves build more slowly
-Collapses and spills down front
-More gradual energy loss
Constructive- carry sand onto the beach |
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Term
3 types of surf: Plungers
Where do you find them? |
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Definition
medium slope beach
-Waves steepen quickly
-Crest outruns trough
-Curls (good surfing wave!) |
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Term
3 types of surf: Surgers
Where do you find them? |
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Definition
high slope beach
-Wave breaks near beach…not good for surfing
-Sudden energy loss
-Destructive - backwash carries sand off the beach |
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Term
| What are the possible causes of a tsunami? |
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Definition
When water in a lake or sea is displaced by:
- underwater fault movement
- landslide
- volcanic eruption
- large meteorite impacts |
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Term
| What are the warning signs of a tsunami? |
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Definition
| water level drops, smaller waves arrive first |
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Term
| What prevention/ protection measures can be taken to minimize damage of a tsunami? |
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Definition
Build streets perpendicular to coast
Dig trenches and plant vegetation
Preserve coastal dunes, vegetation, coral reefs
Tsunami Warning Systems: Bottom Pressure Recorder (BPR) with transmitter
resolution of about 0.25 mm of water height change |
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Term
| Main feautures of Dec 26 2004 tsunami? |
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Definition
EPICENTER: West of Java
HYPOCENTER: 30 km below sea level
-Magnitude 9.0 Strongest in 40 years,
-85 strong to moderate aftershocks
Burma (or Andaman) Plate – Indian Ocean Plate Boundary |
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Term
| Main features of March 11 2011 tsunami? |
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Definition
EPICENTER: near Tohoku earthquake in northern Honshu, Japan
HYPOCENTER: ~32 km below sea level
-Magnitude 9.0
-Japan experienced over 900 aftershocks since the earthquake |
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Term
| Where do tsunami typically occur? |
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Definition
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Term
| How fast does a tsunami travel? |
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Definition
In open ocean up to 500mph
Near shore 20 mph |
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Term
| How do water particles move as a wave passes? |
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Definition
| They move in circular orbits |
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Term
| What happens to a wave as it approaches the shoreline? |
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Definition
-Wavelength decreases
-Height increases
-Steepens until it breaks
-period is constant |
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Term
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Definition
Refraction is the bending of waves because of varying water depths underneath. The part of a wave in shallow water moves slower than the part of a wave in deeper water. So when the depth under a wave crest varies along the crest, the wave bends.
Focuses energy on headlands- causes erosion |
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Term
| What is wave diffraction? |
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Definition
The apparent bending of waves around small obstacles or the spreading out of waves past small openings
Waves can enter ‘protected harbors’ |
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Term
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Definition
a standing wave in an enclosed or partially enclosed body of water.
Non progressive waves
due to quick atmospheric pressure change |
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Term
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Definition
A huge, unexpected wave that comes out of nowhere. Usually caused by constructive intereferance.
1935 US Rampano- 34 meters or 112 feet high |
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