Tsunamis Flashcards
(58 cards)
What is a tsunami?
A series of larger than normal waves, usually caused by volcanic eruptions or underwater earthquakes
Tsunamis are often linked to tectonic events and occur along plate boundaries, especially the Pacific basin’s Ring of Fire.
What are less common causes of tsunamis?
Underwater landslides or meteor/asteroid strikes
These events suddenly displace large amounts of seawater.
How often do smaller tsunamis occur?
Almost every day with little effect
Most small tsunamis go unnoticed.
What causes the formation of tsunami waves?
Energy released during an earthquake causes the sea floor to uplift, displacing the water column above
This displacement forms tsunami waves.
What is the typical height of most tsunami waves?
No higher than 3m
The largest waves can reach heights of up to 30m.
What is the maximum speed of tsunami waves?
Up to 805 km/h
This speed allows tsunamis to travel great distances across oceans.
What makes tsunamis difficult to detect by ships?
Small wave height and long wave length
Tsunamis can be nearly undetectable in deep water.
What is the typical wave length of tsunami waves?
150-250 miles
This long wavelength contributes to their difficulty in detection.
What factors influence the nature of tsunami waves?
Cause of the wave, distance traveled from source, water depth, offshore topography, and coastline orientation
These factors affect energy loss and wave height.
What is the wave period for tsunamis?
10-60 minutes
This is the time between successive waves.
What happens to tsunami waves as they approach shallow water?
Waves slow down and increase in height
This produces onshore waves that can reach up to 30m high.
What determines the depth and destruction of a tsunami upon landfall?
Land uses, population density, warning systems, and physical geography of coastal areas
These factors significantly affect the impact of a tsunami.
How much of the wave energy is scattered back to sea?
Forty percent
This scattering reduces the energy reaching the coast.
How much wave energy is expended at or near the coast?
Sixty percent
This energy loss occurs as the waves approach land.
What is a key characteristic of tsunami events?
A sequence of waves that may last for several hours
The fourth or fifth wave is often the largest.
Fill in the blank: Tsunami waves that are 1m high in the open ocean may reach _______ on land.
30m high
This dramatic increase is due to wave energy concentration.
What can large tsunamis do when they travel inland?
Sweep away buildings, trees, bridges, and people
Large tsunamis can travel several miles inland, causing significant destruction.
What do tsunamis wash away that undermines infrastructure?
Soil
This undermining affects the foundations of buildings, bridges, and roads.
What often happens to small islands hit by tsunamis?
They are often totally destroyed
Small islands have limited resilience against the force of tsunamis.
Can tsunamis be predicted accurately?
No, only early warning signs can be detected
Prediction of tsunamis is currently not possible; only signs of potential tsunamis can be monitored.
What systems are used to detect undersea earthquakes that may cause tsunamis?
Seismic sensors
These sensors are part of a broader monitoring system to provide early warnings.
What does the DART system use to monitor tsunamis?
Seabed sensors and surface buoys
DART stands for Deep-ocean Assessment and Reporting of Tsunamis.
What changes does the DART system monitor?
Changes in sea level and pressure
These changes help in detecting tsunami waves.
How does the DART system communicate tsunami wave information?
Via satellite to tsunami warning stations
This communication is crucial for timely alerts to affected areas.
