Tsunamis

Question 1

Japan Trench

Answer 1

subduction zone: Pacific Plate subducts move the North American Plate down
= where the elastic strain became so high that the plate could no longer bend.

Honshu earthquake
The wave travels across the Pacific at about the same speed as a jet airplane

Question 2

word tsunami

Answer 2

large harbor waves

Question 3

triggered by…

Answer 3

earthquake
submarine volcanic explosion
underwater landslide
asteroid impact

Question 4

tsunami wave explained

Answer 4

Tsunami waves heights cannot be predicted and the first wave may not be the largest

initiation
split
amplification
run up

deep ocean = fast but small
nearby coast = slow but high

large amount of water is displaced
movement of seafloor
= transferring its energy to the water

Question 5

Indonesia tsunami

Answer 5

2004
earthquake 8.9
slow speed
Following the tsunami an early warming
system was developed for all countries
around the Pacific Rim

Question 6

warning system

Answer 6

tide stations
deep ocean tsunameter
seismograph

communications buoy = receives data from the ocean floor along with readings from surface weather instruments and relays to a satellite
= anchors on sea floor + anchor chain

bottom-pressure recorder = can detect minute changes in water pressure caused by a passing tsunami (batteries and computer)
= sends signal to buoy

BUT FALSE WARNINGS

Question 7

Barbados case study

Answer 7

Over time the Atlantic Plate was pushed under the Caribbean plate, creating a subduction zone which generated a subduction trough or trench right at the junction.

Fine gravel, coarse and fine sands, and clay (clastic sediments) from the South American continent, were deposited in the trough and on the surrounding ocean floor.

At the same time the ocean was full of microorganisms (hard-shelled plankton with shells made of carbonate or silica).

These skeletons were continuously added to the clastics, albeit in small quantities, with the occasional concentrated accumulation.

The rocks which formed on top of the trough were essentially cemeteries of microorganisms, which were soon joined by sedimentary beds rich in algae and plant matter from the South American continent

BIOGENIC ROCKS

Eventually, the plates had moved so much towards each other that the ocean floor started to bend upward.
= tectonic uplift

Barbados Ridge.

Coral rock terraces = fossilized reefs
To grow, corals + associated organisms (algae and sponges) need shallow, clear, well lit, and nutritious water.
The growth of coral was rapid = death was rapid. New reefs grew on top of old ones and formed the terraces.

The reef terraces were much stronger then the Scotland District area rocks (see map of Barbados) and they were therefore better able to withstand physical weathering

Water infiltrating old coral reefs = diluting the calcium = forming caves.
great depths: through continued burial and heating, dead plankton and plant matter was turning into crude oil. The oil began to migrate upward because it is buoyant.