New Zealand has experienced about 10 tsunami higher than 5m since Some were caused by distant earthquakes, but most by seafloor earthquakes not far from the coast. How vulnerable is New Zealand to tsunami? New Zealand is quite vulnerable to tsunami. Tsunami hazard for the Pacific basin is higher than for other oceans because of the 'ring-of-fire' - the zone of earthquakes and volcanoes associated with the tectonic plate boundaries around the Pacific. Because tsunami research is relatively new, the knowledge about the severity and frequency of local and distant tsunami is incomplete.
If there is a tsunami warning what should I do? Authorities will give warnings about tsunami if they are coming from far away. Turn on your radio and follow instructions, take essential items if you are told to evacuate, and do not go to the beach to watch the waves.
This is a natural warning; people should move inland away from the shoreline. When you can see the wave you are too close to escape. Tsunami can move faster than a person can run! A: Tsunamis are disasters that can be generated in all of the world's oceans, inland seas, and in any large body of water. Each region of the world appears to have its own cycle of frequency and pattern in generating tsunamis that range in size from small to the large and highly destructive events.
The reason is that the Pacific covers more than one-third of the earth's surface and is surrounded by a series of mountain chains, deep-ocean trenches and island arcs called the "ring of fire" - where most earthquakes occur off the coasts of Kamchatka, Japan, the Kuril Islands, Alaska and South America.
It is in the ring of fire where the main tectonic plates forming the floor of the Pacific collide against themselves or against the continental plates that surround the ocean basin.
Many tsunamis have also been generated in the seas which border the Pacific Ocean. Tsunamis are generated, by shallow earthquakes all around the Pacific, but those from earthquakes in the tropical Pacific tend to be modest in size. While such tsunamis in these areas may be devastating locally, their energy decays rapidly with distance.
Usually, they are not destructive a few hundred kilometers away from their sources. That is not the case with tsunamis generated by great earthquakes in the North Pacific or along the Pacific coast of South America.
On the average of about 6 times per century , a tsunami from one of these regions sweeps across the entire Pacific, is reflected from distant shores, and sets the entire ocean in motion for days. Although not as frequent, destructive tsunamis have been also been generated in the Atlantic and the Indian Oceans, the Mediterranean Sea and even within smaller bodies of water, like the Sea of Marmara, in Turkey.
The U. The States of Hawaii, Alaska, Washington, Oregon, and California are vulnerable to tsunamis triggered by local seismic events as well as teletsunamis generated by distant seismic events along the Ring of Fire. Similarly, seismic events in South America have triggered both local and teletsunamic events.
During the year period from to , tsunamis were observed or recorded in the Pacific Ocean according to the Tsunami Laboratory in Novosibirsk. There are some places where these conditions can produce a truly tsunami-like waves. The Qiantang River in East China is the site of a famous tidal bore, a surge of water that rushes from the river mouth inland. When the tidal conditions are just right, the bore can reach heights of 30 feet and rush inland at speeds of 25 miles per hour. It has become a tourist attraction and some even try to surf it.
Tsunamis are not caused by tidal attraction and it is a misnomer to call one a tidal wave. The majority of tsunamis are caused by earthquakes. Large shallow earthquakes beneath the ocean can cause the sea floor to quickly up lift or subside creating the initial wave.
The larger the earthquake and the more vertical fault motion or slip it produces, the larger the tsunami. It typically takes a magnitude in the mid 7 range to produce a tsunami capable of doing damage and the great ocean-wide tsunamis like Japan, Indian Ocean and Chile have magnitudes in the upper 8 to 9 range.
Most are too small, or too deep and centered under land. In a typical year, about 15 to 20 earthquakes in the magnitude 7 or larger range occur and only one or two of these may produce a tsunami large enough to cause any impacts.
But whenever you feel an earthquake at the coast, it is a natural warning that a tsunami could follow and you should immediately head inland or to higher ground. Much better to be safe than sorry, and practicing your evacuation skills means you will know what to do when a bigger earthquake causes a major tsunami.
Tsunamis last for hours or sometimes days. They always consist of many surges or waves and the first surge is almost never the largest.
Unlike typical wind-caused waves and swells which arrive on the order of every 10 to 20 seconds, tsunami surges are usually many minutes apart and sometimes more than an hour can pass between successive crests. Tsunamis can trick you. They are irregularly spaced in time and just when you might think a tsunami is over, larger surges may arrive. The arrival time of the first surge in a tsunami can be accurately predicted within minutes as it only depends on where the source is located and the distance and sea floor depths to coastal areas.
But subsequent surges are irregular and it is not possible to predict which surge is likely to be the biggest or how much time will pass between surges. In some coastal locations like Crescent City, tsunami energy is trapped in the harbor and can continue for many days. Our recommendation — never return to coastal areas after a tsunami until authorities give you the all clear. In about half of tsunami cases, the initial wave arrival at the coast is a trough, meaning that the water will draw down and appear to retreat, exposing the sea floor over a much larger area that an extremely low tide.
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