Volcanoes

Volcano eruptions are also a cause for earthquakes which result in tsunamis. We will now learn more about Volcanoes.

Here is an informative video: Volcanoes

Basically, volcanoes are formed by the movement of tectonic plates on the surface of the earth. These plates are basically huge pieces of rock that ‘float’ on the mantle (a layer of the earth that is sort-of liquid rock). The tectonic plates are in constant motion, albeit very slow motion. They sometimes move toward each other, other times they’ll move apart, and still other times one will sink while the other rises above it.

When a eruption is about to happen, hot material from below rises and leaks into the crust. Magma, comes either from a melt of subducted crustal material, and which is light and buoyant after melting, or it may come from deeper in the interior of a planet and is light and buoyant because it is very hot.

Magma, rising from lower reaches, gathers in a pool, in a weak portion of the overlying rock called the magma chamber. Eventually, but not always, the magma erupts onto the surface. Strong earthquakes accompany rising magma, and the volcanic cone may swell in appearance, just before an eruption, as illustrated in this picture. White arrows in the picture show the volcano getting bigger as magma rises inside. Scientist often monitor the changing shape of a volcano, especially prior to an eruption. If the volcanoes do not erupt at the top, which means that it erupts from its side, and if the volcanoe is near a sea, the sliding debris that fall into the sea is likely to cause a Tsunami. Underwater eruptions also happen and as i have posted earlier, It will result in Tsunamis and cause much damage

Global Warming

Some may say Global Warming is linked to Tsunamis, some say otherwise. nevertheless i will be touching on it.

Global warming can be split into 2 main groups. Natural and Man-made

Natural:

Natural causes are causes created by nature. It can be caused by the release of methane gas from arctic tundra and wetlands. Methane is a greenhouse gas. A greenhouse gas is a gas that traps heat in the earth's atmosphere. Another natural cause is that the earth goes through a cycle of climate change. This climate change usually lasts about 40,000 years, like the ice ages that happened millenniums ago.

Man-Made:

Man-made causes probably do the most damage. There are many man-made causes. Pollution is one of the biggest man-made problems. Pollution comes in fomrs. Burning fossil fuels for energy is one thing that causes pollution. Fossil fuels are fuels made of organic matter such as coal, or oil. When fossil fuels are burned they give off a green house gas carbon dioxide. Also mining coal and oil allows methane to escape. How does it escape? Methane is naturally in the ground. When coal or oil is mined you have to dig up the earth a little. When you dig up the fossil fuels you dig up the methane as well.

Another major man-made cause of Global Warming is population. More people means more food, and more methods of transportation, right? That means more methane because there will be more burning of fossil fuels, and more agriculture. You may think that agriculture is reducing global warming but think again. think about the amount of pesticides used, think of the smell of the animal waste. The smell contains methane. Cows contribute the most amount of greenhouse gas through their process of letting out gas.Because more food is needed we have to raise food. Animals like cows are a source of food which means more manure and methane. Another problem with the increasing population is transportation. More people means more cars, and more cars means more pollution. Also, many people have more than one car. The more they drive, the more the pollution.

Why Singapore is protected from Tsunamis?

Fault lines in Asia

The above fault line is called the Java Trench. As you can see, Singapore is protected by Indonesia from the left. Indonesia spans from the west part of Malaysia all the way to the west of Indonesia. In the event fault lines moving and a tsunami, Singapore if full protected and will not be affected.

The next nearest fault line will be the Philippines plates. It is located quite a distance away and in the event of an Tsunami, the Philippines and Borneo will absorb some of the impact and most likely Singapore will not be heavily effected.

Tsunami Footages

How a tsunami looks when it comes in

Forces of Tsunamis :

note how the ships, cars and houses are pushed away like paper. Imagine the tremendous amount of forces at play.

Techtonic Principle

Tsunami simulation using second life

Physics behing Tsunami

The principal generation mechanism of a tsunami is the displacement of the volume of water of the sea. This displacement of water is usually attributed to either earthquakes, landslides, volcanic eruptions, or more rarely by meteorites and nuclear tests. The waves formed in this way are then sustained by gravitational force. There is a misconception that tides cause tsunamis, however this is untrue

Tsunamis cause damage by two mechanisms: the smashing force of a wall of water travelling at high velocity, and the destructive power of a large volume of water draining off the land and carrying all with it, even if the wave did not look large, back draft of water.

While everyday waves are about 100 meters wide and 2 meters high, a tsunami in the deep ocean has a spread of about 200 kilometres. Such huge wave travels at well over 800 kilometres per hour(about the speed of jet fighter), but owing to the enormous wavelength the wave oscillation at any given point takes 20 or 30 minutes to complete a cycle and has an amplitude of only about 1 metre. This makes tsunamis difficult to detect over deep water. Ships rarely notice their passage. This is also a problem faced by geologist.

As the tsunami approaches the coast and the waters become shallow, wave are compressed against each other, which slows its speed to below 80 kilometres per hour. However, this causes the waves to get taller each time and the waves grow to enourmous heights.

When the tsunami's wave peak reaches the shore, the resulting temporary rise in sea level is termed run up. Run up is measured in metres above a reference sea level. A large tsunami may feature multiple waves arriving over a period of hours, with significant time between the wave crests. The first wave to reach the shore may not have the highest run up.

How a Tsunami comes about

Tsunami come about when the sea floor deforms and vertically displaces the overlying water. Tectonic earthquakes are a particular kind of earthquake that are associated with the earth's crustal deformation such as moving of the plates at fault line; when these earthquakes occur beneath the sea, the water above the deformed area is displaced from its new position. More specifically, a tsunami can be generated when thrust faults associated with convergent or destructive plate boundaries move abruptly, resulting in huge amount of water displacement, owing to the vertical component of movement involved. Movement on normal faults will also cause displacement of the seabed, but the size of the largest of such events is normally too small to give rise to a significant tsunami. Many countries in the word are near fault lines such as Japan and US. Singapore is lucky that there are not fault lines near it and is protected all round.

Tsunami caused by volcanic eruptions:

There are two different ways that volcanoes can cause Tsunami waves.One of them is that when there is an eruption, huge amounts of ashes and debris and being deposited in the sea. This causes the displacement of water which results in the tsunami.

Tsunamis can also be caused by submarine volcanoes. These underwater volcanoes collapse downwards or spew forth lava heating the surrounding water quickly during eruption. Imagine this as a sort of implosion. A vacuum will be created and the movement of water which result in tsunamis

About the Tsunami

The term tsunami has its origins in the Japanese language(津波); In English it means "seismic sea waves." There is a common misconception between tidal waves and Tsunamis. " Tidal waves," which refer to high waves of water caused by changes in the flow and surge of the ocean. However, Tsunamis can be caused by a few different means: 1) Earthquakes; 2) moving of the ; 3) a submarine volcanic eruption of a certain degree; or potentially, 4) a large meteor impact at sea(might have caused the dinosaurs extinction). Most of tsunamis result from earthquakes.