Shock Absorber.

I was reading the notes about the measures to adapt and respond to earthquakes and was thinking about the part which they wrote about designing new infrastructure. A question popped up, how do the shock absorbers actually work? How exactly does the shock absorbers actually 'absorb' the tremours?
I found this on Wikipedia:

Structures
Applied to a structure such as a building or bridge it may be part of a seismic retrofit or as part of new, earthquake resistant construction. In this application it allows yet restrains motion and absorbs resonant energy, which can cause excessive motion and eventual structural failure.

After reading this, I don't really get it. What do they mean by 'yet restrain motion and absorb resonant energy'? They also mentioned that it can cause structural failure, that what is the use of it?

To sum up this whole post, it's about the some questions about the shock absorber.

Corinne & Alison.

This is the Wikipedia website: http://en.wikipedia.org/wiki/Shock_absorber

Topographic maps

A map is a way of representing two dimensional surfaces, on the other hand, a topographical map is a way of representing three dimensional surfaces by using contour lines to show the elevation change on the earth's surface.

Contour lines that are placed on the map represent lines of equal elevation. Its kind of like slicing a mountain with a perfectly flat horizontal piece of glass. The intersection of the mountain with the glass is a line of constant elevation on the surface of the mountain and could be put on a map as a contour line for the elevation of the slice.

  Every point on a contour line represents the exact same elevation. As a result of this every contour line must eventually close on itself to form an irregular circle. Contour lines can never cross one another. Each line represents a separate elevation, and you can’t have two different elevations at the same point. The only exception to this rule is if you have an overhanging cliff or cave where, if you drilled a hole straight down from the upper surface, you would intersect the earth’s surface at two elevations at the same X,Y coordinate. 

  Moving from one contour line to another always indicates a change in elevation.On a hill with a consistent slope, there are always four intermediate contours for every index contour. If there are more than four index contours it means that there has been a change of slope and one or more contour line has been duplicated. This is most common when going over the top of a hill or across a valley. Contour lines crossing a stream valley will form a "V" shape pointing in the uphill (and upstream) direction.

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Nile River

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  Can you spot the Nile river in this map? If you have spotted the Nile River, do you spot the White Nile River, the Blue Nile River and the Atbara?
  The Blue Nile and White Niles are the two main rivers that flow from the south into what is referred as the Nile proper. The White Nile is the longer of its tributaries, and the Blue Nile is the source of water and fertile soil. As for the Atbara, it flows into the Nile just north of Khartoum in the Sudan but it contributes less than one percent to total water flow.


The Blue Nile (left), White Nile (right), merge near Khartoum, Sudan


  Now back to the Nile River, its 6695km long, the major cities that are located on the edge of the Nile and White Nile are: Cairo, Gondokoro, Khartoum, Aswan, Thebes, Karnak, and the town of Alexandria lies near the Rozeta branch. 
  After seeing the map, a question popped up my mind. Why does the river flow from south to north? Its because the river just flows down hill, from the high mountains in the middle of Africa to the Nile delta (point where Nile enters the Mediterranean Sea). The picture below will show:



  Millions of people commute on the Nile river everyday. For tourism, luxury cruises and traditional Egyptian sailing boats travel on the Nile river each day. Some of these boats drop tourists off at tourist attractions and is the livelihood of many people.
  As for farming, there are hundreds of farms along the Nile, and usually farmers use boats to transport items such as rice, wheat, cattle, and hay between locations on the Nile.
  Another on which is fishing, for some fishing is a main source of income and wealth.


                                                                 the end^^

Deltas:)

DELTAS:
Deltas are the result of interacting fluvial (river) and, usually, marine systems.  However, they can form anywhere a stream flows into the sea.

The different types of Deltas...
1.  Arcuate (a fan-shaped delta) - e.g., Nile River.  Has many active, short distributaries taking sediment to their mouths.  The receiving (ambient) waters are rather shallow and have relatively even wave action arriving perpendicular to the shore with minimal longshore current.  As the sediment exits the many distributary mouths, the waves push it back, so the coastline is rather smooth.

2. Bird-foot (shaped like a bird foot) delta - e.g., Mississippi River.  Tend to have one or a very few major distributaries near their mouths.  The receiving basin has currents that carry the sediment away as it exits the distributary mouth.  There is a broad, shallow shelf that deepens abruptly, so the trend is to grow long and thin like a bird's toe.

3.  Cuspate (a tooth-shaped) delta - e.g., Tiber River of Italy.  Usually has one distributary emptying into a flat coastline with wave action hitting it head-on.  This tends to push the sediment back on both sides of the mouth, with a "tooth" growing out onto the shelf.

4.  Estuarine delta - e.g., Seine River of France.  This type of delta has a river that empties into a long, narrow estuary that eventually becomes filled with sediment (inside the coastline).

hope this will answer the question that miss jay gave us on monday:D

corinne and alison:D

Volcanoes

  We learnt that a volcano eruption is a release of pressure. Think of a bottle of coke that has been shaken before opening, not only coke come out, but gases comes out as well. Similarly, for a volcano, not only magma is released, different gases are released too. Knowing that volcanoes release gases when it erupts, one of the gases being released is carbon dioxide, a greenhouse gas. However, is the huge amount of such gases released from a single volcanic eruption, more or equivalent to the amount of greenhouse gases caused by human activities? Based on the U.S Geological Survey,the world's volcanoes, both on land and undersea, generate about 200 million tons of carbon dioxide annually, while our automotive and industrial activities cause some 24 billion tons of carbon dioxide every year world wide. From this, we can clearly state that greenhouse gases emissions from volcanoes comprise of less than one percent of those generated by human activities today.

  Volcanoes have different parts. A few of the four main parts are the crater, pipe, vent and the magma chamber. The definitions are all in the notes. A few questions struck my mind though. How is the pipe created? Why does the pipe go up? Why is the pipe narrow? How is the vent created?

  Volcanic hotspots were also mentioned. Hot spots are fixed places within the mantle or oceanic lithosphere, where rocks melt to generate magma.  When a hot spot is situated in the oceanic lithosphere a class of volcanoes known as shield volcanoes is built. The Hawaiian hot spot, for example, has been active at least 70 million years, producing a volcanic chain (o that extends 3,750 miles (6000 km) across the northwest Pacific Ocean. Where a hot spot lies beneath a continental plate the hot spot may generate enormous volumes of lava that accumulate layer upon layer. 


                                                                       ~end~    v(^o^)v

Tsunami

 The recent earthquake and tsunami in Japan has caused a lot of devastation and damage to the country. I’m very sure everyone also knows that Japan is a country that is very prone to Earthquakes. They get it so often that when an earthquake comes, they find it no big deal and would just stay very calm. However, this makes me curious as to why Japan get earthquakes, no matter big or small every year. Is it because of where their position located at? Or is it because they are just unlucky?

  

  Now back to my topic on tsunami, it is reported that “The large earthquake triggered a tsunami warning for countries all around the Pacific ocean.” It really puzzled me how and why an earthquake of such a dangerous magnitude can trigger a tsunami about 10m high. Did these two things just magically happen coincidentally? Or is it because of the impact the earthquake caused resulting in the tsunami? Then again, how are they related?

  It is said on the internet that “The Japanese archipelago is located in an area where several continental and oceanic plates meet. This is the cause of frequent earthquakes and the presence of many volcanoes and hot springs across Japan. If earthquakes occur below or close to the ocean, they may trigger tidal waves (tsunami).”

  Then this answers my question ^-^

   Because of Japan’s location, they get earthquakes very easily. And because the earthquake occurred below or close to the ocean, it triggered a tsunami.

  This picture shows how a tsunami is formed. As one plate slips below another, pressure builds after many years, resulting in a section suddenly giving way. After it gives way, it ruptures the ocean floor, resulting in a massive displacement of water. As the plate snaps back, a force pushes the water up. Oscillation develops underwater at great speed. Sea water is sucked from the shore and rushes back with force. Tsunamis are barely felt on the ocean surface. As the waves reaches the land, the tsunami becomes bigger as the water becomes shallower. 

  As I'm typing this down, another question struck my mind. Why is it that tsunamis are barely felt on the ocean floor? If the pressure that builds up after many years is what determines the impact of the tsunami, then how is more pressure formed? Is it by the number of years the pressure builds thus releasing a greater force?

                                              

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Earthquake

As i've said last week:

Transform Plate Movement A transform plate movement is one where two plates slide laterally past each other. However, movement is not smooth due to friction between the rocks of the two plates. Therefore, sometimes the two plates would get 'stuck' and lock together. But since the convection currents of the underlying magma are still dragging the plates, much tension and pressure is built up at the transform boundary. When there is sufficient buildup of pressure, rocks in the plates break and get jerked apart. This results in earthquakes.

As you may have heard, this afternoon a large quake struck Japan.

7.9 magnitude quake strikes Japan

A 7.9-magnitude earthquake has struck off Japan's northeastern coast, shaking buildings in Tokyo for several minutes and sending people out into the streets.
Japan's meteorological agency warns that a tsunami as high as 20 feet (6 meters) could strike the coast near Miyagi prefecture, closest to the epicenter.
The agency says the quake struck at 2:46 p.m. Friday at a depth of 6 miles (10 kilometers), about 80 miles (125 kilometers) off the eastern coast.
Several quakes had hit the same region in recent days, including a 7.3 magnitude one on Wednesday.

What is the link between GEOGRAPHY and the EARTHQUAKE that just happened?