Tuesday, January 12, 2016

Shaky foundations


Here we are in a new year, at least according to the Roman Calendar, for other like the Chinese one the new year is still to come, as well as for the Hebrews and other. In anyway, now that the big fiesta has come and gone, we can come back and focus again into blogging.

After the series Jojo vs Earthquake in which I went deeper into the Earth to lay down the foundation of the Earthquake phenomenon, I will now come back to the surface of our planet, where we live, and begin to look into the Earthquakes itself, their impacts and consequences, and how we, humans, we can mitigate those consequences.

First things first, when it comes to earthquakes, what is the map of the main tectonic plates of the planet?


As you can see, this planet is quite a jigsaw puzzle, and we live on that jigsaw puzzle for the best or the worst.Some plates are huge compare to others, but they all move due to underground movement mainly in the Mantle. That movement makes those different plates collide with each other smoothly or brutally, it is that plate motion which leads to earthquakes.

The Philippines themselves are more specifically located in the West-Pacific Ocean Basin. Geographically the Philippines are situated on what is generally known as the Pacific Ring of Fire - the most seismically active region of the planet. 



Invisible to our eyes, the country is crossed by many faultlines, the focal point of earthquakes. The two biggest faultlines are the Trenches laying under the sea. One Trench is located on the West side of Luzon (Manila Trench), the other Trench is located on the East side of the Visayas and Mindanao (Philippine Trench). Smaller Trenches exist as well like the Cotabato Trench, Negros Trench and Sulu Trench (all located on the West of Mindanao under sea)

As a matter of fact, although the Philippines are seen as one country, geologically speaking it is a divided country - Luzon is part of the Philippines Plate, where the Visayas and Mindanao are part of the Eurasian Plate. It has real implication when you understand that being on two different plates, that also mean that they entirely depend on the motion of each of those plates. 



As far as we know the general motion of the Philippine Plate and the Eurasian Plate is a move in opposite direction on a collision course. The Philippine Plate moves in a Westward direction, where the Eurasian Plate moves in a Eastward direction. This Tectonic collision is what is at the basis of the Earthquakes in the Philippines.




That Tectonic motion is unstoppable and unavoidable, we have to live with it. Filipinos, and all of those who, like me, choose to live here live really on shaky foundations indeed. But hey, is it not true that it is more fun in the Philippines?

Mabuhay!


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Tuesday, January 5, 2016

Jojo vs Earthquakes (Part 5)


We arrived at the end, - nearly, - of our journey through Earth's Layers.

Here in the depth of our planet lies the Core, although we should say Cores plural. The Core is viewed as a two distinct part region, both making the Core of the Earth, but in two different states - one liquid (Outer Core), one solid (Inner Core). It happen that, according to last research there could even be an inner inner core. Whatever way you look at it, it is extremely hot. The hottest part of the Core is at a nice 6000°C (10,800°F), or to put it differently, it is as hot as the surface temperature of our Sun. Not bad for a small planet...

Both layer are composed of the same alloy - Nickel-Iron. It is the pressure which dictates the state of the alloy. In the case of the Outer Layer, the nickel-iron alloy is in liquid form (10 times the viscosity of liquid metal on the surface of the Earth). In the case of the Inner Core, the nickel-iron alloy is in solid form because the pressure is so high that it prevents the alloy to become liquid.


THE OUTER CORE
When we quit the Mantle layer, we meet the Outer Core 2,890Km (1,800 Miles) beneath our feet. 
As mentioned above, the Outer Core is made up of a liquid nickel-iron alloy. It's temperature ranges from 4,030°C (7,280°F) at the Mantle-Core Boundary to 5,730°C (10,340°F) at the Outer-Inner Core Boundary. It's thickness is around 2,300Km (1,400 Miles).

THE INNER CORE
Continuing our travel through the Core, we finally reach the Inner Core 5,150Km (3,200 Miles) beneath Earth's Surface, it is the deepest layer of our planet. As solid ball of nickel-iron, it is massive sphere of 70% the Moon's Radius in size (around 1220Km radius or around 760 Miles). 
It is here that we find the highest temperatures (around 6000°C) and the highest pressure (between 330 and 360 Gigapascal - or in lay man's term between 3,3 millions and 3,6 millions the atmospheric pressure)


Since they are so deep in our planet we could think that it is not so important on our human level. After all don't we live way above the Core, on the Crust? 

But if you remember what I said in Jojo vs Earthquake (Part 2), the Earthquakes are born from the movement of the Crust, and that global Crust movement is a result of Convection Current formed deep into our planet due to heat transfer through Earth's Layers. So the heat below our feet is quite effective on us at the surface as a collateral (and sometimes deadly) effect.

Besides, the Core, and the interaction between the Inner and Outer layer of the Core is vital to us as it is the place where our Magnetic Shield is formed. 

Without the Magnetic Field created by the Core of our planet you can say goodbye to all life on this planet, yours included. 

Although it is not Earthquake related, I will come to that on a next post when addressing another kind of Natural Disaster we should prepare for.



At least, now, we know a little bit more about what's beneath our feet. With that knowledge, although basic, we can visualize and better understand the Earthquakes phenomenon, as well as the Volcanoes phenomenon. So, in the next posts we will quit the Inner Core and come back to the Surface and look at things on a human scale.

Until then, thank you for reading.
Mabuhay!

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