User:Javid Edwards/sandbox

I WAS ASKED TO DO THIS BY SOME PEOPLE IN FORM 2 IN SVGS THIS WAS A GEOGRAPHY ASSIGNMENT GIVEN TO THEM AND PEOPLE DID NOT KNOW THE ANSWERS SO I AM GIVING YOU THEM YOU ARE WELCOME AND ALSO GIVE JAVID A DOLLAR IF U ARE IN GRAMMER SCHOOL

HOW ACTIVE IS IT?

Over the years there have been a number of activities affecting the earth. The movement of the earth’s plates have resulted In Volcanic eruptions, Earthquakes and Tsunamis. Many lives have been lost and the geographic features of the earth’s surface have been altered significantly. The advancement of technology have allowed us to predict many of these occurrences and helped us to better prepare by choosing where we live or where we build homes and structures that can withstand some of the effects of what we now know as ‘natural disasters’. There are various sites and locations on earth that are noted for earth activities, while others are noted for its peace and tranquillity. This is due to the movement of the earth’s tectonic plates. Countries such as Japan, Hawaii, California, Haiti, and New Zealand are noted for there volcanic eruptions and earthquakes while others such as St. Vincent and the Grenadines, Barbados, St. Lucia are rated for there resilience to earth activity and have fewer instances of earth movement that result in catastrophic damages.

WAYS IN WHICH PEOPLE MONITOR AND PREPARE FOR EARTHQUAKE ACTIVITY

Earthquakes are not as easy to predict as volcanic eruptions. However, there are still some ways of monitoring the chances of an earthquake: •	A seismometer is used to pick up the vibrations in the Earth’s crust. An increase in vibrations may indicate a possible earthquake. Radon Gas escapes from cracks in the Earth’s crust. Levels of radon gas can be monitored – a sudden increase may suggest an earthquake. Many of the prediction techniques used to monitor earthquakes are not 100 percent reliable. Planning and preparing for an earthquake is therefore very important. •	People living in earthquake zones need to know what they should do in the event of a quake. Training people may involve holding earthquake drills and educating people via Television and Radio. •	People may put together emergency kits and store them in their homes. An emergency kit may includes: first-aid items, blankets and tinned food. •	Earthquake-proof buildings have been constructed in many major cities, eg: the Transamerica Pyramid in San Francisco. Buildings such as this are designed to absorb the energy of an earthquake and to withstand the movement of the Earth. Roads and Bridges can also be designed to withstand the power of earthquakes.

TWO LINKS BETWEEN PLATE AND ACTIVENESS The location of particular faults and plate boundaries are heavy determinants in predicting why certain areas are more prone to earthquakes than others. Colliding Plates Where plates come into contact, energy is released. Plates sliding past each other cause friction and heat. Sub ducting Plates melt into the mantle, and diverging plates create new crust material. Subducting plates, where one tectonic plate is being driven under another, are associated with volcanoes and earthquakes. This activity is focused along the edge of the plate boundary where two plates come into contact, forming regions such as the Pacific Ring of Fire, a chain of earthquake and volcanic activity around the edge of the Pacific Ocean – which generates 75% of the world’s volcanoes and 80% of the world’s earthquakes. Divergent boundaries (construction) occur where two plates slide apart from each other. Mid-ocean ridges (eg: Mid-Atlantic Ridge) And active zones of rifting (such as Africa’s East Africa Rift) are both examples of divergent boundaries.

DIFFERENT TYPES OF PLATE BOUNDARIES There are 3 primary types of Tectonic Plates Boundaries: •	Divergent boundaries •	Convergent boundaries •	Transform boundaries DIVERGENT BOUNDARIES As divergent boundaries new crust is created as two or more plates pull away from each other. Oceans are born and grow wider where plates diverge or pull apart. As seen below, when a diverging boundary occurs on land a ‘rift’ or separation will arise and over time that mass of land will break apart into distinct land masses and the surrounding water will fill the space between them.

CONVERGENT BOUNDARIES Here crust is destroyed and recycled back into the interior of the Earth as one plate dives under Another. These are known as Subduction Zones – mountains and volcanoes are often found where plates converge. There are 3 types of convergent boundaries: Oceanic-Continental Convergence; Oceanic-Oceanic Convergence; and Continental-Continental Convergence.

TRANSFORM-FAULT BOUNDARIES

Transform-Fault Boundaries are where two plates are sliding horizontally past one another. These are also known as transform boundaries or more commonly as faults. Most transform faults are found on the ocean floor. They commonly offset active spreading ridges, producing zig-zag plate margins, and are generally defined by shallow earthquakes. A few, however, occur on land. DIFFERENT TYPES OF VOLCANIC ACTIVITY: There are several different types volcanic activities such as: •	Hawaiian eruption •	Strombolian eruption •	Vulcanian eruption •	Plinian eruption •	Lava domes •	Surtseyan eruption

Hawaiian Eruption In a Hawaiian Eruption, fluid basaltic lava is thrown into the air in jets from a vent or line of vents (a fissure) at the summit or on the flank of a volcano. The jets can last for hours or even days, a phenomenon known as fire fountaining.

Strombolian Eruption Strombolian eruuptions are distinct burst of fluid lava (usually basalt of basaltic andesite) for the mouth of a magma-filled summit conduit.

VULCANIAN ERUPTION A Vulcanina eruption is a short, violent, relatively small explosion of viscous magma (usually andesite, dacite, or rhyolite). This type of eruption results from the fragmentation and explosion of a plug of lava in a volcanic conduit, or from the rupture of a lava dome (viscous lava that piles up over a vent).

PLINIAN ERUPTION The largest and most violent of all the types of volcanic eruptions are Plinian eruptions. They are caused by the fragmentation of gassy magma, and are usually associated with very viscous magmas(dacite and rhyolite).

LAVA DOMES Lava Domes form when very viscous, rubbly lava (usually andesite, dacite or rhyolite) is squeezed out of a vent without exploding. The lava piles up into a dome, which may grow by inflating from the inside or by squeezing out lobes of lava (something like toothpaste coming out of a tube). These lava lobes can be short and blobby, long and thin, or even form spikes that rise ens of meters into the air before they fall over.

SURTSEYAN ERUPTION Surtseyan eruptions are kind of hydro magmatic eruption, where magma or lava interacts explosively with water. In most cases, Surtseyan eruptions occur when an undersea volcano has finally grown large enough to break the water’s surface.