Body Waves
Body waves are the first type of seismic waves released during an earthquake. Body waves have little effect on Earth’s surface. There are two types: P-Waves and S-Waves.
P-Waves (Primary or compression waves)
This is the fastest kind of seismic wave. P waves can move through solid rock and fluids. These waves push and pull the rock as it moves through just like sound waves push and pull the air. Usually we only feel the bump and rattle of these waves.
S-waves (secondary waves)
An S wave is slower than a P wave and can only move through solid rock. This wave moves rock up and down, or side-to-side.
Surface waves
There are two types of surface waves: Love waves and Rayleigh waves. Surface waves cause the most damage during an earthquake, even when they are far form the epicenter.
L waves (Love waves or longitudinal waves)
Love waves are a type of surface wave where the ground shifts back and forth. When Love waves pass under a building, they shake the building apart and break it.
Rayleigh waves
Rayleigh waves are smaller than Love waves and are the slowest of the seismic waves. Raleigh waves make the earth roll like waves on the ocean.
Measuring earthquakes
Seismologists, geologists who study earthquakes, use scientific instruments called seismographs to collect information about ground movement before, during and after an earthquake. Scientists cannot accurately predict the exact location of an earthquake but after studying seismic activates, they can use this information to monitor areas where many earthquakes might happen.
Tiltmeter
A tiltmeter is an instrument used by geologist to measure the changing slope of a landscape. Mostly this is used to measure bulges on volcanoes to help monitor conditions and predict eruptions. It can be as simple as a hanging string or a very complex gadget.
Richter scale
In the 1930s, American seismologist Charles F Richter measured the peaks and valleys of a seismogram to determine the strength, or magnitude of an earthquake. From his finding he developed the Richter scale to rate earthquakes. Richter Scales basically measure the amount of energy released from an earthquake. For every increase of one number on the scale, the earthquake is ten times more powerful.
Magnitude Earthquake effects
Micro Less than 2.0 = Micro earthquakes, not felt. About 8,000 per day
Very minor 2.0-2.9 = generally not felt, but recorded. About 1,000 per day
Minor 3.0-3.9 = Often felt, but rarely causes damage. 49,000 per year (est.)
Light 4.0-4.9 = Noticeable shaking of indoor items, rattling noises. Significant damage unlikely. 6,200 per year (est.)
Moderate 5.0-5.9 = Can cause major damage to poorly constructed buildings over small regions. At most slight damage to well-designed buildings. 800 per year
Strong 6.0-6.9 = Can be destructive in areas up to about 100 miles across in populated areas. 120 per year
Major 7.0-7.9 = Can cause serious damage over larger areas. 18 per year
Great 8.0-8.9 = Can cause serious damage in areas several hundred miles across. 1 per year
Rarely, great 9.0-9.9 = Devastating in areas several thousand miles across. 1 per 20 years
Meteoric 10.0+ Never recorded; Unknown
Mercalli scale
Mercalli scales measures the amount of damage that is created by an earthquake.
Modified Mercalli Scale
1 - Detected only by instruments
2 - Slight vibrations, hardly noticed
3 - Slight vibrations, noticed by people not moving
4 - Moderate, felt by people moving about
5 - Quite strong, loose objects fall over
6 - Strong, slight damage to buildings
7 - Very strong, walls crack,
8 - Destructive, chimneys fall
9 - Ruinous, buildings collapse
10 - Disastrous, many buildings destroyed
11 - Very disastrous, few buildings left standing
12 - Catastrophic, total destruction
Seismographs
What a seismograph detects is the movement of ground in the area of the instrument. They are pretty sensitive and can detect, even very slight movements, such as the passing of nearby automobiles, and, man made explosions many miles away. Some of these movements can detect imminent volcanic activity, but, scientists do not, yet, know exactly which of these tremors mean eruptions, and which are, merely, earthquakes. Seismographs are made up of a heavy weight that hangs form a spring or wire. When the ground shakes, the weight appears to joggle and bounces up and down or back and forth. Attached to the other end of the spring or wire is the pen that records the bumping of the weight onto a peeve of paper. This is called a seismogram. When there is no movement the pen draws a straight line while there is high a movement, high and low valleys show on the seismograms.
Other paths of an earthquake
Most of the damage after an earthquake is not from an earthquake itself but from its after effects: tsunamis, fires, and landslides.
Tsunamis
An earthquake under a body of water often lifts or collapses the land under the water. This sudden move of a large body of land displaces the water above it, creating a massive wave. The wave is unlike waves you see at the beach, which are caused by wind. This wave is very long and can travel at hundreds of miles per hour. Once the wave reaches shallow water, the wave is compressed, lifting the water very high, causing a tsunami, or tidal wave. The waves differ depends on the size of the wake or eruption. Tsunamis have millions of tons of force [water] behind them when they strike so there impact is much more powerful. These waves can cost millions of lives in help and also destroy large parts of land that get near it.
Fires
During an earthquake, power lines may be knocked down and natural gas lines sometimes crack, casing fires. Water lines can also get damaged during an earthquake which might also cause flooding. Without water to put out the fires, cities burn to the ground.
Landslides
Landslides are rapid movements of soil, rocks, trees, and plants down a slope. Some landslides are slow moving while others move so rapidly that they can destroy cities and kill people in moments. Areas vulnerable to landslides are areas next to mountains with lots of loose soil and wet climate.
Humans don’t get affected by earthquakes but rather they get directly affected by what is caused after them. Landslides, fires avalanches all affect how humans live economically. Earthquakes also may cause diseases, lack of basic necessities such as water and shelter, loss of life, higher insurance premiums, general property damage, and also road and bridge damages. Animal life is a bit more adaptable to these disasters but habitats can be destroyed costing the life of the animal or forcing them to migrate.
Staying safe
Until we have better ways to predict earthquakes, the smartest thing people can do is be prepared. Most injuries from earthquakes are from falling objects and crumbling buildings and not from the actual movement of the ground.
Before an earthquake
1. Have a battery powered radio, flash light and first aid kids in your house and make sure everyone knows where they are kept.
2. Learn first aid beforehand.
3. Don’t keep heavy objects in high shelves.
4. Fasten heavy appliances to the floor, and anchor heavy furniture to the walls
5. Plan for your family where to meet after an earthquake if anybody is separated.
6. Conduct drills.
7. Find out your office has an emergency plan, know your responsibility at your works during an emergency.
During an earthquake
1. Stay calm if you are indoors; stay out if you are out of buildings. Many injuries occur as people enter or leave the buildings.
2. If you are indoors, stand against a wall near the center of the building, or get under a sturdy table keep some cushion on your head. Stay away from windows and outside doors, if you are in a high rise building stand against a support column.
3. If you are in outdoor stay in an open place. Keep away from over head electric wires and bridges.
After an earthquake
1. Check yourself and nearby people for injuries and provide first aid if possible.
2. Check electric and gas connections if they’re still on because in the future it can cause other disasters such as fires.
3. Turn on your radio or T.V for emergency instructions. Reduce the use of phone lines and only use it if required for conveying some important messages.
3. Stay out of damaged buildings.
4. Wear chapels and gloves to protect against shattered glass and debris.
What science can do
In order for us to live better in the near future we must first deal to what is around us. The most obvious way to reduce injuries, deaths, and property damage would be to stop buildings on or near fault zones. Tall buildings are now reinforced with steel and are flexible enough to allow them to sway a bit so they don’t collapse so easily.
Houses are now concreted with foundations that have wood frames. In earthquake prone areas, many bridges have reinforced columns that help ensure the bridge does not collapse.
Today, earthquake monitoring instruments are installed all over places where there are fault zones and chances of an earthquake. From these instruments, scientists can learn building methods that endure what type of earthquakes that come by.
Along with changing the way buildings are being built, constructing them in proper places is also very important. Solid rock and stable soil are the best locations. Another way to reduce earthquake damage is to connect water, gas, and electric lines with flexible joints to keep pipes from cracking.
The old saying, “An ounce of prevention is worth a pound of cure” is quiet fitting to people who live in near earthquake prone areas.
In conclusion, the worst earthquakes that have occurred are: China, Shansi that had a death rate of 830,000; India, Calcutta that had a death rate of 300,000; and China, Tangshan that had a death rate of 255,000.
There are many questions which to this day we have no answer to. Predicting earthquakes, scientist can do pretty much okay on but still we’ve been unable to accurately predict them.
Perhaps future might tell as only time will tell.
Volcanoes
A volcano is an opening in the Earth's surface or crust, which allows hot molten rock to escape from deep below the surface.To me; volcanoes are like pimples on your face, ready to explode. Though, other than that, volcanoes get formed at a weakness in the crust, usually where crust plates meet and one goes under another one. Like this >
The classic volcanic eruption is a sudden, violent explosion but before that happens, magma or molten rock from deep inside earth pushes upwards and collects underneath the volcano. Once it seeps out, it’s now called lava.
As one of the plates move downward, the rock melts and forms magma. When magma is less dense than the surrounding rock, it rises toward the surface, creating different types of volcanoes over the paths of millions of years.
A powerful eruption may even cause burning hot ash, mixed with dust, gas and mud, to throw several miles in the air.
Here are some of the types of volcanic eruptions:
Hawaiian
Lave that cools in soft, wavy like forms; large amounts of runny lava erupt and produce large low volcanoes
Blocks of thick, sticky lava are followed by burning cloud of ash and gas.
Strombolian
Small, sticky clumps of lava fly out of the volcano.
Vulcanian
Violent explosions shoot out very thick lava bombs
Plinian
Cinders, gas and ash erupt great distances into the air.
Some volcanoes are active, meaning erupting anytime. Some are waiting to erupt and are frozen in the, midst of their mountains. Surprisingly, volcanoes have shaped up many islands, mountains and plains.
What Volcanoes can cause
Volcanic eruptions vary in time and can go on for weeks. Afterwards, what may have looked like a city could look like some pile of ash. Sometimes a layer of ash and dust settle on the land, choking plants and animals nearby, ruining home and blocking roads.
Although volcanic eruptions may be loud and violent, the actual eruption doesn’t kill many people at all. The reason being is that not many people live on top of mountains where eruption might happen and before one could happen, there is usually some warning beforehand. Despite the fact that eruptions themselves have noting to do with environmental loss, it is typically what is caused by it afterwards. Fine ash falling onto a town or village can suffocate people and animals.
Also if a volcano wipes out crops and livestock, the local people may suffer a deadly food crisis.
If there are so many disadvantages, why do people continue to live near volcanoes?
Here are some reasons:
Sea - there tends to be abundant sea life near volcanic islands, so there will be lots of seafood
Fertile soils - The volcanic ash from eruptions is very fertile and good for farming. As volcanic areas are therefore ideal for growing crops, they attract large populations.
Tourism - Volcanoes tend to be awesome with foreigners creating jobs and improving the local economy
Minerals - There are lots of stone deposits from volcanic eruptions, which can be converted into quarries.
Geothermal energy - There will be natural vents near the volcano, in the ground which can be used to provide geothermal energy.
Lack of Choice – sometimes people have no choice whether to live there or not because they have no where also to go.
The parts of a volcano
- Vent
The vent is where the magma flows to erupt on the surface as lava.
b) Crater
This is the opening where lava, ash gas and steam is able to erupt out of.
- Magma chamber
Is where the magma is kept and because of the heat and pressure, magma is pushed upward
- Dike
Smaller side vents.
- Sill
A sill is when magma pushes its way in between open layers.
- Volcanic neck
a volcanic neck is the pipe-like vent of a volcano filled with cooled lava. when the volcano weathers and erodes away, the neck forms intersting landforms.
Active, dormant and extinct
Scientists divide volcanoes into three types: Active, dormant and extinct.
Active volcano
A volcano known to have erupted in recent times, or is likely to erupt. Examples include Mt. St Helens, USA, and Etna, Sicily.
Dormant Volcano
A volcano which is inactive but not extinct. These volcanoes can erupt anytime.
Extinct Volcano
An extinct volcano is a volcano which is not currently erupting and which is not considered likely to erupt in the future.
Volcano shapes
Even though volcanoes emit lava out, they come in many different shapes. The three main volcano shapes are shield, cinder cone, and stratovolcano. Depending on the shape, it is a matter of volume and speed at which the magma is ejected at the earth's surface.
Shield volcano
A shield volcano is formed by non explosive, runny lava flowing over a large area. This results in a gently sloping, domed-shaped mountain form.
Cinder cone volcano
A cinder cone volcano is steep, has loosely arranged sides, and typically has large bowl-shaped craters. These volcanoes are formed by eruptions that throw different sizes of volcanic material high into the air.
Stratovolcano Volcano
These volcanoes are built up from uneven layers of rock and lava. Heavier rocks land near the volcano's opening, while smaller pieces are carried farther away by the wind. Years later, an eruption of lava blankets the rocky material. The resulting shape is a large cone-shaped mountain form.
Hot spots
Hot spot volcanoes are not found on plate boundaries but are found in the middle of the tectonic plates. They’re formed when heat inside Earth escapes towards the outer surface.
For reasons, they are not well understood because heat sometimes melts rocks, which then rises towards the planet's surface. When magma and gases break through the crust, an eruption occurs.
Hotspots are not usually located on the ridges of tectonic plates, but above mantle plumes, where the convection of Earth's mantle creates a column of hot material that rises until it reaches the crust, which tends to be thinner than in other areas of the Earth.
Geothermal energy
Geothermal energy is taken from heated water under the ground. The water is heated because of magma being closer to the surface and underground water close enough to it to take in heat energy. Magma is the very hot liquid rock below the surface that tries to surface. When it does surface, we call this a volcano and the magma now becomes known as lava.
Interesting Answers and Facts.
Earthquakes
Does an airplane in flight feel the effects of an earthquake?
No, unless the airplane is not that high up and something falls on it caused by the earthquake.
No and yes. The earth trembles will not be felt, but any resulting disturbances caused by the earth's movement into the air will be felt by the plane, and there are also air pressure changes that will affect an airplane.
* There are more than 50,000 earthquakes throughout the world every year
* Animals usually can suspect an earthquake before it happens. Catfish are said to be restless before an earthquake, hens have been reported to lay fewer eggs and bees have been seen leaving their hives in a rush.
*The first known instrument to detect earthquakes was noted back in 100 A.D. China.
Volcanoes
* Some people in Turkey hallow out volcanic chimneys and live in there.
* Japanese monkey in winter are known to soak themselves in hot springs to get a chill from the weather.
* It might be surprising that some plants actually live in sea volcanoes. Colorful tube worms change the chemicals in their body that enables them to make the gases that emit out of volcanoes into food.
* According to legend, people used to sacrifice girls in order to please the fire god in stopping a volcano from erupting
* One of the scientific theories in the cause of dinosaur extinction was that a supervolcano erupted killing many of the dinosaur species.
Bibliography
Books
Earthquakes, by Sally M. Walker
BC Science 7, by McGraw – Hill Ryeson
Volcanoes and Earthquakes by Dr. Eldridge M. Moores
Volcanoes by Anna Claybourne
Volcano by Lisa Magloff
Volcanoes and Earthquakes by ken Rubin
Earthquake! By Cynthia Pratt Nicolson
Volcanoes and Earthquakes Susanna Van Rose
Sites
www.bookrags.com/research/volcanic-vent
http://volcano.und.edu/
en.wikipedia.org/wiki/Earthquake
yahoo.com = answers
http://www.vtaide.com/png/George/earthquake.htm
science.nationalgeographic.com
Table of Contents
Earthquakes………………………………………….
Plate boundaries…………………………………….
Faults…………………………………………………
Seismic Waves……………………………………….
Measuring Earthquakes…………………………….
Other paths of an earthquake ……………………..
Staying Safe………………………………………….
What science can do…………………………………
Volcanoes…………………………………………….
What Volcanoes can cause………………………….
The parts of a volcano……………………………....
Active, dormant and extinct……………………......
Volcano shapes……………………………………....
Hot spots and geothermal energy……………….....
Interesting Answers and Facts……………………...
Bibliography…………………………………………..