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Earthquakes - Coggle Diagram
Earthquakes
Features of Earthquakes
- Fault line: Fracture in the rocks of the Earth's crust. It can range in lengths of a few centimeters to hundreds of kilometers.
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- Focus: This is an underground point where an earthquake originates or begins.
- Seismic wave: This is a vibration generated by an earthquake or explosion within the Earth or along the surface.
- Body Wave: This can be divided into P(Primary) waves and S (Secondary waves). P waves are the fastest type of seismic wave.
- Surface waves: This causes damage to buildings and structures.
- Epicentre: This is the point on the surface of the Earth that is directly above the focus. A seismic wave will be strongest on the surface of the Earth.
7.Aftershocks: These are any lower magnitude earthquakes that follow the main shock of the larger earthquake.
Haiti Earthquake
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Impact of the Earthquake: 2300 confirmed dead. 12,000 people injured.140,000 buildings classified as destroyed or damaged. 30million in US dollars of aid provided to Haiti. Economic loss estimated 1.5billion US dollars. 900 aftershocks were recorded. Strongest aftershock was at 5.8 magnitude.It triggered landslides. The landslide caused 2 deaths and 200 people injured.
Earthquake: This is a sudden shaking of the ground caused by passage of seismic waves through the Earth's crust.
Where do they mostly occur? They mostly occur along fault line, narrow zone where rock masses are displayed by compression and tension.
How an Earthquake occurs: 1. Stress builds up in rock masses. 2 The stress exceeds the strength of the rock 3. This results in sudden fracturing and release of SEISMIC WAVES.
Measuring Earthquakes: 1.Seismograph -This records the motion of the ground during the Earthquake 2. Tsunamimeters are instruments used for the early detection, measurement and real time reporing of tsunami in the ocean. Example: In Japan 2011 experienced a 9.0 magnitude in Tohoku which devastated the Pacific Region with an estimated death rate of 19,300.
Earthquake Scales: Magnitude is an estimate of the energy released by the initial earthquake. Intensity refers to what people felt during the earthquake and how much damage was done.
Richter Scale: It measures the magnitude of an Earthquake. It starts at zero and has no limits. Every time it increases by 1 number it multiples the power of the earthquake by 10.
Moment Magnitude Scale (MMS); This is more accurate. It records the amount of rock movement at the fault line during an earthquake.
Modified Mercalli Scale: This is a scale used to measure the intensity of an Earthquake. This subjective and opinion based.
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