Earthquake

-What is Earthquake?
An earthquake (also known as a quake, tremor or temblor) is the result of a sudden release of energy in the Earth's crust that creates seismic waves.
-What are the different types of Earthquake?

• Tectonic Earthquake- These occur when rocks in the earth's crust break due to geological forces created by movement of tectonic plates.
• Volcanic Earthquake- occur in conjunction with volcanic activity.
• Landslips- is a geological phenomenon which includes a wide range of ground movement, such as rockfalls, deep failure of slopes and shallow debris flows, which can occur in offshore, coastal and onshore environments.

-What are the causes of an Earthquake?
Earthquakes are caused by faulting, a sudden lateral or vertical movement of rock along a rupture (break) surface.
-What are the differences between Focus and Epicenter?

• Focus- is the earthquake's underground point of origin or hypocenter (below the center) or refers to the site of an earthquake
• Epicenter is directly above the focus.

-What is Foreshock and Aftershock?

• Foreshock-  is an earthquake that occurs before a larger seismic event (the mainshock) and is related to it in both time and space. The designation of an earthquake as foreshock, mainshock or aftershock is only possible after the event.
• Aftershock- is a smaller earthquake that occurs after a previous large earthquake, in the same area of the main shock. If an aftershock is larger than the main shock, the aftershock is redesignated as the main shock and the original main shock is redesignated as a foreshock. Aftershocks are formed as the crust around the displaced fault plane adjusts to the effects of the main shock.

-What is Seismograph?
Instrument that measure motions of the ground, including those of seismic waves generated by earthquakes, volcanic eruptions, and other seismic sources.
-Differentiate Magnitude from Intensity.

• Magnitude- indicates the amount of energy released at the source (or epicentre) and is measured by the open-ended Richter Scale. 
• Intensity- indicates the violence of earth motion produced there by the earthquake.

-What are the differences of Richter Scale and Rossi-Forel Scale?

• Richter Scale- was developed to assign a single number to quantify the energy released during an earthquake.
• Rossi-Forel Scale- was one of the first seismic scales to reflect earthquake intensities.

PRECAUTIONARY MEASURES to do Before, During, & After an Earthquake.

BEFORE an Earthquake

• Make sure you have a fire extinguisher, first aid kit, a battery-powered radio, a flashlight, and extra batteries at home.
• Learn first aid.
• Learn how to turn off the gas, water, and electricity.
• Make up a plan of where to meet your family after an earthquake.
• Don't leave heavy objects on shelves (they'll fall during a quake).
• Anchor heavy furniture, cupboards, and appliances to the walls or floor.
• Learn the earthquake plan at your school or workplace.

DURING an Earthquake

• Stay calm! If you're indoors, stay inside. If you're outside, stay outside.
• If you're indoors, stand against a wall near the center of the building, stand in a doorway, or crawl under heavy furniture (a desk or table). Stay away from windows and outside doors.
• If you're outdoors, stay in the open away from power lines or anything that might fall. Stay away from buildings (stuff might fall off the building or the building could fall on you).
• Don't use matches, candles, or any flame. Broken gas lines and fire don't mix.
• If you're in a car, stop the car and stay inside the car until the earthquake stops.
• Don't use elevators (they'll probably get stuck anyway).

AFTER an Earthquake

• Check yourself and others for injuries. Provide first aid for anyone who needs it.
• Check water, gas, and electric lines for damage. If any are damaged, shut off the valves. Check for the smell of gas. If you smell it, open all the windows and doors, leave immediately, and report it to the authorities (use someone else's phone).
• Turn on the radio. Don't use the phone unless it's an emergency.
• Stay out of damaged buildings.
• Be careful around broken glass and debris. Wear boots or sturdy shoes to keep from cutting your feet.
• Be careful of chimneys (they may fall on you).
• Stay away from beaches. Tsunamis and seiches sometimes hit after the ground has stopped shaking.
• Stay away from damaged areas.
• If you're at school or work, follow the emergency plan or the instructions of the person in charge.