Earthquake

• An earthquake is what happens when two blocks of the earth suddenly slip past one another.
• The surface where they slip is called the fault or fault plane.
• Faults are linear zones of weakness, generally found in plate boundaries and are sources areas of energy to accumulate.
• The location below the earth's surface where the earthquake starts is called the hypocenter, and the location directly above it on the surface of the earth is called the epicenter.
• The scale of the strength used to measure the power of earthquake was made by the American geologist Dr. Charles Richter, and is therefore called the Richter Scale.
• Earthquake magnitude is measured in terms of the amplitude (wave height) of the largest peak traces on a seismograph for a Wood-Anderson seismograph, located 100 km from an earthquake epicenter, in California, where Dr. Richter calibrated his scale to reflect the properties of the rocks of earth's crust.
• Earthquakes are classified into three categories based on their depths: shallow quakes, intermediate quakes, and deep quakes.
• Shallow quakes, usually the most devastating ones, happen within the first 70 km of the crust.
• Intermediate quakes occur within 70- 300 km.
• Deep quakes occur to about 700 Km.
• The land may shift up or sideways due to earthquakes.
• One of the most obvious geological effects of earthquake is the actual ground displacement of the landscape after a large earthquake.
• Landslide occurs when intense vibrations loosen the ground materials on slopes and these materials slide due to gravity.
• Seiches are one of the most benign effects of earthquakes, usually happening great distances from the epicenter.
• Seiches are caused by seismic waves, causing a whole body of water to slosh back and forth.
• Seiches are different from tsunamis as a tsunamis happens through the displacement of the seafloor.