Science 6

• An Earthquake is a weak to violent shaking of the ground caused by the sudden movement of rocks below the surface of Earth.
• Earth’s surface is composed of a solid material called the crust.
• The crust is made up of TECTONIC PLATES.
• There are about 20 plates along the surface of Earth that move continously and slowly.
• The movement of tectonic plates are caused by the mantle.
• The mantle is the layer underneath the crust.
• The crust together with the upper mantle form lithosphere.
• Earthquakes usually originate from a tectonic plate boundary.
• Faults are lines or cracks in Earth’s surface that are caused by the movement of tectonic plates.
• Focus is the point below the surface of Earth where the trembling started.
• Focus is also known as Hypocenter.
• The place above the focus is the epicenter.
• The epicenter is where the earthquake is strongest on the surface.
• There are three types of earthquake.

  Volcanic Earthquake

  Tectonic Earthquake

  Collapse Earthquake

  Explosion Earthquake
• The most common type of earthquake is Tectonic Earthquake.
• Volcanic Earthquakes are caused by volcanic activities such as rising of magma or lava beneath active volcanoes.
• Collapse earthquake are small quakes that occur in caverns or mines.
• Explosion earthquakes result from the explosion of a nuclear or chemical material or device.
• The plates under the ocean are called oceanic plates.
• Stress is the force applied to a rock and may cause deformation.
• Seismology is the study of seismic waves
• The scientists who specialize on this discipline are called seismologist
• Seismologist use an instrument called seismograph to detect and record earthquakes.
• A seismogram is the recording of the ground shaking at the specific location of the instrument
• Primary waves are the fastest seismic waves and can move through any phase of matter.
• Secondary waves can only move through solids.
• Those waves that are the most destructive are the surface waves which generally have the strongest vibration.
• Surface waves are the last to reach the seismograph and occur the longest.
• The magnitude refers to the size of the seismic waves that are recorded in the seismograph
• The Richter scale measures the intensity or magnitude of an earthquake
• The larger the magnitude the stronger the Earthquake is
• The intensity is the strength of the earthquake based on its ob effects on humans and animals
• The intensity is represented by Roman numerals
• The intensity of an earthquake is generally near the epicenter
• An earthquake is usually followed by aftershocks
• Aftershocks is within one or two lengths from the main shock fault