6th grade science Q4

• Crust - this layer is made up of several large and small plates.
• Mantle - it is the thickest layer of the earth and is mostly made up of magma
• Core - divided into liquid layer called outer core and a solid layer called inner core
• An earthquake is the sudden movement or vibration of the crust. It is caused when rock masses shift in new position.
• Earthquakes usually happen along faults.
• Faults are cracks in Earth's crust between two huge plates. The plate on each side of a fault grinds against each other with tremendous force
• The motion of the ground during an earthquake is measured by an instrument called seismograph
• A volcanic earthquake happens with a strong volcanic eruption.
• While tectonic earthquake is caused by the movement of the earths crust.
• Magnitude refers to the amount of energy released by an earthquake from its focus.
• Focus or origin within a fault is the weakest part where the slipage of rocks occurs and where the earthquake originates.
• The area above the focus is called epicenter where strong shaking of the ground is felt.
• In measuring an earthquakes we use the richter scale which was developed by charles f richter, an American seismologist
• Intensity measure how much damage earthquakes cause on the surface or the effects of destruction of

  buildings.