Earthquakes and Faults

• Parts of the Earth - inner core, outer core, mantle, and crust
• Focus/Hypocenter - Is the point where the earthquake actually starts. It is the source of earthquake.
• Epicenter - The point where we feel the earth shaking. It is just above the focus or hypocenter.
• Fault - Is a crack or zone of cracks between two blocks of rock.
• Three kinds of faulting - normal faults, reverse faults, and strike-slip faults
• Normal faults - are formed when the hanging wall drops down
• Reverse faults - are formed when the hanging wall moves up
• Strike-slip faults - have walls that move sideways, not up or down. The movement is purely horizontal.
• Two different ways of measuring an earthquake - magnitude and intensity
• Magnitude - the size of an earthquake measured on the Richter Magnitude Scale
• Intensity - how strong the shaking is
• Philippine Institute of Volcanology and Seismology - PHIVOLCS
• I - Scarcely Noticeable
• II - Slightly Felt
• III - Weak
• IV - Moderately strong
• V - Strong
• VI - Very Strong
• VII - Destructive
• VIII - Very destructive
• IX - Devastating
• X - Completely devastating
• Active fault - likely to become the source of another earthquake sometime in the future