Topic 4: Potential Earthquake Hazard

• Earthquake - is a weak to violent shaking of the ground produced by

  the sudden movement of rock materials below the earth’s surface. It is a wave-like movement of the earth’s

  surface and may classified as tectonic or volcanic.
• tremor : temblor
• Volcanic Earthquakes: are produced by movement of magma beneath volcanoes.
• Tectonic earthquakes: are produced by sudden movement along faults and plate boundaries.
• Focus - actual location beneath the surface where the earthquake begins.
• epicenter - point on the earth’s surface located directly above the focus of an earthquake. 
• fault - refers to a fracture, fissure, or a zone of weakness where movement has occurred. 
• magnitude - energy released at the source of the earthquake and determined by seismographs.
• intensity -strength of shaking produced by the earthquake at a certain location.
• seismograph -instrument that records an earthquake
• seismometer -sensor that detects ground motion.
• seismogram - record of earthquake retrieved from a seismograph.
• aftershock -usually weaker earthquakes that follow the main shock of an earthquake’s sequence
• ground shaking - disruptive up-down and sideways movement or motion experienced
• ground rupture - displacement on the ground due to the movement of fault
• liquefication -mixing of sand or soil and water underground during the shaking of a moderate or strong earthquake
• tsunami -sea waves resulting from the disturbance of ocean floor by an earthquake.
• earthquake induced landslide - failures in steep or hilly slopes triggered by an earthquake
• earthquake induced ground subsidence - a gradual setting or sudden sinking of the earth's surface
• tsunami - sea waves resulting from the disturbance of ocean floor by an earthquake
• earthquake induced lanslide - failures in steep or hilly slopes triggered by an earthquake
• earthquake induced ground subsidence -a gradual settling or sudden sinking of the earth’s surface
• tsunamis can be detected using our human senses
• recognize a tsunami's natural signs through:

  feel

  hear

  see

  run
• two kinds of tsunami: local tsunami & far field or distant tsunamis
• storm surges -are wind generated waves on the surfaces of the sea
• local tsunami - confined to coasts within a hundred kilometers of the source usually landslide or a pyroclastic flow.It can reach the shoreline within 2-5 minutes
• far field or distant tsunamis -can travel from 1 to 24 hours before reaching the coast of the nearby Countries. These tsunamis mainly coming from the countries bordering Pacific Ocean like Alaska in USA and

  Japan (2011).