Lesson IV: Potential Earthquake Hazards PPT PDF

lesson 4: potential earthquake hazards Presented By; Sam David  Learning Objectives Recognize natural signs of Analyze the identify impending effects of various tsunami different potential earthquake ea...

lesson 4: potential earthquake hazards Presented By; Sam David  Learning Objectives Recognize natural signs of Analyze the identify impending effects of various tsunami different potential earthquake earthquake hazards. hazard  what is an earthquake? An earthquake can be described as the sudden intense  what causes an earthquake? The earth is made up of tectonic plates that constantly move. As the plates move, they cause stresses on the earths crust. The stresses build up when the earths tectonic plates become stuck, creating cracks in the earths surface known as faults. Eventually,  Measuring earthquake s Earthquakes are measured on a scale called the Richter scale (one being the weakest and ten being the strongest). The power of the earthquake is measured using a philippine active faults Image Source: Research gate  Measuring earthquake s Earthquakes are measured on a scale called the Richter scale (one being the weakest and ten being the strongest). The power of the earthquake is measured using a earthquake seismic wave epicentr facts e The focus is the point inside the earths crust where the focus earthquake started. Energy is released from the earthquake in seismic waves. The epicentre is the point on the surface directly above the focus and the energy is hypocenter/Focus Primary source force underneath the ground  epicenter The point parallel to the focus at the surface  driving forces of earthquakes tectonic movement Plates move due to pressure driven by convection  Volcanic Activity Volcanically-caused long period earthquakes are produced by vibrations generated by the  Man-made humans can also induce disturbances earthquakes. Industrial activities such as geothermal energy production, fracking for oil and natural gas, and wastewater disposal can all lead to increased seismic activity that commonly takes  NOtes Only faults with recent displacements are classified as “active” TyPES OF FAULTS left lateral strike-slip fault right lateral strike-slip fault thrust fault compressional stress reverse fault compressional stress normal fault extensional stress blind thrust fault  earthquake hazards related to released Ground shaking  Ground shaking Energy from the Focus/Hypocenter The energy is transmitted in the form of seismic waves. The measurement of earthquake’s intensity depends on the wave’s velocity,  Ground shaking 1.P-waves or compressional waves- are the first wave to cause high frequency vibrations in structures 2.S-waves or shear waves- second to arrive, and vibrates from side-to-side 3.Surface waves (Rayleigh and Love waves)- last to arrive, causes low- frequency vibrations  Ground shaking P-waves and S-waves are moving in the same direction. It’s high frequency vibrations mainly affect low structures. Surface waves are delivering low-frequency vibrations that affect taller structure/s.  Ground shaking P-waves and S-waves are moving in the same direction. It’s high frequency vibrations mainly affect low structures. Surface waves are delivering low-frequency vibrations that affect taller structure/s. Ground rupture  Ground rupture Tension/Cracks Ground moves and the surface of it breaks Common in areas along fault lines. Those areas are called “zones liquefaction  Liquefaction The sediment composition becomes liquified Water-saturated land are only experiencing liquefaction once the ground shakes. It is due to the disturbance on materials causing grains to loosen its  earthquake- induced ground subsidence earthquake-induced ground subsidence Sinking of Ground Can be man-made due to overpumping of groundwater tsunami  earthquake-induced ground subsidence Series of waves in a wave train generated by sudden vertical displacement of column of water. tsu- harbor, nami- wave Local tsunami- heading  earthquake-induced ground Distant tsunami- heading subsidence towards deep ocean. 4 Panels: 1.Initiation 2.Split 3.Amplification 4.Runup Ground shaking near bodies of water unusual sea level (receding shoreline sound of rumbling waves nearby earthquake -induced landslides  earthquake-induced landslides Mass movement of rock, soil, and debris Driven by gravitational force Can be harmful when coupled with earthquakes.