2. Geological Hazards & Earthquake Preparedness

• GEOLOGICAL HAZARDS - large scale, complex natural events that happen on land.
• TENSION - pulls rocks apart resulting in normal faults.
• COMPRESSION - squeezes rock together resulting in reverse faults
• SHEAR STRESS - causes rocks to slide past each other resulting in strike-slip faults.
• EPICENTER - point of the Earth's surface that is directly above the focus.
• FOCUS - point inside the Earth where the earthquake started.
• FAULT - fracture between two blocks of rock.
• TYPES OF EARTHQUAKE:

  1. TECTONIC QUAKE - due to movement of plates
  2. VOLCANIC QUAKE - due to volcanic activities
  3. COLLAPSE EARTHQUAKE - destruction of structures, caverns, and mines.
  4. EXPLOSION EARTHQUAKE - caused by a nuclear or chemical device.
• GROUND SHAKING - strong vibrations ; its strength depends on factors like the area's physical profile and the features of the fault rupture.
• GROUND RUPTURE - cracks appear on the surface ; weak structures built across a fault have a high chance of being destroyed once movement takes place along the fault.
• LIQUEFACTION - takes place in water-saturated soil and sediments that an earthquake greatly disturbs ; sinks ; may cause house and buildings to subside or tilt.
• GROUND SUBSIDENCE - an earthquake may cause abrupt lowering or sinking of the ground surface.
• Ground Subsidence doesn't have any relation to Liquefaction. TRUE or FALSE?

  FALSE
• MAGNITUDE - refers to the quantity of seismic energy in an earthquake. Measured by a seismograph.
• INTENSITY - rate of the damages observed during an earthquake and can varu as the affected area becomes farther from the epicenter.
• RICHTER SCALE - a scale that measures the strength.
• MODIFIED MERCALLI INTENSITY SCALE - scale used to measure the intensity of an earthquake.
• EARTHQUAKE - sudden rapid shaking of the earth caused by the shifting of underground rock.
• WHAT TO DO BEFORE AN EARTHQUAKE

  1. Understand your risk
  2. Practice drop, cover, and hold
  3. Plan to stay connected
  4. Secure your space
  5. Learn emergency Skills
  6. Gather emergency supplies
• WHAT TO DO DURING AN EARTHQUAKE: drop, cover, and hold
• WHAT TO DO AFTER AN EARTHQUAKE

  1. Stay safe
  2. Stay connected
  3. Check your home for safety
  4. Take care of yourself
• Tsunami Alert Level 1 (Ready)

  • Threat: potential threat
  • Action: be alert for possible evacuation
• Tsunami Alert Level 2 (Watch/Observe)

  • Threat: minor sea level disturbance ; wave heights less than one meter
  • Action: stay away from coast and shoreline
• Tsunami Alert Level 3 (Go!)

  • Threat: life threatening ; wave heights greater than one meter
  • Action: immediately evacuate
• AFTERSHOCKS - smaller earthquakes that always follow the mainshock