Lesson 5.2: Earthquake and Earthquake Hazards Flashcards
made up of different plates that constantly move, and this movement gives rise to earthquakes
Earth
the sudden movement of the ground that releases elastic energy in rocks and generates seismic waves
earthquakes
the seismic waves move outward from the ________________ and cause vibrations to the ground
“source”
fractures on the Earth’s crust where rocks on one side of the break move past the rocks on the other side
fault
the spot where the earthquake began
focus
the point on the Earth’s surface located directly above the focus on an earthquake
epicenter
can be anything that includes a physical phenomenon associated with an earthquake that may produce adverse effects on human activities
earthquake hazards
the natural phenomena that might impact an area or a region
hazard
are there regardless of whether there is anyone present to experience them or not
hazard
anything that could potentially be lost when the hazard occurs
risk
measure in terms of units of energy and strength of the shaking
hazard
measured in fatalities or amount of damage
risk
2 classifications of earthquakes
primary and secondary hazards
the direct results of the movement of the ground
primary earthquake hazards
the 4 primary earthquake hazards
- ground shaking
- landslides
- liquefaction
- surface rupture
served as the director of PHILVOCS from 1983 to 2002
Dr. Raymundo Santiago Punongbayan
2 issues of Dr. Punongbayan
June 1990, earthquake
June 1991, Mt. Pinatubo
describes the vibration of the ground when an earthquake occurs, usually recorded in terms of intensity
ground shaking
causes of ground shaking
seismic waves, buildings, bridges, and other structures
occurs if the ground is saturated with water
landslide
includes a wide range of ground movement such as rock fall, rock slide, debris slide, and shallow debris flow
landslide
the magnitude strong enough to trigger rock falls
4.0
the primary reason for all landslides
gravity acting on a steep slope
contributing factors to landslides
- rock and soil slopes
- excess weight from accumulation of rain
- weak slopes
- oversteepened slopes
occurs when sand or soil and groundwater are mixed during the shaking of a moderate or strong earthquake
liquefaction
will force open ground cracks in order to escape to the surface
liquefied soil
happens at the area where the fault zone moves
ground rupture
an offset of the ground surface when fault rupture extends to the surface
surface rupture
a zone with variable width where fractures have developed
deformation zones
the results of primary hazards, which can prove to be more catastrophic
secondary earthquake hazards
4 secondary earthquake hazards
- tsunami
- seiche
- flooding
- fire
refers to a tidal wave, that has little or nothing to do with the tides on the ocean
tsunami
the japanese term for tsunami
“big wave”
2 types of tsunamis
- locally generated tsunamis
- far field tsunamis
caused by earthquakes from nearby trenches
locally generated tsunamis
generated by earthquakes from sources that are located farther from the impact
far field tsunamis
a standing wave in an enclosed or partially enclosed body of water
seiche
apart from incessant rain, this an also be a result of an earthquake
flooding
the result of candles or lanterns that were tipped over because of earthquakes
fire
