Hazards - Seismic Flashcards
How can scientists predict earthqaukes? (2)
1 - Measure changes in the shape of the earthquake
2 - Monitor tiny earthquakes
What are the primary effects?
Effects that are a direct result of the hazard
What are secondary effects?
Impacts that are caused by primary impacts
What are the social impacts of seismc hazards? (3)
1 - Building damage - homelessness
2 - Rupture gas pipes and break power lines leading to fires
3 - Tsunamis flood large areas - destroy crops, kill people
What are the environmental impacts of seismic hazards? (3)
1 - Damaged power plants leak toxic chemicals
2 - Fires
3 - Water salinised by tsunamis
What are the political impacts of seismic hazards? (3)
1 - Lack of food and water cancause conflict and unrest
2 - Countries development stunted as money put aside to spend on development was spent on repairing damage
3 - Money may need to be borrowed putting causing debt
What are the economic impacts of seismic hazards? (3)
1 - Ground shaking and liquedaction destroy shops
2 - Damage to industry could lead to country relting on expensive imports of goods
3 - Damage expensive to repair
What is liquefaction?
Ground shakes so much that it becomes soft
How can the effecyts of seismic hazards be prevented? (2)
1 - Prevent land that is prone to liquefaction being built on
2 - Build sea walls to prevent tsuamis hitting land
How can the effects of a seismic hazard be prepared against? (4)
1 - Earthquake warning systems via TV, radio
2 - Staying away from buildings, using desk as shelter
3 - Evacuation routes signposted
4 - Search and rescue teams + Fire response units
How can people adapt to mitigate againts seismic risks? (2)
1 - Buidlings designed to sway rather than break by using flexible materials
2 - Tall and strong buildings protect from tsunamis
How many deaths have been attributed to stroms in the last 200 years?
1.9 mil - 10,000 per year
What are the two types of Body waves?
1 - Primary 2 - Secondary
What are the two types of surface waves?
1 - L waves 2 - R waves
Describe the process of an earthquake? (5)
1 - Plates jerk past eachother which builds up pressure
2 - When this pressure is released it sends out shockwaves which are the earthquake
3 - The shockwaves spread out from the focus. The nearer the focus the waves are stronger and cause more damage
4 - The epicentre the earths surface directly above the focus so is where the earthquake is felt first
5 - Eathquakes cause the ground to shake and rupture
What are the three scales which are used to measure an earthquake? (3)
1 - Richter scale - measures the magnitude
2 - Moment magnitude scale (MMS) - Measures energy released by an earthuquake
3 - Mercalli scale - Measures the impacts of an earthquake
Which scale is more accurate, Richter or MMS?
MMS so is more widely used
Descirbe the process of a tsunami? (2)
1 - An underwater earthquake causes the sea bed to move which displaces large volumes of water
2 - The greater the movement of the sea bed the more water displaced and the bigger the wave from the epicentre
What are the features of a tsunami? (2)
1 - Tsuanmis that start near the coast are more powerful because the waves lose less energy as they travel towards land
2 - The waves travel very fast so hit the shore with little warning - high death toll
How are Avalances and Landslides caused? (2)
1 - Shaking of the ground dislodges rock/soil/snow which can cause landslide or avalanches which quickly move downslope
2 - The shaking can lossen ground material which means more water infiltrates. The extra water weight can cause a landslide even after the earthquake has stopped
How does soil liquefaction occur? (2)
1 - When soil is saturated with water the vibrations of an eathquake can cause it to act like fluid
2 - This makes the soil weaker and easier to deform. This makes it more likely to collapse where it has a heavy wight on top of it
How does margin type affect an earthquake? (2)
1 - Earthquakes at destructive plate margins have a higher magnitude than earthquakes at constructive plate margins
2 - This is because the subduction of the plate at a destructive margin causes lots of pressure to build up leading to a huge erathquake when this is released
How does the depth of the focus affect an earthquake? (2)
1 - Deep focus earthquakes have higher magnitudes than shallow focus earthquakes
2 - Deep focus earthquakes however cause less damage that shallow earthquakes because the shock waves have to travel further to reach the surface which reduces their power
Do seismic hazards follow a pattern?
No they are random
How can scientists predict seismic hazards?
They can monitor the movement of tectonic plates to predict which areas are at high risk but can’t predict when the earthquake will strike or it’s magnitude
What are body waves?
Waves that travel through the earth
What are surface waves?
Waves that travel on the earths surface
What are body waves?
Waves that travel through the earth
What are surface waves?
Waves that travel on the earths surface
