seismic hazards

Question 1

what is liquefaction

Answer 1

if an earthquake hits an area of unconsolidated material with a high-water content, the material can behave like a liquid. As a result, structures or objects on the ground can tilt and sink into the ground. Once the shaking stops, the material returns to its solid form.

Question 2

what is an example of an earthquake where liquefaction occured

Answer 2

christ church, new zealand earthquake 2011

Question 3

explain landslides and avalanches as a seismic hazard

Answer 3

steep slopes in mountainous regions are unstable and these can give way during earthquakes (ground shaking and liquefaction can cause slope failure). The problem is made worse if there has been deforestation (removes the binding effect that tree roots have in the soil)

Question 4

what impacts can landslides have

Answer 4

-block rivers which can later flood, damage transport routes, damage dams in upland areas.

Question 5

give an example of an earthquake that triggered landslides and avalanches

Answer 5

The 2015 Nepalese earthquake

Question 6

what is an example earthquake that led to the breaking of a dam by landslides

Answer 6

An earthquake in northern italy in 1963 led to a landslide above the Vaiont reservoir, generating a 1000m wave which drowned nearly 3000 people

Question 7

what is a seich

Answer 7

seiches are like small tsunamis, they occur when an earthquake shakes a lake creating a wave that will usually only be a few feet tall but can still flood or knock over houses, and tip over trees

Question 8

explain the development of a tsunamis wave height and shape

Answer 8

• initially low height (less than 1km) and long wave length (up to 200km)
• when they enter shallow water they slow down and get taller

Question 9

what are five types of seismic hazard

Answer 9

seiches, liquefaction, landslides, avalanches, tsunamis