How can earthquakes and volcanic eruptions be predicted and prevented?

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  • Created by: Lina
  • Created on: 12-04-14 20:30

Gas

  • Magma nears the surface of a volcano
  • Pressure decreases
  • Gases escape
  • Sulphur dioxide changes in the amount
  • Indication of an eruption

E.g. The area surrounding Mount Pinatubo was evacuated due to gas monitoring undertaken by the Philippine Institute of Volcanology+ Seismology.

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GPS

  • Pressure from rising magma deforms the volcano, e.g. as at Mount St. Helens in New York State, USA in 1997
  • Ground changes shape: rises up, subsides, tilts, etc
  • GPS uses satellites and radio waves to measure ground deformation
  • A receiver close to the volcano transmits data between satellites orbiting the earth
  • The data is obtained in just a few minutes+ is extremely accurate
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Seismic Activity

  • Before an eruption, magma moves into the area beneath the volcano
  • It collects in a magma chamber
  • The movement of magma produces small earthquakes+ vibrations
  • Seismometer- measures ground vibrations caused by earthquakes+ converts them to radio signals
  • These signals are transmitted to computers that record the earthquakes 24/7
  • Tiltmeters- measure changes in the slope angle/ tilt of the ground

E.g. In Montserrat, 14 seismometers close to the volcano record ground movements

5 electronic tiltmeters record ground movement on the slopes of Soufriere Hills volcano on Montserrat.

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Education

  • Japan
  • 1 September
  • Disaster Prevention Day
  • Emergency drills organised by local governments
  • Consist of ducking under desks to escape falling objects+ evacuating from buildings
  • Schools- first day of school after summer holidays
  • Part of the back-to-school routine
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Building Design

  • Buildings in earthquake zones have earthquake-proof regulations
  • E.g. The San Francisco International Airport
  • Giant Ball Bearings
  • 267 columns support the weight of the airport
  • Each ride on a steel ball bearing 1.5 m in diameter
  • The ball rests in a concave base connected to the ground
  • Earthquake-> the ground can move 50 cm in any direction
  • The columns move a lot less- roll around in their bases-> reduces the movement of the ground
  • Over-> gravity pulls the columns back to the centre of their bases
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Defences 1 against diverting lava flows- detonatin

  • Detonating explosives
  • Disrupt lava flow
  • 1996
  • The Italian Army
  • Detonated 7000 kg of mining explosives
  • To successfully block a lava flow leading from Mount Etna+ threatening villages below
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Defences against diverting lava flows- earth walls

  • Construction of earth walls reflects lava
  • Mount Etna- used earth walls
  • July 2001 eruption
  • On the southern slopes
  • 3 fissures spewed out lava flows
  • Caused damage
  • Threatened to cause much more extensive destruction
  • In the area Rifugio Sapienza
  • And the Etna cable car (tourist facilities, e.g. hotels, restaurants, etc)
  • Earth barriers were erected to limit destruction to a minimum
  • Ditches were dug
  • 2 major lava flows: 26 July+   30-31 July
  • Were confined by the barriers+ artificial ditches
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