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Reducing Tectonic Risk

The human race is still not capable of predicting exactly when and where volcanoes and earthquakes will occur. Large scale monitoring of tectonic activity does allow us to narrow down the locations and time frames however, and we monitor volcanoes and earthquakes in many ways. The most widely used method is studying the geographical area of the volcano.

Key words
Management strategies - Techniques of controlling, responding to, or dealing with an event.
Monitoring - Recording physical changes, such as earthquake tremors around a volcano or tracking a tropical storm by satellite, to help forecast when and where a natural hazard might strike.
Planning - Actions taken to enable communities to respond to, and recover from, natural disasters, through measures such as emergency evacuation plans, information management, communications and warning systems.
Prediction - Attempts to forecast when and where a natural hazard will strike, based on current knowledge. This can be done, to some extent for volcanic eruptions and tropical storms, but less reliably for earthquakes.
Protection - Actions taken before a hazard strikes to reduce its impact, such as educating people or improving building design.

Seismic waves
Scientists can use seismic or earthquake waves to show if a volcano is getting ready to erupt. Many volcanoes experience an increasing intensity in frequency and size of earthquakes as they prepare to erupt. We can monitor these using seismometers which produce seismographs.  This technique was used in Nevado Del Ruiz in 1985 and for Mount Pinatubo in 1991.

Pinatubo Seismograph

Monitoring gas emissions
As Magma rises into magma chambers gases escape. One of the main gases is Sulphur Dioxide, and if its quantity in escaping volcanic gas increases this can signal the start of a major eruptive sequence. In the Mount Pinatubo Volcanic event the amount of Sulphur Dioxide increased by 10 times in 2 weeks.
Ground deformation
The movement of magma within the crust can deform the ground above. This has been witnessed at Yellowstone beneath Yellowstone Lake. This swelling of the volcano signals that magma has collected near the surface. Scientists monitoring an active volcano will often measure the tilt of the slope and track changes in the rate of swelling. Mount St Helens showed this prior to its eruption in 1980.
Satellite Images and Remote Sensing
Remote sensing is the use of satellites to detect things about the Earth’s surface. This is useful for monitoring any changes in volcanoes at the surface. Using satellites we can monitor the heat or thermal activity of the volcano to check for upwelling magma, we can check for escaping Sulphur dioxide using gas sensing and we can look to see if the ground is deforming by checking before and after images of the ground.


For earthquakes the equipment above is used plus other equipment and measures, these include;
Using foreshocks by monitoring seismic waves– we often get small earthquakes before “the big one” that can give warnings. The Japan Tsunami (mag 9.0) was preceded by a massive magnitude 7.2 earthquake.

Laser beams - Laser beams can be used to detect plate movement by directing the beam across the fault line.

The best way to protect people from tectonic hazards is to look at the way we construct buildings and roads. Buildings can be designed to withstand the shaking of the earth and to limit the loss of life and damage caused.  The Transamerica pyramid has a shape that can withstand seismic waves and withstood the 1989 Loma Prieta earthquake which struck San Francisco. Other strategies include rolling weights on the roofs of buildings, shatterproof glass to prevent scattering glass during a quake, emergency shutters for glass, gas shut off valves and identification numbers on buildings.

Earthquake proof building

Earthquake proof building

We can also plan for earthquake and volcanic activity.  Prior to events we can plan where we will or will not allow building.  Preventing building on softer sediments can protect people from the worst of the shaking and liquefaction during earthquakes for example.  Plans should also be in place prior to events so that emergency services know what to do during a volcanic or earthquake event

Animal Behaviour
Animal behavior has been suggested as a method, as many observations have shown that animals react to an earthquake before the event and well before human beings.
Tilt meters can show ground deformation, leading to an earthquake. These have been replaced in many cases by more modern and wider ranging satellite imagery.

Watch for the animal behaviour in this clip     NEXT TOPIC - Natural Hazards - Global Atmospheric Circulation



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