The 3Ps
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\nThe three Ps provide the key to trying to reduce the impact of earthquakes.
\nPrediction involves trying to forecast when an earthquake will happen. Japan tries to monitior earth tremors with a belief that warning
\ncan be given, but this did not happen at Kobe. Foreshocks do occur, but on a timescale useful to evcuation. Experts know where earthquakes are likely to happen, but struggle to establish when. Even looking at the time between earthquakesin a particular area does not seem to work. Similarly, experts struggle to pinoint exactly where along a plate margin they will occur. Animal behaviour has been used in the past
\nProtection invloves building to an appropriate standard and using designs to withstand movement.
\nPreparation involves hospitals, emergency services and inhabitants practising for major diasters, including having drills in public buildings and a code of practice so that people know what to do to reduce the impact and increase their chance of survival.
\nUseful video link below: http:\/\/www.bbc.co.uk\/learningzone\/clips\/preparing-for-earthquakes\/5723.html
\nSome other useful warning signs:
\n\u00b7 Earthquakes are a frequent sign of an impending eruption and their frequency and strength can be recorded
\n\u00b7 Bulging on one side of the volcano – the swelling is obvious and a clear sign of magma moving
\n\u00b7 Tiltmeters can identify small, subtle changes in the landscape
\n\u00b7 Global Positioning Systems (GPS) use satellites to detect movement of as little as 1mm
\n\u00b7 Satellites can detect changes in surface temperature
\n\u00b7 Digital cameras can be used to check for changes in volcanic activity
\n\u00b7 Gases being emitted from the vent change before an eruption
\n\u00b7 Robots called ‘spiders’ are often deployed to look inside the rim of the volcano
\n\u00b7 The past frequency of eruption is often investigated: the gap between eruptions and the pattern of lava flows, ash movement and lahars can tell people about how the
\n volcano is likely to behave<\/p>\n
Monitoring of volcanoes
\nMonitoring gas emissions
\nAs Magma rises into magma chambers gases escape for the depressurising
\nmagma. 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.
\nIn the Mount Pinatubo Volcanic event the amount of Sulphur Dioxide increased by 10 times in 2 weeks. Directly before eruptions the Sulphur Dioxide level can then drop rapidly and scientists think this is due to the sealing of gas passages by hardened magma. This increases pressure in the volcano and leads to explosive eruptions.
\nGround deformation
\nThe movement of magma within the lithosphere 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
\nswelling. Mount St Helens showed this prior to its eruption in 1980.
\nThermal monitoring
\nBoth magma movement, changes in gas release and hydrothermal activity can lead to thermal emissivity changes at the volcano’s surface. We can use satellite imagery, activity of minor extrusive features such as geysers and hot springs and mapping to monitor this.
\nSatellite Images and Remote Sensing
\nRemote sensing is the use of satellites to detect things about the Earth\u2019s surface.This is useful for monitoring any changes in volcanoes at the surface.
\nUsing satellites we can monitor the 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.The satellite can also judge if the ground is being uplifted by measuring the distance between the satellite and the ground.<\/p>\n","protected":false},"excerpt":{"rendered":"