Predicting volcanic eruptions

• A volcano occurs when molten rock, gases and dust are emitted from an opening in the ground called a vent. Volcanoes may occur at constructive and destructive boundaries and also at hotspots.
• Geologists will study the past pattern of volcanic activity in an area.
• The types of materials found on the sides of a volcano help geologist to determine the power and explosive nature of past eruptions.
• The dating of these deposits helps to establish a rhythm- whether the volcano erupts regularly e.g. every 100 years or every 1,000 years.
• Geologist will also study the distribution of material ejected from the volcano. This suggests where ejected material is likely to collect and so helps geologists pinpoint places most likely to be affected by an eruption.
• Geologists have noticed that there is often an increase in the frequency of minor earthquakes prior to an eruption
• Seismographs may be installed around the volcano to monitor the frequency of the small earthquakes before an eruption.
• Tiltmeters may also be installed to identify bulging in the side of the volcano.
• A bulge may indicate that an eruption is likely to occur soon.
• For example, before the eruption of Mount St. Helens in 1980, the side of the volcano bulged swelling by over 100m.
• Scientists will also monitor the quantity and types of gases being emitted from the volcano as these may change prior to an eruption.
• An increase in emissions of sulphur dioxide, radon and carbon dioxide may indicate a possible eruption.
• Geologists will also study the temperature of heat coming out of the crater.
• Local groundwater may become hotter and geysers and hot springs may appear.