Research Investigation – Can Volcanic Eruptions be predicted?
Earth has many hazards, some of the most dangerous being those occurring naturally. Volcanoes are a leading example of the many ways that Earth can be life threatening without human assistance, but how dangerous are they really?
A volcano is essentially a vent in the earth’s surface, allowing magma, or lava, to flow free. It is made up of many different vents and pipes, as well as sill, ash, magma and lava. The diagram to the right demonstrates some of the different components a volcano has. A Volcano also releases gases and, more importantly, volcanic ash, which can also be hazardous.
Knowing that both the lava and ash from a volcano are dangerous to society asks the question, can we predict when one will erupt?
How do volcanoes erupt?
Each year, an average of 50 to 60 volcanoes erupt (almost one a week). Three of the main causes leading to volcanic eruption are gas pressure, lightness of the magma and the amount of magma in a chamber.
The density of the magma is less than that of the surrounding rock, allowing it to rise upwards. Different factors change the likelihood of eruption due to this, but if ‘the density of the magma between the zone of its generation and the surface is less than that of the surrounding and overlying rocks, the magma reaches the surface and erupts.’ (Scientific American, 1999). The gas pressure exists in the magma, and when more water begins to esxolve from the magma the higher it rises, there is a larger ratio of gas to magma. This can cause an eruption when the amount of gas reaches a high percentage. The last cause of eruption is the amount of magma in a chamber. This idea is simple; when more rock is melted into magma, the magma is pushed upwards, until it overflows, (Scientific American, 1999).
Where do volcanoes form?
USGS, n.d, states that ‘There are about 1,500 potentially active volcanoes worldwide, aside from the continuous belt of volcanoes on the ocean floor. About 500 of these have erupted in historical time.’ Volcanoes occur either at tectonic plate boundaries or at hotspots. Tectonic plate volcanoes occur when the plates either diverge or converge. Diverging boundaries allow magma from the mantle to rise up forming a volcano, whilst converging boundaries form volcanoes through subduction. When one plate moves under the other, volcanoes and earthquakes are likely to form there. Hotspots do not have to occur at plate boundaries. They happen at weak spots in the earth’s crust when the heat from the magma melts and rises through the surface. This can form island chains as the plates move over the hotspot. Figure 2 shows this process.
Can volcanic eruptions be predicted?
Before a volcano is going to blow, there are warning signs. Live Science identifies some of these warnings as, ‘small earthquakes beneath the volcano, slight inflation, or swelling, of the volcano and increased emission of heat and gas from vents on the volcano,’ (Melina, 2010). These warnings can occur from as a week to as long as months before. In terms of predicting exactly when a volcano will erupt, the answer is no. Just like when predicting the weather, monitoring patterns and events as well as reading signs from data can give an estimate to when an eruption might occur, or a time frame in which the eruption could occur, but not the exact date.
A way that scientists predict the likelihood of an eruption is through the use of satellites and GPS. These systems are used to measure the inflation of the volcano as the gases and magma expand. Another device used to measure the movement of volcanoes is with seismographs which measure movement in the earth’s crust. Sciencing, 2017 states that this is important as ‘A violent seismic reading is often a precursor to an eruption when it occurs near a volcano,’ (Wilson, 2017).
Another effective way at determining the chance of a volcanic eruption is through the monitoring of gas emissions. When magma rises to the surface of a volcano, gases are released. Some of these include water vapour, hydrogen sulphide, sulphur dioxide and carbon dioxide. Azo sensors, 2017, states that, ‘By studying the composition of this gaseous mixture and monitoring fluctuations in their composition, scientists have discovered that they can better predict the likelihood of a volcanic eruption.’
Can predicting volcanic eruptions limit their destruction?
Volcanic eruptions can be very dangerous. In fact, when Mount Pelée erupted, 30 000 people died. Predicting volcanic eruptions would definitely assist in restricting their destruction. Having technology in place that allows an estimate at when one would erupt would allow experts to know when they should be monitoring the volcanoes even closer. From warning signs, experts can then authorise evacuations, saving many lives. An example of this happening is Mt. Pinatubo eruption where notification ‘enabled officials to evacuate more than 75,000 people’ (USGS, 2016). The same source stated that ‘In the fall of 2010, Indonesia’s Mt. Merapi had its largest eruption in over 100 years. More than 70,000 people were able to get to safety before flows of hot rocks, ash and volcanic gas rushed down the mountain toward their villages.’ BBC, 2018, meanwhile, stated that ‘volcano observatories, researchers and international organisations work tirelessly to respond to emergencies and forecast events, with many tens of thousands of lives saved as a result.’ These examples can be used as evidence to show that warnings could limit volcanic destruction, however we do not know what the statistics would be if these systems didn’t exist. It can be assumed to be catastrophic. These sources are reliable as they are from government and news websites, and therefore would need to have correct information. Although this wouldn’t help to save materialistic objects such as houses and cars, it could assist in limiting the destruction of lives