Disaster Management Options for Volcano

Disaster Management Options for Volcano Hazards

Currently there are many options in forecasting volcanic natural disasters like eruptions and explosions. None of the current methods are accurate enough to predict a volcanic event every time and in quickly enough to evacuate nearby populations. This is problematic since so many volcanic areas are well-populated. These include the Alban Hills south of Rome, Italy, the "Ring of Fire" in the Cascade Mountains of the northwest United States, and the Tungurahua volcano in Ecuador (Choi, 2004; Kerr, 2003). To make matters worse, few volcanoes around the world are monitored well or at all (Mileti, 1999). While current methods are not perfect, they offer detection in many cases. If they are implemented and understood, new developments and methods may be developed that can better predict volcanic events and save the lives of those who witness such a natural disaster.

Mileti (1999) suggests that there are two main factors in volcanic disaster warning and prediction: "forecasting explosive events and assessing volcanic hazard" (185). Methods to detect whether there is a volcanic hazard are more accurate than methods attempting to predict an explosive event (Kerr, 2003; Mileti, 1999). Assessing a volcanic hazard simply means to assess whether a volcano is still active and should be monitored or watched for possible future activity. This is more difficult with volcanoes that have large caldera systems and that do not erupt often (Kerr, 2003; Mileti, 1999). Predicting where and when an explosive or eruption event will happen is more difficult. Yet, knowing when a volcano will erupt and how it will erupt is the most important issue in volcanic forecasting because it has the potential to save lives. Most of the current forecasting methods look for confirmation that fresh magma (liquid rock) has traveled to chambers in the upper crust, about 3-6 miles below the earth's surface (Kerr, 2003).

Seismic monitoring is one of the most common ways to keep track of volcanic activity (Choi, 2004; Mileti, 1999). Seismometers monitor earth movement, including the earthquakes and tremors that sometimes indicate volcanic activity like underground magma movement (Choi, 2004). Though seismic activity is often linked to volcanic events successfully, not all seismic events indicate a coming eruption (Kerr, 2003). For this reason, seismometer readings do not always provide accurate predictions (Choi, 2004).

Seismic tomography is a related method which uses tremor activity and seismic waves to "image" the underground workings of a volcano; since the waves travel at different speeds through magma than through rock, registering an earthquake from several different stations in one area can illuminate where volcanic magma chambers are. This, in turn, can help to predict where eruptions might occur (Kerr, 2003). Electromagnetic monitoring can also be used with seismic monitoring and tomography. By using strainmeters buried deep in the earth around a volcano, a "long-period seismic event" (LP) can be monitored (Kerr, 2003, 2017). This monitoring allows scientists to make better predictions for volcanoes that are regularly active.

Ground deformation monitoring uses satellite and air images, as well as topographic data, to assess whether the area around a volcano is bulging or swelling from built-up magma and gasses (Kerr, 2003). Magma and gasses building up just below the surface before an eruption can cause a bulge many miles in diameter. Since they are so large, these swells cannot be seen by the naked eye (Kerr, 2003). Satellite-borne radars alert volcanologists when such bulges appear. The satellites monitor global positioning (GPS) devices on the ground, using triangulation to mark whether the ground is bulging. Yet, again, the lack of a bulge does not mean that there will not be an eruption so this method is only helpful in some cases and where a volcano is well-monitored (Kerr, 2003).

Geochemical monitoring involved watching the changes of gasses associated with volcanic movement. Watching inactive volcanoes for the escape of gasses can be a precursor to eruption (Choi, 2004). Sulfer dioxide, carbon dioxide, and other gasses escaping from the earth signal the movement of magma underground, sometimes meaning that an eruption is imminent (Choi, 2004; Kerr, 2003). The instrumentation used to monitor escaping gasses is not ideal, however; it is both unwieldy and fragile and so is ill-suited for monitoring outside of laboratories (Choi, 2004). Additionally, Kerr (2003) finds that gas observation can be misleading since both increases and decreases in gaseous activity can signal a coming eruption.

New methods are being developed due to the inadequacy of current available methods in forecasting volcanic events. Many new methods arise as an improvement or improvisation on current working methods. Choi (2004) reports on how one new method, quantum-cascade laser detection, may be able to expand upon the technique of monitoring escaping volcanic gasses. This method could monitor the changes in carbon isotopes and carbon dioxide in volcanic gasses. Very slight changes (as little at 0.1 part per million) in the ratio between the two gasses could mean the movement of magma below the surface, assisting in the prediction of volcanic eruptions. (Choi, 2004). These ratio changes cannot be measured by the means used to detect escaping gasses. Instead, scientists are hoping to use quantum-cascade lasers to detect the variations (Choi, 2004). Since the two types of carbon in volcanic atmosphere (carbon 12 and carbon 13) absorb light at different wavelengths, a stable laser may be able to monitor variations in the ratio between the two carbons. By using a quantum-cascade laser, they hope to create a monitoring tool that is stable, compact and accurate.