Each cycle began with a Plinian eruption, marking several centuries of activity. The last phase lasted between 1631 and 1944 that included relentless lava flows and inconsequential explosions. Nonetheless, these Plinian eruptions are extremely consequential, with their high explosivity, high eruption rates and large volumes of erupted magma, they are considered the most troublesome event related with Vesuvius.The inevitable pyroclastic falls, surges and flows after a Plinian eruption were all seriously considered, and a preliminary hazard map was drawn up. The damage would be absolute if one was to occur in the present day, which is why it could be considered lucky that the only activity that took place throughout the last cycle was of the Strombolian kind, which featured lava flows and eruptive fractures.
A hazard map was drawn up stressing the most dangerous areas situated around the central cone.(Tazieff and Sabroux 1983: 150-161) Despite these precautions, a lava flow on the slopes of Vesuvius is pretty deadly from the aspect that the area is so densely populated; the town Torre Annunziata has been destroyed four times, most recently in 1906, yet has been rebuilt after each occasion (Bullard 1962: 63). Hazard zoning maps are valuable for indicating logical land uses, and to civil-defence officials for calculating future eruptions, but it doesn’t make the job of monitoring by volcanologists and public officials any easier (Tazieff and Sabroux 1983: 149). Vesuvius Observatory, built between 1841 and 1845, aids this task.
Some of the top volcanologists in Italy work at the Observatory, but despite recent key technological advances in the last two decades, the aptitude to predict volcanic activity is still relatively elusive (Mayell 2002:1). The monitoring system is composed of geochemical and geophysical networks. “The geochemical networks control seismic activity, the ground deformations and the gravimetric and magnetic field variations. The geochemical networks monitor the variations in the composition and temperature of the fumaroles and aquifer gas emissions which could be related to the presence of magmatic fluids (Petrosino 2000:1).” Monitoring is extremely important, but it’s not always practical or affordable, yet so is the evacuation of large numbers of people, particularly in the midst of indeterminate volcanic threats. Above all, it is extremely costly and complex, especially when there are 3.
75 million people living within 30 kilometres of Vesuvius’ summit. (Mayell 2002:1). Despite the implications of evacuation, there is no other alternative when land-use patterns are long established, and the prospect of moving people permanently is simply not an option.The only feasible solution is to maintain an efficient monitoring system to detect any volcanic activity, and uphold public support, especially when the socio-economic consequences of an evacuation are so big.
The re-housing and feeding of the evacuees, along with the inevitable problems of looting from the vacant buildings and the loss of earnings from the frozen trade makes the prospect of accurate volcano prediction particularly important, especially when the consequences of failing to predict could be so catastrophic.ReferencesBullard F M (1962), “Volcanoes; In History, In Theory, In Eruption,” Thomas Nelson and Sons Ltd, Edinburgh Sheets P D and Grayson D K (1979), “Volcanic Activity and Human Ecology,” Academic Press, London Tazieff H and Saboux J C (1983), “Forecasting Volcanic Events,” Elsevier Science Publishers, Amsterdam Lobley J L (1889), “Mount Vesuvius,” Roper Drowley, London