There are many pro’s for attempting to forecast an earthquake or volcano. Forecasting an earthquake or eruption saves lives and property, mainly by preparation, as there is no way to prevent these events with today technology.
On February 4th 1975 in Haicheng China there was a magnitude 7.5 earthquake. Over a period of months there were changes in elevation in land, ground water and unusual animal behavior which are all precursors to an earthquake. Days before the 7.5 magnitude earthquake there were foreshocks that triggered an eviction warning that effectively saved over 150,000 lives or injuries. This is a pro as this forecast saved thousands of lives and had the people of this area (knowing this was a place of seismic activity) took precautions, like that of earthquake resistant buildings, evacuation points, preparing disaster supplies among other preparations the following may not have happened or would have been less of a disaster.
There are also many cons for attempting to forecast earthquakes and volcanic activity. A couple of possible cons are false warning or evacuations which cost the people money as well as their economy (Example: if this was a tourist attracted place, then they would have less tourists and thus less money). I spoke of an example of a pro for the forecasting of the Haicheng earthquake above, this was also a con as I will explain in this next paragraph.
After the Haicheng earthquake forecast, the area essentially would feel more optimistic on the forecasts of earthquakes. The following year in July 28, 1976 a magnitude 7.6 earthquake struck the city of Tangshan and caused as estimated 250,000 fatalities and 164,000 injured, without a warning or forecast. As you can see the con in the situation I just described would be the fact that one good forecast created an overly optimistic population in regarding to forecasting earthquakes.
Volcanic forecasts are more accurate then earthquake predictions. These predictions are generally forecast in the same way as an earthquake (temperature increases in geothermic waters gaseous concentrations, changes in elevation of land and water etc… Because we generally know where Volcanoes are, we can predict when an eruption may take place.
In March 18, 1880...