Countries which r near boarders because the convergence of plates causes volcanoes to form. When a volcano is going to erupt determines on how much pressure there is underground, in the mantle. To tell when a volcano is going to erupt is hard to tell but an estimation can be given by observing the rocks around the volcano to see how often it erupts and the change in conditions in the environment such as how acidic near by rivers or lakes are, the expansion on the side of a volcano, the levels of carbon dioxide and amount and levels of micro-quakes in the area. These signs not necessarily mean that the volcano is going to erupt in the following wk (it is possible but you never noe) but could erupt in a couple of months.
