Is there any means to early warning for a volcanic activity?
Yes you can get an early warning from local athorities
Long Valley Caldera's current volcanic activity level is normal with aviation color code of green. (Updated 2-9-12 CalVO) This simply means that there is no out of the ordinary activity currently present in the Long Valley Volcanic Complex. For further information on the Long Valley Volcanic System as well as its monthly activity updates see the CalVO (California Volcano Observatory) website in the related links section.
Tectonic plates are pieces of the earth's crust that move and there can be volvcanic and earthquake activity where tectonic plates meet. Where tectonic plates meet, subduction occurs. This means that one plate slides under the other and returns to the inner level of the earth, the mantle. The Pacific Ocean has the most trenches and the highest level of volcanic activity of all the oceans.
A warning is generally the worse advisory. Although it differs depending on which sort of watch or warning is issued, a watch means a particular event is possible. For example, if there is a tornado watch, it means that conditions are favorable for a tornado to form. A warning means the event is expected or probable. In a tornado warning, for example, it means that a tornado has been spotted or is forming.
In the ring of fire, there's a lot of seismic activity. The definition of seismic means (well, i don't know the LOGIC definition, but heres a close meaning) the ring of fire has a lot of volcanic activity. If this is not a very good help, I'm sorry, but it's better that nothing. The prevalence of volcanic activity in the ring of fire has to do with the continental plates which collide with eachother, very…