How do you know when a volcano erupts?
If there are any volcanoes in Ireland, how many are there?
Have there been any eruptions in Ireland so far?
Thuy Ngo
Hi again Thuy,
Well, there are lots of ways to know if a volcano is erupting. The most obvious
way is if you can see ash or lava coming out of it. Many times the weather may
be bad or cloudy, or maybe it is nighttime so you can't actually see the
eruption. In that case scientists usually rely on seismometers. Volcanic
eruptions generate a lot of earthquakes. These are almost always pretty small
earthquakes that you can only feel if you are right on the volcano. There is a
certain type of earthquake signal called "harmonic tremor" that is only caused
by magma moving through a volcano. If you record harmonic tremor on your
seismograph then you can be almost certain that an eruption is going on
somewhere.
Still no volcanoes in Ireland...
Sincerely,
Scott Rowland, University of Hawaii
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