Look at a satelite image of La Palma and you can see on the western side of the island a massive area that slipped into the sea and left a concave area towards the central part of that island.The same on Teneriffe but the eastern side and Gran Canaria has been hit by a tidal wave in the past as...
Lava moving under the volcanoe (as above) causes tremors.That does not mean that it will erupt.Look at Yellowstone and the mini quakes they get.
On the other hand it may mean it will erupt.Science is great,there is always an answer.