La Palma is a volcanic island that is part of the Canary Island chain. Large portions of the island are unstable, and with the right conditions, could cause a massive landslide into the sea. High end estimates range between 50 and 200 km^3 of material, ultra high end estimates at 600+. The displacement, if it happens all at once, would cause a mega tsunami.
Recently over 5000+ small earthquakes have been happening under the island, indicating a magma swelling, which could lead to eruption and/or collapse.
Explanation of what would happen.
If the earthquakes are happening now, why would there be a tsunami?
The tsunami caused in this scenario is driven by the displacement of water due to the collapse of parts of La Palma into the ocean. This is 2.8 km^3 of material sliding during the Mt. St. Helens collapse.
If you live directly on the coast, and the worst case scenario happens, potentially very bad. Travel times are 0.25-5 hours to Africa, 1-2 hours to Spain/Portugal, 3-4 Hours to Britain, 5-8 hours to Brazil and 9-10 Hours for the US. To estimate damage, treat it as worse than a Category 5 Hurricane storm surge in the US.
Infrequent Volcanic update reports
The Canary Islands Government has activated the Special Plan for Civil Protection and Attention to Volcanic Risk Emergencies (PEVOLCA) in the Cumbre Vieja area (La Palma) due to the increase in seismic activity registered in recent days.