From Foreign office site:-http://www.fco.gov.uk/en/travel-and-living-abroad/travel-advice-by-country/europe/spain
We are advising against all travel to La Restinga in the south of the island of El Hierro in the Canary Islands.
There continues to be seismic activity on the island of El Hierro, Canary Islands. Following a volcanic tremor near the south side of the island of El Hierro on 11 October, the local government authorities have raised the risk level from yellow to red and have evacuated residents and visitors from the area of La Restinga.
Over the past 12 months there have been over 9,000 tremors, the largest measuring 4.3 on the Richter scale on Saturday 8 October. The Canary Government has confirmed three small scale underwater eruptions. The first on the 10th October, 3 miles from the coast of El Hierro at a depth of 900m. The second and third on the 12th October 2 miles from the coast at a depth of 750m and 1.5 miles from the coast at a depth of 500m. The local authorities have put in restrictions on fishing, sailing and underwater activities around the area of La Restinga.
The Canary Government asks residents and visitors to be vigilant and are encouraging everyone to check the following Government website for future updates. See Natural Disasters - volcanoes. We continue to liaise with the authorities and monitor the situation closely.