Earthquakes and volcanos in the Canary Islands cause concern because studies have shown that if they struck El Hierro or La Palma — just north of El Hierro – there is a possibility that a large part of El Hierro island would slide into the ocean and trigger a huge tsunami that could travel across the Atlantic hitting the eastern seaboard of the US in six hours.
Earlier posts are here and here.

Recent earthquake swarms on El Hierro - image: Instituto Geográfico Nacional
Underwater Volcanic Eruptions Edge Closer To El Hierro Mainland
Two new underwater volcanic eruptions have occurred off the south coast of El Hierro, the smallest and southernmost island in the Canary Islands.
Seismologists say two separate fissures have been identified less than 3.7 kilometres and 2.8 kilometres from La Restinga, a town on the southeast of the island. Authorities have detected a sulphur odour in the area while dead fish have also been spotted floating on the surface of Las Calmas Sea.
The fresh eruptions occurred 48 hours after a subsea eruption, Spain’s first since an eruption on La Palma in 1971, occurred approximately 5 kilometres from La Restinga. The town’s 570 residents were subsequently evacuated as a precautionary measure in the event of volcanic activity moving closer to the island.
The eruptions take place amidst an unprecedented earthquake swarm in El Hierro. The number of earthquakes recorded since July 17, 2011 on El Hierro has now exceeded 10,300.
Hierro, a shield volcano, has had a single historic eruption from the Volcan de Lomo Negro vent in 1793. The eruption lasted approximately one month and produced lava flows. …….
…. A Red Alert was issued by local authorities for the town of La Restinga, where local residents were evacuated from on Tuesday evening. Spanish Prime Minister José Luis Rodríguez Zapatero and cabinet colleagues later attended an emergency briefing on the developing situation.
The IGN says all three of its seismic stations on El Hierro in the Canary Islands have registered a volcanic tremor of low frequency in the south of the island at La Restinga, the southern-most village in the Canaries.
Hundreds Remain Evacuated
Roughly 600 people were evacuated Tuesday on Spain’s El Hierro Island in the Canaries due to the eruption of a nearby underwater volcano. They remained outside their homes on Wednesday as authorities feared an impending eruption. …. In a press release issued on Wednesday, the Canary Islands government said that although no specific changes have been observed since Tuesday evening, precautions remain in effect: “Among the security measures to ensure the safety of the population remains the designation by the Maritime Authority of Santa Cruz de Tenerife maritime exclusion zone which is closed to shipping, fishing, diving, sports or recreation in the area within a radius of four nautical miles from the tip of La Restinga.”
Ferry crossings to the island also remain suspended. People were, however, allowed to return to their homes on Wednesday under the protection of civil safety officials to retrieve medicines, clothing, and other necessities.
Some took to message boards on Tuesday and Wednesday claiming that a landslide in the Canary Islands could cause a mega-tsunami that would devastate the Eastern Seaboard of the United States. ……