Two new volcanic eruptions were confirmed on Wednesday off the south coast of the Canary Island of El Hierro.
Nearly 600 people from the southernmost village, La Restinga, remained out of their homes Thursday after they were evacuated on Tuesday.
Seismologists have found two separate fissures less than 2.3 miles and 1.7 miles from La Restinga.
I confirm the existence of two points of volcanic eruption at El Hierro, Laura Otero, a spokeswoman for the local authorities, told AFP.
The first eruption occurred at a depth of 700 meters (2,300 feet) and the other at a depth of 200 meters (655 feet).
Scientists from ING, CSIC, and the University of Cadiz are trying to determine if the subsea volcanic vent is widening and, if so, if it is widening in the direction of El Hierro.
Geophysicist Carmen Lopez confirmed that there is a single eruption with two points of emission of underwater nature, according to a press release issued on Wednesday.
Authorities detected a sulfur odor in the area and have also spotted numerous dead fish floating on the surface. Scientists said the fish were likely killed by gas escaping from the subsea volcano.
A spokesman for a volcanology institute, David Calvo, told Spanish National Radio on Thursday that while authorities remain vigilant, there was no cause for alarm.
Because the eruptions eased pressure in the area, further evacuations were unlikely.
Several tourists along with the 570 residents of La Restinga were evacuated on Tuesday after a 4.3-magnitude quake the previous day.
El Hierro, the smallest of the Canaries, has experienced over 10,000 earthquakes since July 19, a signal that magma is rising toward the Earth's surface.
The volcanic eruption near El Hierro on Monday was Spain's first since the 1971 eruption of the Teneguia Volcano on the nearby island of La Palma.
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.
An infamous BBC documentary Horizon explained that if earthquakes or volcanic eruptions struck La Palma -- just north of El Hierro -- there was a possibility that a large part of the island would slide into the ocean and trigger a huge tidal wave that could travel across the Atlantic in six hours.
Findings by the scientists behind the claims have since been widely dismissed.
Reports came in on Monday from crews aboard four separate ships that noticed the presence of dead fish floating on the surface. Pointing to uncertainty over the coming days, authorities raised the warning level to red alert on Tuesday for La Restinga, while the rest of the island remained just below that on yellow alert.
After Spain's Instituto Geographico Nacional (IGN) confirmed that an underwater eruption was occurring about three miles off the southern coast, local authorities summoned everyone in the area to a local football field on Tuesday and announced that they would evacuate the residents and tourists in La Restinga because of the risk of another eruption closer to the coast.
Facing a change in the seismic event that is affecting El Hierro Island, and as a preventative measure, we are carrying out the relocation of the population of La Restinga, a local government spokesman said in a statement.
La Restinga is the southernmost town in the Canaries.
Most of the evacuees found refuge with friend and relatives in other villages, though dozens of others, mostly tourists, spent Tuesday and Wednesday evenings in a student dormitory and a local gym.
78 people are in shelters, 31 of which are tourists, according to Typically Spanish News.
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.
El Hierro, which means iron is Spanish, was designated by UNESCO as a Biosphere Reserve in 2000 with 60% of its territory protected. Although over 200 years have elapsed since the last eruption, El Hierro has the largest number of volcanoes in the Canaries with over 500 open sky cones, another 300 covered by the most recent outflows, and some 70 caves and volcanic galleries.
El Hiero is home to roughly 11,000 residents. It is currently the most volcanically active of the Canaries.