Harmonic seismic tremors continue under El Hierro volcanic island

June 26, 2012 – CANARY ISLANDS – While the unusually strong earthquake swarm under El Hierro Island continues, harmonic volcanic tremor has reappeared short time ago at about 16h10 UTC. The tremor, a low-frequency ground vibration, is thought to be caused by moving magma. It had been strong yesterday and correlated well with a southward propagation of earthquake locations, suggesting that magma at about 20 km depth flew from underneath the El Golfo area towards the EL Julan (south) coast, in a similar way as before the Oct 2011 eruption, but became blocked there, and did not reach the southern rift zone near La Restinga. After the cease of tremor in the afternoon, earthquakes still continued at high rate, marking a record figure with over 180 quakes larger than M2 yesterday alone, and more than 150 quakes larger than M1.5 so far today. In other words, pressure continued to cause wide-spread rock fracturing underground and cause small intrusions of fluids. Now, the re-appearance of tremor could mean that magma is moving again somewhere underneath the island. Where to and whether or not it might reach the surface and initiate a new eruption is difficult to know at the moment. It is essential to continue to monitor location and magnitude of earthquakes. –Volcano Discovery 

Update: Over 220 earthquakes in 24 hours: The volcano monitoring network monitoring 24 hours of National Geographic Institute (IGC) has recorded on Tuesday on the island of El Hierro, specifically in the municipalities of Frontera and El Pinar, a total of 221 earthquakes. The largest, recorded at 16.50 and 16.35 hours and at a depth of 19 kilometers, had a magnitude of 3.5 degrees on the Richter scale and were felt by the population of border southwest and west of El Pinar. Also, on Wednesday and have been recorded on the island of Meridian a total of 65 earthquakes of between 3.4 and 1.6 degrees, Frontera and El Pinar. The elderly, and felt by the population, took place at 00.11 and 02.27 hours southwest of the town of Frontera and about 19 kilometers deep and 20 respectively. –Noticias (translated)