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

http://theextinctionprotocol.wordpress.com/2012/06/26/harmonic-seismic-tremors-continue-under-el-hierro-volcanic-island/