El Hierro volcano (Canaries): increase in small earthquakes, almost no visible activity
Thursday Feb 16, 2012 00:44 AM | BY: T
The submarine eruption south of El Hierro Island could be in a process of change: While visible activity on the sea surface above the vent, as well as harmonic tremor signal (thought to be more or less proportional to erupting magma flux) have nearly ceased, the number of earthquakes under the island has increased sharply since yesterday.
On 15 February, more than 20 quakes were measured. Most of the earthquakes were very small, well below magnitude 2, and were clustered beneath the NW and SW sectors of the island at depths of around 10 km.
There is no conclusive interpretation of this measurement. A possible (and usually assumed) scenario is that rising new magma from the mantle reservoir is creating new intrusions and rupturing rock to create pathways in the crust under El Hierro, not using the same paths as until now. That would explain why less magma is currently being erupted at the current vent(s). In that scenario, the eruption will continue, perhaps even from a different vent, and an increase in magma output is going to be expected any time soon. However, this is speculation.
The earthquakes could as well be related to some other (known or unknown) process, e.g. gravity-induced adjustments that respond to pressure changes and occur within previously ruptured areas of the crust beneath the island.
The next days or weeks will show what happens next.
Links / Sources:
Wednesday, Feb 15, 2012
The new USGS / GVP weekly activity updates report is now available. The summary: ... [more]
Sunday, Feb 12, 2012
Wednesday, Feb 01, 2012
Why not combine your interest in photography with a winter visit to Iceland? On this tour you get to visit some of Iceland´s most famous sights whilst in winter mode. ... [more]
Wednesday, Jan 18, 2012
Saturday, Jan 07, 2012
Support us?Maintaining the volcano and earthquake news sections on this website, the free Volcano Webcams tool and interactive map widget is a free-time, both time- and server cost intensive effort.
If you find the information useful and would like to support us, and help keep it alive and improve it, please consider making a small donation. Thank you!