El Hierro eruption

[Janet]

It's incredible how quickly these phenomena can rise and die away. It seems that this swarm is already dying away, but it shows the pattern for the future, it seems: this is an eruption that will happen at some point. It appears that the magma seeking release from beneath El Hierro is finding two routes of escape, the first in the El Golfo bay region, and the other directly under the island land mass, which of course is the crater part of the old volcano itself. There have been three quake swarms so far, the first one resulting in the eruption in the Las Calmas sea south of La Restinga , the second one was just in the form of tremors that had no surface phenomena, and now this short-lived third one which has seen a clear movement southwards.  It will be back ... JA

[Janet]

As I said in my last post on this on 18 September, "it's incredible how quickly these phenomena can rise and die away ... it shows the pattern for the future". And now we have another swarm, with eleven tremors recorded over the last 24 horus under the centre of El Hierro, all moving southwards. None were over 1.8 on the Richter scale. It will become clear over the next day or so whether this builds up into another eruptive stage, or dies away as quickly as the last flurry. JA

[Janet]

It's been rumbling away for the last few days, with a 2.6 tremor on Thursday 13th which was felt by the public.  Experts say this set generally is showing the same patterns as in the last swarm. JA

[Janet]

Today has been a very busy day for seismic activity, with 20 earthquakes today in the El Golfo region of magnitudes ranging between 1.5 and 2.5 on the Richter scale. 2012 is ending with a clear swarm, as El Hierro shows that it will almost certainly have more in store during 2013. JA

[Janet]

Since the 31st's update, there have been one or two lulls, but generally there are tens of these quakes each day now, all at a depth of between 15 and 20 km or so, and up to a maximum of around 2.5 on the Richter scale, with a general albeit slight increase in strength. What marks this swarm out as interesting is that they're centred on the hitherto less affected north El Golfo region. Yesterday saw quite a strong harmonic tremor, which has almost died away today; experts say that this suggests magma is trying to find a way out and has currently been halted. Only time will tell how and where it will make itself felt next.  JA

[Janet]

A football-field sized turquoise-coloured patch has appeared off the south coast of El Hierro. IGN says that this is a periodic degassing associated with the eruptive process but does not necessarily indicate a resumption of volcanic activity. The President of the El Hierro Cabildo, Alpidio Armas, has called for calm, and reminded the public that this is not the first time that such patches have been seen in the area. JA

[El Profesor]

I was reading somewhere that they had calculated the mass of lava expelled during this eruption last year, and worked out that it would take about 9,000 similar eruptions to make another island the size of El Hierro. Normally they would be spaced out at about 150 years between each one.
It was in the paper a couple of weeks ago, sorry no link.

[Janet]

After a few days of clustered tremors, there was just one today, but it was strong for this series, at 2.9 on the Richter scale. The earthquake occurred just before 4.30 at a depth of 15km: its epicentre was located off La Restinga on the turqouise patch. Experts say that the harmonic tremor graphs show changes too, and that the episode suggests that something "interesting" is happening. JA

[Perikles]

something "interesting" is happening.

I bet that is a rough translation of at least one person's last words in Pompeii, 79 AD. 

[Janet]

IGN's volcanic measurement network  has registered a new clutch of seismic activity in El Hierro today with a total of 28 tremors of between 1.9 and 2.6 degrees on the Richter scale. None were felt by the public. The largest of the quakes, 2.6, occurred at 2.29pm to the west of Frontera, under land, at a depth of 20 km. It was followed at 2.42pm by a 1.9 tremor at a depth of just 2km to the north west of Frontera. The rest of the seismic activity was mainly to the northwest of the municipality and to the southwest of El Pinar. There were three quakes yesterday too, the largest of 3.8 degrees on the Richter scale to the west of Frontera, again under land, at a depth of 13 km. IGN says that there have been 30-odd tremors over the last several hours. JA