All data is from the Wikipedia and the Met Office's North Atlantic surface pressure charts.
I would have been better to get the high VEI numbers searched rather than specifying volcanoes. But we all have to start somewhere. …
The 2010 eruptions of Eyjafjallajökull were volcanic events at Eyjafjöll in Iceland which, although relatively small for volcanic eruptions, caused enormous disruption to air travel across western and northern Europe over an initial period of six days in April 2010. Additional localised disruption continued into May 2010. The eruption was declared officially over in October 2010, when snow on the glacier did not melt. From 14–20 April, ash covered large areas of northern Europe when the volcano erupted. About 20 countries closed their airspace (a condition known as ATC Zero) and it affected hundreds of thousands of travellers. The grounding of European flights avoided about 344×106 kg of CO2 emissions per day, while the volcano emitted about 150×106 kg of CO2 per day.
Seismic activity started at the end of 2009 and gradually increased in intensity until on 20 March 2010, a small eruption started rated as a 1 on the Volcanic Explosivity Index.
Beginning on 14 April 2010, the eruption entered a second phase and created an ash cloud that led to the closure of most of Europe's IFR airspace from 15 until 20 April 2010. Consequently, a very high proportion of flights within, to, and from Europe were cancelled, creating the highest level of air travel disruption since the Second World War.
The second phase of the eruption started on 14 April 2010 and resulted in an estimated 250 million cubic metres (330,000,000 cu yd) (¼ km3) of ejected tephra. The ash plume rose to a height of approximately 9 kilometres (30,000 ft), which rates the explosive power of the eruption as a 4 on the Volcanic Explosivity Index.
By 21 May 2010, the second eruption phase had subsided to the point that no further lava or ash was being produced. More seismic activity was produced.
By the morning of 24 May 2010, the view from the web camera installed on Þórólfsfell showed only a plume of water vapour surrounded by a blueish haze caused by the emission of sulphurous gases.
Due to the large quantities of dry volcanic ash lying on the ground, surface winds frequently lifted up an "ash mist" that significantly reduced visibility and made web camera observation of the volcano impossible.
By the evening of 6 June 2010, a small, new crater had opened up on the west side of the main crater from which explosive activity was observed with the emission of small quantities of ash. Seismic data showed that the frequency and intensity of earth tremors still exceeded the levels observed before the eruption, therefore scientists at the Icelandic Meteorological Office (IMO) and the Institute of Earth Sciences, University of Iceland (IES) continued to monitor the volcano.
In October 2010, Ármann Höskuldsson, a scientist at the University of Iceland Institute of Earth Sciences stated that the eruption is officially over, although the area is still geothermally active and might erupt again.
In May 2011, a nearby volcano named Grímsvötn started erupting, causing air travel disruption mostly in Iceland.
The 2011 eruption of Grímsvötn is an eruption in Grímsvötn, Iceland's most active volcano, which caused disruption to air travel in North-Western Europe from 22–25 May 2011. The last eruption of Grímsvötn was in 2004, with the previous most powerful eruptions in 1783, 1873 and 1902. The Grímsvötn eruption is the largest eruption in Iceland for 50 years.
The eruption is estimated to have started under the glacier at around 17:30 UTC on 21 May 2011 when an intense spike in tremor activity was detected. At around 19:00 UTC, the eruption broke the ice cover of the glacier and started spewing volcanic ash into the air. The eruption plume quickly rose to 65,000 feet (20 km). A series of small earthquakes had commenced at the time of eruption. Glacial flooding was anticipated, which normally occurs within 10–12 hours after eruption, but never occurred as a flood had occurred the previous autumn, meaning a smaller chance of another flood appearing.
On 25 May, the Iceland Met Office (IMO) confirmed the eruption had paused at 02:40 UTC. Later the BBC reported that the volcanic activity appeared to have stopped. At 15:00 the IMO issued an update stating that no further ash plume is expected. However there are still pulsating explosions producing ash and steam clouds, some reaching a few kilometers in height, rising up from the vents. Also there is still widespread ash in cloud layers up to 5 km from the eruption site.
On 26 May the Icelandic Meteorological Office and the University of Iceland reported that ashfall is only occurring adjacent to the eruption site. Visual observations indicate that little ice meltwater was produced during the eruption, so that an outburst flood (jökulhlaup) is not expected. Joint status reports will no longer be issued, unless something notable is observed.
The eruption ceased at 7am on 28 May 2011.
So what we have is:
2009: activity started.
20 March 2010, Volcanic Explosivity Index 1.
14–20 April 2010 relatively small eruptions of Eyjafjallajökull.
14 to 21 Apr 12:29. 14 to 20 April ash cloud & Volcanic Explosivity Index 4.
21 May 2010, no further lava or ash, more seismic activity.
24 May 2010, water plume of vapour surrounded by a blueish haze caused by the emission of sulphurous gases.
6 June 2010, new crater.
In October 2010, officially over.
Eruptions of Grímsvötn:
2011, 2004, 1902, 1873 and 1783.
21 May 2011. Plume to 65,000 feet.
On 25 May, the eruption had paused at 02:40 UTC.
28 May 2011, eruption ceased.
That's all for now I will edit it later to include some North Atlantic charts.
I am pretty disappointed with the animation.
I have some 40 odd charts on there though so I may have hamstrung the tool creating it. Maybe if I just took one chart from each day. Or posted the most germane of them?
The charts DO show a centipede though. Huge ones. All the way up to Greenland along the Mid Atlantic Ridge. And what's more the feelers are facing west.
Now maybe, I can get some sleep?