When Will Mount Etna Erupt Again
Oft asked questions about Etna
When will Etna erupt again?
In spite of the much increased noesis and ever more sophisticate monitoring of Mountain Etna, this remains ane of the questions most hard to answer. At present (early on August 2003), the volcano is not erupting, and the most recent flank eruption concluded on 28 January 2003, after three months of vigorous activity. And then this question concerns both height activity, and a flank eruption, which are two dissimilar pairs of shoes.
Many flank eruptions at Etna are really preceded by eruptive activity at the summit craters (at times bars to one of the four summit craters, at others occurring at two or even more of them simultaneously), which may extend over periods of months to years. Superlative activity was observed for six years prior to the 2001 flank eruption and for nigh three months prior to its successor in 2002-2003. From these two recent cases lonely it becomes evident that there is no relation between the duration, grapheme and book of summit activity and any of the parameters of the ensuing flank eruption.
Unfortunately, volcanoes commonly do not conduct in a strictly regular fashion in terms of their eruption frequencies, and they may often change the beliefs manifested for a certain menstruation (take Vesuvio (Vesuvius) which was in about constant eruption for three centuries until 1944, but has been completely inactive since and then). At Etna, between 1971 and 1993 there were 13 well-defined flank eruptions, an average of one eruption every 1.v years (from 1993 to 2001, that is, for 8 years, at that place was none). Nearly (but not all) of these flank eruptions were preceded by activeness at the peak craters; in some cases at that place were existent cycles of acme activity followed by flank eruption (e.1000. 1980-1981, 1988-1989). When the pinnacle craters resumed activeness in 1995, it seemed that another bicycle had begun, and a flank eruption would occur within a few months to a few years. Withal, this fourth dimension the height eruptions lasted half-dozen years before at that place was another flank eruption, and we are now realizing that eruptive cycles at Etna are more than complicated.
The eight years which passed between the flank eruptions of 1991-1993 and 2001 were the longest interval without flank action since 1971. This did not mean that the volcano was "less agile", or that the magma supply had dropped. The volcano inflated vigorously, recovering more than twice the inflation lost during the big 1991-1993 eruption. Intense seismic activity in various sectors of the mountain indicated magma movements at depth, in some instances budgeted quite close to the surface. Etna was recharging with magma, but it appears that its internal plumbing system was (at least until July 2001) more than stable than it was from 1971 until 1993. It is likely that this state of stability has now been replaced by a country of instability.
After the summer 2001 eruption everybody wondered how long it would take to the side by side flank eruption. Based on the contempo eruptive behavior of the volcano, a new eruption could exist expected inside a few years later on the 2001 eruption. Only looking with some attending at the menstruation 1971-1993, one notes that during that interval flank eruptions occurred at an average charge per unit of one every 1.5 years. Assuming that the rate of magma supply into the volcano had not dropped since the 1971-1993 menses (it is rather likely that it has increased), a new flank eruption could thus occur as early as 1-2 years after the 2001 eruption. And it did. In late October 2002, the latest flank eruption began only 1 yr, 3 months and 10 days after the beginning of the previous eruption. This is less than the boilerplate interval betwixt flank eruptions during the flow 1971-1993. The new eruption connected until 28 January 2003, afterwards which the question "When will Etna erupt again" again became a question of high priority. Although no new magma has appeared at the surface anywhere on the volcano every bit of early August 2003, there are many indications that the volcano continues to be unstable, probably it is less stable now than any fourth dimension since 1993.
There are several possibilities how Etna will behave in the near future:
ane) in that location volition be a menstruum of height activity.
It is likely (just not sure) that the next activity that we will see on Etna will occur at the height craters. This activity might extend for months to several years and build upwardly to major events such as lava fountains and voluminous overflows of lava onto the upper flanks of the volcano, such equally in 1995-2001. On the other hand, summit activeness did occur betwixt the 2001 and 2002 flank eruptions but never reached the levels of the 1995-2001 activeness, possibly considering the volcanic edifice was much less stable then than before 2001. With the volcano beingness at least every bit unstable as between the 2001 and 2002-2003 eruption, magma rising into the volcano will much more easily detect pathways nether its flanks and the next menses of summit activity might be relatively brief and of pocket-size dimensions, or there might be no summit activeness at all .
ii) a new eruption will occur somewhere on the flanks on the volcano.
Such an eruption volition inevitably occur sooner or later, possibly after a flow of meridian activity. Actually information technology might take little time (1-ii years) until the volcano will get ready for some other flank eruption. Another, not all that reassuring possibility is that the next flank eruption volition exist larger than those of 2001 and 2002-2003, which were rather medium-sized for Etna, although the latter of them emitted about twice as much magma as the earlier.
3) the activity will eventually die down.
Currently (early on August 2003) there is no eruptive activity, so things tin only go in the opposite management. In the long therm Etna will go on to be the second virtually active volcano on World (later on Kilauea, Hawaii), and currently information technology seems that it is getting more active rather than calming down.
Then we know that a flank eruption volition certainly occur in the hereafter, merely at this moment neither the time nor the location and graphic symbol of that outburst can be foreseen. However, a few assumptions based on Etna's by and contempo behavior can be fabricated. The ii major fracture systems (or rift zones) on the northeastern and southern to southeastern flanks are more than prone to eruption than the other sectors of Etna: 18 out of the 23 flank eruptions in the 20th century every bit well every bit the 2001 and 2002-2003 eruptions have taken place in these areas. Before and during the 2001 and 2002-2003 eruptions extensive fracture systems developed from the NE to the S flank where all eruptive fissures of these eruptions became agile. It may well be that these fracture systems remain unstable, so that the easiest pathways for magma can exist plant there, and thus the next flank eruption might affect more than or less the aforementioned sectors of the volcano.
In summary, at this moment, there is no manner to recognize the precise time of the next eruption of Mount Etna. However, based on the available evidence from the contempo by and from the historical tape, Etna seems to be in a peculiarly active stage, which is characterized past periods when flank eruptions occur once every few years. Such a period was initiated with the flank eruptions of 2001 and 2002-2003, and there is no reason to assume that the volcano will slow down afterwards these events. Statistically, a new flank eruption is extremely likely inside the side by side i or ii years (from the stop of the most recent eruption in late Jan 2003). This may or may not be preceded by summit activeness, and clear geophysical evidence for renewed magma intrusion under the flanks may be available merely very shortly before the event, as in October 2002, when there were only two hours of seismic alert of the imminent eruption. The sites nearly likely to exist affected past a new flank eruption lie in the same full general area of the most recent 2 eruptions, that is, on the upper southern and on the northeastern flanks.
One of import question that remains in this context is: will there be a possibility to give more than precise, timely alarm of the next eruption, will it be possible to brainstorm to react earlier than in the instance of the 2002-2003 eruption? Can the adjacent eruption be predicted or forecast?
Copyright © Boris Behncke, "Italy's Volcanoes: The Cradle of Volcanology"
Page set upwards on 17 November 1997, last modified on 6 Baronial 2003
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Source: https://www.italysvolcanoes.com/ETNA_future.html
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