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Italy ponders volcanic threat from Ischia 28 April 2010

Posted by admin in Ischia, Italy, natural hazards, volcano monitoring, volcanoes.
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At the northern end of the Gulf of Naples in southern Italy lies the island of Ischia, a complex volcanic edifice with a long history of violent activity that last erupted in 1302 AD. It has a population of around 60,000 and is a popular tourist destination. Now the head of Italy’s civil protection service, Guido Bertolaso, is sounding alarm bells about the potential volcanic threat from Ischia in the Italian media (only a few weeks after his Istituto Nazionale di Geofisica e Vulcanologia counterpart Dr Enzo Boschi did the same thing over Mount Marsili).

During a press conference in which he discussed the range of volcanic risks faced by Italy, Bertolaso described Vesuvius ‘the biggest civil protection problem in our country’, but pointed the finger at Ischia as potentially the more immediate threat: ‘If I were to say what is potentially the volcano with a bullet in the chamber, I would say that it is not Vesuvius but the island of Ischia’. He said that since the eruption of 1302 the height of Mount Epomeo, the highest point of the island (which is a volcanic horst) has increased by 800 metres [EDIT, this should almost certainly be 300 metres, see comments below. FURTHER EDIT, the uplift is to ~780 metres a.s.l., but that’s over the past 33,000 years – see note at the end of this post.] and that the magma chamber is ‘reloading’. However, whereas everybody knows that Vesuvius is an active volcano there is not the same perception of Ischia: this is clearly something that Bertolaso wants to change.

Bertolaso also discussed the need for better monitoring of active undersea volcanoes, and floated the idea of a Europe-wide volcanic ash monitoring network, in the wake of the disruption caused by Eyjafjallajökull.

(INGV’s monitoring page for Ischia is here. There is no sign of any impending eruption at Ischia, as Bertolaso made clear in his remarks.)

NOTE: Ischia uplift. Poli et al (1989) note that ‘the rapid uplift of the central horst of Mount Epomeo … from about -200 m to 700 m occurred after 33,000 y. B.P., mostly in the last 20,000 years’ (p. 332). Poli et al also anticipated that the main potential volcanic hazard at Ischia was landslides and mudflows consequent on this rapid uplift, rather than the direct effects of volcanic activity, with future eruptions likely to be effusive rather than explosive, although there remains the possibility of ‘phreatic or phreatomagmatic crisis’ (p. 334). S. Poli et al, ‘Time dimension in the geochemical approach and hazard estimates of a volcanic area: the Isle of Ischia case (Italy)’, Journal of Volcanology & Geothermal Research, 36 (1989), pp. 327-335 [doi:10.1016/0377-0273(89)90077-2].

News
Bertolaso: allarme eruzione a IschiaCorriere della Sera, 27 April 2010
Bertolaso lancia l’allarme su Ischia ‘Un vulcano con il colpo in canna’La Repubblica, 27 April 2010
Vulcani: Bertolaso, parte il monitoraggio di quelli sommersi – AGI, 27 April 2010
Bertolaso propone sistema monitoraggio Ue per ceneri vulcaniche – Reuters, 27 April 2010
Ischia volcano eruption concerns – Press Association, 28 April 2010
Italy says Ischia volcano, near Naples, could blowThe Statesman, 28 April 2010

Information
Global Volcanism Program: Ischia – information about Ischia (0101-03=) from the GVP
Osservatorio Vesuviano: Ischia – Ischia monitoring information from the INGV’s Vesuvius Observatory

The Volcanism Blog

Comments

1. Lab Lemming - 28 April 2010

800 meters since the eruption? That’s over a meter per year!

2. admin - 28 April 2010

Very nearly. And the summit elevation of Mt Epomeo is only 789 metres anyway.

I think 800 metres may be an error for 300 metres. The Corriere della Sera report has: ‘In questi secoli il cono del monte Epomeo è cresciuto di 800 metri’. La Repubblica, however, has Bertolaso saying ‘l’isola di Ischia, dove l’ultima eruzione si è registrata nel 1.300, ma il monte Epomeo è cresciuto in altezza di 300 metri’, which is perhaps more likely. I’ve corrected the post accordingly.

Thanks for pointing this out!

[Further research has clarified things. See the ‘Ischia uplift’ note I’ve added to the post above.]

3. Boris Behncke - 28 April 2010

It seems after Boschi’s appeal last month for funding of monitoring of the Marsili seamount and the international media attention this received, the Italian government is moving; our friend Berlusconi surprisingly agreed to provide funding for such monitoring equipment and activity. It is correct that other volcanoes merit more attention as well, and Ischia is one of them – it is being monitored but there is virtually no public awareness that this is an active and potentially extremely hazardous volcano (mostly because it is very densely populated).

I don’t think Ischia will erupt soon – currently all monitoring parameters indicate a state of quiescence, like at Vesuvius. Maybe nothing will happen for many centuries. Maybe something will start moving in a couple of weeks or months. In any case, awareness and preparedness are warranted, so all these initiatives from various sources – Bertolaso this time, who is the Civil Defense boss, not a volcanologist, not even a geologist – are useful to create more attention in the public.

Certainly the uplift of Monte Epomeo has been rapid in geological terms, but it seems to have been going on at a rate of a few millimeters per year at best. We don’t know if there was uplift at the time of the dramatic earthquakes in the 1800s, most notably in 1881 and 1883, although this seems plausible, but it will have been on the scale of a few tens of centimeters, maybe a couple of meters. Since 1883 Ischia has been seismically very quiet.

4. admin - 28 April 2010

Many thanks, Boris! There does seem to be a concerted move to raise awareness of volcanic hazards in Italy. If the Italian Government is actually coughing up some cash that’s very good news.

5. Universalgeni - 28 April 2010

Earthquake has hit Katla, Iceland few hours ago. It will in all likelihood erupt. http://hraun.vedur.is/ja/Katla2009/stodvaplott.html

6. admin - 29 April 2010

It was a M 1.5 event, depth 5.8 km, and the first quake under Katla for some time. However, ‘It will in all likelihood erupt’ is putting it a little strongly, on the evidence of one earthquake. There has been no further earthquake activity, no tremor, nothing to show unusual activity at Katla.

7. James - 29 April 2010

Well, Katla WILL in all likelihood erupt. Whether that will be within the next 18 months or the next 180 years, however, remains to be seen!

8. aldo piombino - 29 April 2010

Bertolaso is conducting a war against Boschi. This is only a new phase of the show: he wants the money for monitoring for himself…

I only hope that somehow money will arrive for monitoring all the tyrrenian volanoes….

But it would be better that those resources will go to INGV and the italian marine geology research insitutes than to Bortolaso….


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