Moi, Paul Derand

It's when trying to cross VEImax and frequence of eruptions that I had the idea of creating a mean tephra volume/year index

The mean tephra volume/year index would simply be the mean tephra volume erupted per year on logarithm scale.

However, it doesn't always mean that a volcano is dangerous or not: Because small eruptions are quite insignificant in term of erupted volume, we could say that this index only concerns large eruptions. However, frequent small eruptions are only a little less as dangerous as infrequent large eruptions. So, in order to evaluate the power of eruptions of all strengths, and not only the erupted volume, I could create a volcanic activity index which would be the logarithm of (the sum of all recorded eruptions' VEIs mutiplied by the number of years they span, divided by the number of years of eruption records and multiplied by 100).

For example, for Santa Maria, that had 92 years of continous VEI=3 eruptions, 10 years of continous VEI=2 eruptions and 1 VEI=6 eruption in the last 112 years:

Volcanic activity index=log((92*3+10*2+6)/112*100)=2,43

Stiil one last problem: this only works with explosive volcanoes, as VEI only cares about tephra. Strong effusive volcanoes such as Kilauea may be as dangerous, frequently active and powerful as some explosive volcanoes but are classified as 0 on the volcanic activity index. So instead of using the logarithm of (the sum of all recorded eruptions' VEIs, divided by the number of years of eruption records and multiplied by 100), we would use the logarithm of (the sum of all recorded eruptions' EVIs mutiplied by the number of years they span, divided by the number of years of eruption records and multiplied by 100). EVI would stand for eruption volume index. The EVI (eruption volume index) itself would be the equivalent of the VEI, but would include all eruptive material, not only tephra..

So we now have:

Volcanic activity index = log((EVI1+EVI2+EVI3+...)/number of years of eruption records*100)

Here is a list of some volcanoes, classified by their Volcanic Activity Index:

Class 2 to 2,99 (24 volcanoes):

Class 2,4 to 2,59 (5 volcanoes): Dukono (2,48), Tungurahua (2,47), Vesuvius (2,46), Sangay (2,45), Santa Maria (2,43)

Class 2,2 to 2,39 (8 volcanoes): Semeru (2,4), Stromboli (2,38), Etna (2,33), Karymsky (2,31), Manam (2,31), Nevado del Huila (2,3), Suwanosejima (2,29), Kliuchevskoi (2,27), Sakurajima (2,25)

Class 2 to 2,19 (10 volcanoes): Arenal (2,14), Aso (2,13),  Sinabung (2,12), Ol Donyo Lengai (2,1), Ubinas (2,08), Merapi (2,06), Fuego (2,05), Nyamuragira (2,03), Karangetang (2), Ulawun (2)

Class 1 to 1,99 (58 volcanoes):

Class 1,9 to 1,99 (8 volcanoes): Reventador (1,98), Asama (1,98), Nevado del Ruiz (1,97), Krakatau (1,97), Lokon-Empung (1,96), Marapi (1,96), Nyiragongo (1,94), Villarica (1,9)

Class 1,8 to 1,89 (7 volcanoes):Llaima (1,9), Popocatépetl (1,87), Bulusan (1,85), Colima (1,85), Kanlaon (1,85), Telica (1,83), Galeras (1,81)

Class 1,8 to 1,89 (1 volcanoes): Ruapehu (1,75)

Class 1,6 to 1,69 (8 volcanoes): Rabaul (1,7), Mayon (1,68), Grimsvotn (1,66), Copahue (1,64), San Miguel (1,63), Tarumae (1,63), Michoacán-Guanajuato (1,61), Piton de la Fournaise (1,6)

Class 1,5 to 1,59 (5 volcanoes): Cotopaxi (1,53), Dona Juana (1,53), Vestmannaeyjar (1,53), Puracé (1,52), Gamalama (1,5)

Class 1,4 to 1,49 (1 volcanoes): Kilauea (1,47)

Class 1,3 to 1,39 (7 volcanoes): Kikai (1,39), Bam island (1,35), Karthala (1,34), Savo island (1,34), Banda Api (1,32), Kelut (1,32), Avachinsky (1,3)

Class 1,2 to 1,29 (9 volcanoes): Caminguin (1,29), Agung (1,28), Taal (1,27), Awu (1,26), Agung (1,26), Dempo (1,25), Mt Cameroon (1,25), Guagua Pichincha (1,23), Calbuco (1,21)

Class 1,1 to 1,19 (9 volcanoes): Mt Pelée (1,17), Orizaba (1,17), Galunggung (1,17), El Chichon (1,16), Mauna Loa (1,15), Bardarbunga (1,15), Ceboruco (1,14), Ibu (1,12)

Class 1 to 1,09 (5 volcanoes): San Salvador (1,1), Santorini (1,09), Koryakski (1,09), Acatenango (1,08), Turrialba (1,03)

Class 0 to 0,99 (24 volcanoes):

Class 0,8 to 0,99 (7 volcanoes): Hekla (1), Makian (0,99), Askja (0,96), Sundoro (0,85), Okataina (0,84), Soufrière St Vincent (0,81), Soufrière Guadeloupe (0,81)

Class 0,6 to 0,79 (9 volcanoes): Fogo (0,79), Santa Ana (0,72), Guntur (0,71), Eyjafjoll (0,71), Fuji (0,66), Ijen (0,66), Tacana (0,65), Ilopango (0,64), Nevado del Tolima (0,62)

Class 0,4 to 0,59 (6 volcanoes): Papandayan (0,57), Teide (0,55), Unzen (0,53), Cumbre Vieja (0,51), Cumbal (0,46), Cosiguina (0,44)

Class 0,2 to 0,39 (1 volcano): Almolonga (0,2)

Class 0 to 0,19 (1 volcano): Huaynaputina (0,16)

Class -1 to -0,01 (2 volcanoes):

Rainier (-0,08), Campi Flegrei (-0,2)

Class -2 to -1,01:

Paul DERAND