18 comments on “Perished in Style – Ritter Island, P.N.G.

    • Only the Storegga was 1100 times bigger 🙂 As to the origin, both slides were probably triggered by earthquakes unsettling poorly consolidated layers and faults, in Ritter it was stratified basalt/andesite and tephra and in Storegga loose material created and moved to the edge by glaciers.
      Thanks for your kind words and Happy new year to you as well!


  1. An alert level YELLOW has been called by SERNAGEOMIN for the volcano Nevados de Chillán, located in the municipalities of Pinto and Coihueco, in the Bio Bio region of Chile. Its last eruptions were a total of VEI2 from 1973-86, two weeks producing a VEI 1 in 2003 and an unconfirmed event in 2009. Nevados de Chillán is a volcanic complex that features 4 stratovolcanoes, 11 named cones, 3 calderas 3 domes and a thermal area.
    During December 2015, 1259 seismic events were recorded, of which 186 were associated with fracturing processes (volcano-tectonic earthquakes, VT) the strongest a ML 1.8 at a depth of 4 km. Also, 1030 long-period (associated with fluid dynamics, LP) and reduced DRC less than or equal to 61 cm^2. Also 40 short episodes of spasmodic tremor and 3 tornillo events (TO). Most of the the events were concentrated near the southern cone of the complex less than 5 km away.

    Click to access 20151231054207833RAV_Biobio_2015_diciembre_2015_vol_23.pdf

    Aerial view of the Nevados de Chillán chain. Left to right: Volcán Nevado, Volcán Nuevo, Volcán Chillán. The Volcán Arrau dome complex (1973-1986) can be seen as a sharp cone-shape in front of the Volcán Nevado:


  2. Excellent post as always. Two thoughts. First, specific to Ritter: one contributory factor may well have been its unusually steep slopes -apparently these pre-collapse drawings are not exaggerated.
    On a more general point, has anyone else considered that volcanologists had until St Helens something of a blind spot regarding such collapses?, They were known to happen,, several had even been studied–. but textbooks published before 1980 barely mentioned them. Field guides describing avalanche deposits were wont to call them the result of exceptional lahars (Galungung, Ruapehu), even the USGS admitted that before St Helens they had no explanation for the Shasta Valley debris field. Nowadays, post 1980, by contrast, it seems that every self-respecting stratovolcano has at least one collapse to its name. They are probably a more frequent hazard than VEI6 eruptions. Consider this, since the 18th Century we have seen Unzen, Papandayan, Augustine, Ritter, Bandai, Bezhymianny (sp?), St Helens and Casita. At least. With major fatalities from five of that eight.


    • True, one would have thought that flank collapses should always have been regarded a common occurrence, especially in stratovolcanoes with their layers of different densities, and the more so in ocean settings where additionally the interaction with sea water and heat plays a big role. Perhaps, before the dawn of computers and modelling, the process just couldn’t be pictured convincing enough to generate great interest. Analog to the way it was for tsunami research, as Ward and Day describe on their website: “With accelerating increases in sonar technologies, scientists began spotting undersea landslides everywhere – in submarine canyons, on continental slopes, adjacent to seamounts, and off the flanks of oceanic volcanoes. […] With the recognition of abundant landslides underwater, recognition of their tsunami hazard followed. Folks living near shorelines that never faced risk of quake-generated waves suddenly found themselves exposed.”
      Thanks for your kind words, and Happy New Year to you!


  3. I had missed this: An image Oystein L. Andersen posted on his twitter account on Dec. 17 showed incandescence in Bromo’s crater. That’s something one doesn’t see very often, be it that the webcams are not sensitive enough or that in general nobody scrambles about in the dark caldera at nights just to take photos. I thought that Bromo had just phreatic activity in its recent episodes.


  4. Scott Kelly caught Mount Okmok Cleveland in the act letting up steam tonight! Posted 02/01 11.30 UTC on twitter, great shot!


      • According to AVO the only Aleutian volcanoes currently showing ‘significant unrest’ are the Usual Suspects, ie Cleveland and Shishaldin. If that’s a steam plume and not weather clouds that would count as unrest in my book…


      • Oops, my apologies, of course you’re right! That shows you how quickly a rumor can be created – it was late last night, it was a re-tweet and I did not check on the original tweet. It was labelled there: “Aleutian island volcano letting off a little steam after the new year”. So, Cleveland it is!


  5. The first Indonesian volcano to get an alert level rise in 2016 is G. SOPUTAN, Sulawesi; it has been set (again) to AL III (its previous eruption began in Dec. 2014 and was at AL III for 6 months). Soputan is one of the busiest volcanoes, has a growing lava dome which can spill over the crater causing lavaflows and frequent PFs and it often shows strong strombolian eruptions. Also see Culture Volcan’s blog post about it: http://laculturevolcan.blogspot.fr/2016/01/depart-deruption-sur-le-volcan-soputan.html


    In Japan, another investigation has been made into the hightened seismic activity of Mount Io (iōzan, lit. “Sulphur Mountain”), Kyushu. It is at the NW corner of the Kirishima volcanic complex in the Ebino Plateau, a tourist destination. Although there have been episodes of volcanic tremor, no increase in fumarolic acticity or ground temperature has been observed. See the report (in japanese): http://www.data.jma.go.jp/svd/vois/data/tokyo/STOCK/monthly_v-act_doc/fukuoka/16m01/20160103_505.pdf

    Finally, Volcan Fuego in Guatemala has had strong eruptions and lava flows during the past three days.
    Outstanding time-lapse video by Ricky Lopez Bruni Cine (thanks, Sherine!)


  6. Soputan eruption this morning, Plume went up to 6500m. Kindly provided by Devy Kamil Syahbana:


  7. Pingback: Pago and the Witori Caldera, PNG |

  8. Pingback: The Dakataua Caldera and Crater Lake, PNG |

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