Needless to say that New Zealand is CRATER LAKE PARADISE, host of the famous “wet volcanoes” Ruapehu and White Island, and the enigmatic Lakes Taupo and Rotomahana, besides the many geothermal manifestations.

As a teaser on the full program, please check out (PDF)…

CVL10 NEW ZEALAND 1st circular

For any further questions, don’t hesitate to contact or

We hope to meet many of you on the shores of Lake Taupo in March 2019.

Welcome back Laguna Caliente

OVSICORI-UNA reports the return of Laguna Caliente, the hyper-acidic crater lake of Poás volcano, Costa Rica, as shown in the web-cam view below (top picture,

The crater lake had disappeared after culmination of the 2006-2016 phreatic eruption cycle into phreatomagmatic and magmatic eruptions, activity that started in April 2017. The southern part of the basin of Laguna Caliente (front of the top picture below) was newly formed after the 2017 magmatic eruptions that destroyed the dome, emplaced during the last major magmatic eruption cycle of 1953-1955 (lower picture).

It is no surprise that Laguna Caliente reformed, as the large volume magmatic-hydrothermal system underlying the lake was probably only temporarily and partially disturbed by the magmatic eruptions in 2017.

A recent paper by Terada and Hashimoto (2017) (Variety and sustainability of volcanic lakes: Response to subaqueous thermal activity predicted by a numerical model, J Geophys Res Solid Earth 122.doi:10.1002/2017JB14387) explains that neither a high rate of precipitation nor an impermeable layer at the lake bottom are necessary constraints to sustain/reform an active crater lake; a sufficiently high ratio between input rate at the lake bottom of a high enthalpy fluid and the lake surface can cause the re-appearance of a crater lake.

The adequate lake basin, abundant rain fall, and high fluid input from below are all factors favoring lake formation. As such, the Poás crater has returned to its most characteristic “wet” nature, hosting Laguna Caliente. The new peanut-shaped “window” into the magmatic-hydrothermal will be a useful tool for future monitoring efforts. OVSICORI and RSN-UCR will follow up the monitoring of Laguna Caliente with remote sensing techniques, direct measurements and lake and fumarole sampling, following internal safety protocols.

    Image may contain: mountain, sky, outdoor and nature               

20 January 2018 (OVSICORI web-cam:


poas febrero 15 001

April 2007 (D. Rouwet)    

The state of activity during the past year can be tracked on, or

FURTHER READING on arguably the most studied crater lake on Earth:

Recent publications on the 2006-2016 phreatic eruption cycle are:

  • de Moor JM, Aiuppa A, Pacheco J, Avard G, Kern C, Liuzzo M, Martínez M, Giudice G, Fischer TP (2016) Short-period volcanic gas precursors to phreatic eruptions: Insights from Poás Volcano, Costa Rica. Earth Planet Sci Lett 442:218-227.doi:10.1016/J.epsl.2016-02-056
  • Fischer TP, Ramírez C, Mora-Amador RA, Hilton DR, Barnes JD, Sharp ZD, de Moor JM, Barry PH, Füri E, Shaw AM (2015) Temporal variations in fumarole gas chemistry at Poás volcano, Costa Rica. J Volcanol Geotherm Res 294:56-70.doi:10.1016/j.volgeores.2015.02.002
  • Rouwet D, Mora-Amador R, Ramírez CJ, González G, Inguaggiato S (2016) Dynamic fluid recycling at Laguna Caliente (Poás, Costa Rica) before and during the 2006-ongoing phreatic eruption cuycle. Geological Society of London Special Publications 437, Geochemistry and Geophysics of Volcanic Lakes. Eds. Caudron C, Capaccioni B, Ohba T.doi:10.1144/SP437.11


Poás’ Laguna Caliente on 22 January 2018 (picture by Carlos Cordero).

LAKE SESSION: 7th International Maar Conference, Olot, Catalonia, Spain (21-25 May 2018)

I would like to draw your attention on the upcoming 7th Maar Conference in Olot, Catalonia, Spain (21-25 May 2018).

A Circular with details can be downloaded here.

The Commission on Volcanic Lakes will be represented in the Scientific Committee of the Conference, and a multi-disciplinary “lake session” will be organized:

Session 3. Lakes in maar volcanoes: the sedimentary record of paleontology, climate change and hydrochemistry

Abstract submission deadline: 15 December 2017.

We hope to meet you on the cosy town of Olot, near Barcelona, in the Garrotxa Volcanic Field, foothills of the Pyrenees.

Olot, Catalonia, Spain


Two fascinating Conferences in 2018

I would like to draw your attention on two fascinating conferences during the European spring of 2018 in Spain and Sweden. CVL aims to be present with a Scientific Sesssion. Please check here and on the specific websites of the conferences for further deadlines and details.

7th Maar Conference, Olot, Catalunya-Spain, 21-25 May 2018

Olot, Catalunya, capital of the Garrotxa Volcanic Zone.


The FIRST joint meeting of the International Paleolimnology Association and the International Association of Limnogeology, Stockholm, Sweden, 18-21 June 2018.

“Wet volcanoes” session at IAVCEI_Portland 2017


III.5 Wet volcanoes: aquifers and lakes and their related hazards

Audray Delcamp, Vrije Universiteit Brussel;
Jessica Ball, USGS;
Engielle Mae Paguican-Fabbro, Vrije Universiteit Brussel;
Benjamin van Wyk de Vries, Laboratoire Magmas et Volcans;
Dmitri Rouwet, Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Bologna, Italy;
Agnes Mazot, GNS-Wairakei, New Zealand;
Corentin Caudron, University of Cambridge, UK;
Johan C. Varekamp, Wesleyan University, USA;
Haruhisa Nakamichi, Sakurajima Volcano Research Center, Disaster Prevention Research Institute, Kyoto University, Japan;

Volcanoes store large amounts of water in their porous layers, cracks, and cavities, whereas crater lakes can be subaerial exposures of underlying hydrothermal systems or direct receptacles of volcanic gases. “Wet volcanoes” can have phreatic and magmatic eruptions, and variations in composition and temperature of the aqueous fluids, and the level of seismicity can be used to monitor such activities. Unrest at wet volcanoes often culminates into phreatic eruptions, which are generally hard to predict. The “hydrocells” themselves also pose dangers, be it limnic eruptions or rupturing of the system with toxic floods. Similarly, ground water can play a major role during collapse by changing the volcano’s rheology. Modelling the hydrogeological system of volcanic aquifers is difficult since the environment is constantly changing and geophysical data and boreholes are limited.
We invite contributions that involve studies on wet volcanoes and active crater lake systems, using water and gas chemistry or geophysical surveys, hydrogeology with focus on water storage, migration, drainage, evolution with time, and contributions on the influence of water before and during landslides. In addition, work on numerical, conceptual and analogue modeling of fluid flow as well as eruption mechanisms of these volcanoes are welcome.

Deadline for abstract submissions is March 17, 2017. Click here to start your submission.


Portland, Oregon. The Hawthorne Bridge over Willamette River (picture D. Rouwet, 2010) .


Bruce W. Christenson named CVL Secretary


Bruce W. Christenson (Senior Researcher at GNS, Lower Hutt, New Zealand) is named CVL Secretary since December 2016, after New Zealand was elected as the exciting site of the next CVL10 Workshop, March 2019. Bruce is the most active among “lake pioneers” and his work and open view on Ruapehu, Tongariro, White Island, Raoul, and other lakes on Earth, is a strong fundament for many of us. Thank you, Bruce, for taking on this important task  for CVL.

Italian lakes “flipping over” this winter

Dmitri Rouwet (INGV-Bologna, Italy) – 17/01/2017


The second lake overturn within a week at an Italian volcanic lake was recorded last weekend (14-15 January 2017).

After fish kill was observed a week earlier at Lago Averno, located in the northern sector of the restless Campi Flegrei Caldera, north of Naples, Campania, the Monticchio Piccolo lake of Vulture volcano, Basilicata, Southern Italy, turned red, while its larger, but slightly shallower (35 vs 38 m depth) neighbour Monticchio Grande maintained its usual dark blue color.



Monticchio Piccolo turned red, not-coincidently contrasting with the white snow (Pictures by Diego Sabbatini).

Despite the ongoing unrest at Campi Flegrei, also recently highlighted in the Italian and international press, Giovanni Chiodini (INGV-Bologna, Italy) explained (in a divulgation post on his Facebook page) that the fish kill at Lago Averno was caused by lake overturn due to mixing of anoxic deep water layers with O2-rich shallow water layers… no changes in volcanic activity beneath Lago Averno are needed -nor happened- to cause this at-first-eye worrying event.


Lago Averno, Campi Flegrei, Naples, during “fish-kill quiescence” (Picture by Mauro Di Vito).

Similar fish kill events occured at Lago Averno in 2002, 2003 and 2005… always during the winter period! The graph below, from Caliro et al. (2008, JVGR), explains that lake overturn, and consequently fish kill, is density driven: water density is highest at 4°C, a temperature reached for surface water only during cold winters in southern Italy. As such, the cold and dense surface waters push down into the warmer and less dense deeper waters, leading to lake overturn.


Southern Italy is currently passing through and exceptionally cold winter, with near-freezing temperatures and snowfall, even at low elevations.

The Monticchio Grande and Monticchio Piccolo lakes were formed after the 140,000 a B.P. maar-forming eruptions, the last magmatic events of the rather poorly known Vulture complex stratovolcano (1,270 m a.s.l.), in Basilicata. Lake overturn at the Monticchio lakes, as paroxysms or more gentle events, has been documented in historical reports for the past 200+ years. Some have caused fish kill, as last week at Lago Averno. Caracausi et al. (2009, Terra Nova) discuss some triggering mechanisms of these overturn events at Vulture, besides providing the dissolved gas contents along the vertical profile of the maar lakes.


A red-colored Monticchio Piccolo at Vulture volcano, Basilicata (January 2017, picture by Diego Sabbatini).

The red color of the surface waters is almost surely caused by the oxidation of iron from bottom waters transported to the surface during lake roll-over… a yet classical mechanism, adopted from the “big brothers” Lake Nyos and Lake Monoun, Cameroon.

Although unfortunate for the fish, the two 2017 lake roll-over events at Lago Averno and Monticchio Piccolo are more comforting than worrying, in terms of volcanic risk assessment: periodical turnover during winter times of lakes in temperate regions is paired with the gentle release of gas (CO2 and CH4) stored in the bottom waters (Cabassi et al. 2013, Bull Volcanol), avoiding gas pressure build-up to supersaturation levels in deep water layers, possibly leading into more explosive gas releases. Nevertheless, both Lago Averno and Monticchio Piccolo (and Grande) are a lot smaller and less deep than Lakes Nyos and Monoun (Cameroon, 1986 and 1984 lethal gas bursts), and hence cannot store large amounts of gas to eventually convert them into Italian “killer lakes”.

Further research might be needed (CTD depth profiles, chemical and isotopic composition) to detail these particular events; operations that will probably support the above hypothesis based on simple surface observations and scientific experience.

Regarding volcanic risk reduction, let’s say that re-zeroing the “CO2-CH4 clock” at these shallow lakes is rather “good” than “bad”.

With the striking of these winter lake roll-overs in southern Italy, a major concern now is to see if, and if so how, Lago Albano will “flip over ” this winter. Earlier research has demonstrated that Lago Albano, a large, 167 m deep crater lake of the active Colli Albani volcano (south of Rome) partially releases its CO2 each winter (Chiodini et al. 2010, Bull Volcanol), after being recharged with CO2 during a seismic swarm in the late 1980s.

Since the recent major tectonic earthquakes in Central Italy (August-October 2016) a depth survey has not yet been elaborated at Lago Albano.



Giovanni Chiodini and Dmitri Rouwet (INGV-Bologna) during the May 2010 Lago Albano survey.