“The Most Acidic Lake in the World (Great Volcanoes of Costa Rica)”

VOLCANOES OF THE WORLD: “The Most Acidic Lake in the World (Great Volcanoes of Costa Rica)”



Costa Rica as most of Central American and South American countries of Pacific Coast has plenty of volcanoes which are results of subduction activities of Cocos Plate – in case of Central America - and Nazca Plate in case of South America.

Even the whole country has at least 10 significant volcanoes – largest and most important are Rincon de la Vieja, Irazu and mainly then Arenal and Poas. During our second visit in Costa Rica Rincon stayed obscured by the clouds during the whole week and Irazu was closed because of eruption activities. So it was “only” Arenal and Poas which we could visit.

First about Arenal. This volcano changed my focus of interests back in 1999. During the travel around the country we stayed one night in really simple shack right by the foot of volcano. To our big surprise 11 PM came first earthquake which kept us awake for hours. Then 4 AM came second – much stronger earthquake – and finally 5 AM Arenal erupted right front of our eyes. Since I have never before seen volcano eruption in close range impression was monumental, even eruption was certainly far from to be major one.
Ever since that moment I changed my interest and hobby from Cosmology to first Volcanology and later Plate Tectonics what stayed with me until presence.
Obviously eruption in 1999 was one of the minor once for volcano which from the time of arrival of Spanish until 1960’ was considered as Extinct Volcano. Than in July 1968 after almost 500 years inactivity volcano awaked in spectacular series of eruptions which caused Pyroclastic Flows which killed 78 people in villages by the foot of the volcano. Arenal stayed active ever since and even during our second visit in Costa Rica – from which is this footage – one can see mainly fumarole activities on the top of the volcano.
Arenal with beautiful conical shape – so typical for all dangerous Stratovulcanoes – and with height of 1,657 m is one of the most active of Central American volcanoes and belong to one of the biggest attractions in Costa Rica for domestic and international tourism.

Poas Volcano is something else. It’s Stratovolcano as well but height of the mountain 2,708 m (with numerous cones and craters) in the centre of volcanic massif is in the heart of Parque Nacional Volcan Poas. Two of Poas Craters have lakes – and here the whole story start to be interesting.
The main crater – which was filmed during 2 days of dramatically different weather conditions – has diameter of 1.6 km and is more than 300 m deep. It contains one of the world’s largest volcanic lakes. Eruption activities had appeared in 20-50 years periods but most spectacular was eruption in 1988-89. During fumarole activities in this period in April 1989 the lake had been completely drained – this event led to formation of liquid sulfur lake, which is an unprecedented event on Earth!
In the same month eruption of hot mud and sulfur reaching 2 km height and kilometers from the crater forced the park to be temporary closed.
Todays crater is showing weak fumarolic activities with temperature below 100 C – BUT! – Crater Lake visible in the movie is extremely highly acidic with pH less than 1!!!
This represents Acid Lake without comparisons in the whole world.

For better feeling from the movie last shot is of the other Poas Crater Lake Botos, which is just walking distance from Main Crater “Inferno”.

Welcome to Costa Rica and enjoy!

Cheers
Jiri