Costa Rica

Volcan Arenal und Murphys Law, März 2009  

By M. Rietze


Already for years a visit to Costa Rica was planned. Although no special activity was to be expected at present, I made this trip during the 3rd of March 2009 to the 23rd. During these two weeks not only volcanism was the main subject, also the flora and fauna was an interesting part in addition.



It’s known that also in the dry season the Arenal volcanic summit is often covered in rainclouds. For this reason I planned I the Arenal visit directly at the beginning. The constant wind supplies inexhaustible humidity of the Caribbean Sea, which is condensing in the higher mountain ridges. First, at the Poas volcano, rain and nebula was dominating. The friendly lady at the National Park entrance recommended to me, to return once again because the sight was by Zero. In order to make it short: This speech I heard often during the whole journey…




Driving through the beautiful La Paz area in direction to the Arenal would have been the most elegant way, but the earthquake a few weeks ago was destroying too much infrastructure. Meanwhile the Poas craters were spared out of damage, the northern flanks were badly battered. A later start from the north showed the substantial road damage and slope chute, La Paz exists any longer…


From this point there was no other choice to take the way back and detour to the Arenal area. Now there was the big question, the volcano or I. At the beginning various and rich contacts with the endemic animals living in the area was made up. A rhythm got into practice: During the day long walks and animals observation - at night waiting for hours for the clearing up at the volcano. If someone wants to give up sleeping, the Arenal offers ideal opportunity in addition.


A clearing up in the night time took place during my visit in the proportion of 1: 10000 (1 minute per week) for instance. After some days the impulse to discover different areas of this country became more intensive. After several sleepless nebula-nights I decided heading out for Rincon de la Vieja in the Monteverde rain forests. And just in the evening the whole slat again back to the Arenal for the next rain night. This volcano anyhow was after 6 (!) nights for few minutes completely visibly. However it showed thereby only a few glowing rolling lava boulders. You could hear the sporadic Strombolian activity only in twice times per night through the clouds.


Although I was close to the summit and nearly in indivisibility, I didn’t succeed top mounting. The ideal way was a forest path and then over an old gauging station through some erosion canyon. Ascending the summit slope is laborious, but unproblematic. However the weather was not too bad the incident fog in the summit region made the further ascend senseless and dangerous. During the countless night-hours during one week the following activity behaviour was showed up:


Roughly all 15min a small glow avalanche loosens itself. A few times per night a considerably large avalanche is crashing down to the vegetation border and both into the southern and western direction. Two or three times you can hear the noise of the summit during the night, accompanied possibly with a sporadic strombolian activity. All glow avalanches separate from the western situated small dome at the summit crater.

The Arenal edition of Murphy’s Law describes the happening excellently

  • summit outbreaks and larger glow avalanches take place principle only during cloud coverage

  • beginning a mounting in a clearing up weather condition the summit tightens a short time before arrival again

  • beginning a daily trip in a other national park you can see from the distance the completely free Arenal

  • driving back laboriously the entire distance under continuous sun heating, the Arenal surely draws up again in rain clouds in the afternoon.

  • if you break off the night monitoring due to tiredness and endless insect bites, it begins to clear up

  • when it's clearing up you break off the provisional night rest again

  • if you stopp your night rest, the highest summit point nevertheless remains in a nebula flag

  • when its clearing up again suddenly extreme humidity is existing, which tarnish the optics

  • if you wipe off the tarnish to take a picture of the summit flag it will surely fail because of the weak accu induced by the eternal test shots

  • if it is passably clear, the next glow avalanche is missing

  • when the summit steps again into a dense cloudy appearance, an unusual violent glowing avalanche takes place

  • if you return the next night back again with the opinion, it can’t get not more worse, it draws up finally to a continuous rain

Result: hopefully the activity of this volcano does not increase sometimes again, because then the drama begins again. 



 -translation under construction-

Beim Besuch des Rincon de la Vieja Vulkan lohnt sich eine Gipfelbesteigung wegen des interessanten Kratersees und eine Wanderung durch das im Wald gelegene Thermalgebiet an seinem Fuß. Auch ?hier schlug wieder die Gipfelwolke zu. Schönstes Wetter weit und breit, jedoch Regen, Wind und Nebel am Gipfelkrater. Fünf Stunden Warten wurden mit 2,5s nebeligem Seeblick belohnt, siehe Bild.


Das gleiche Spiel wie eingangs angedeutet am Poas Krater, nur eine kurze Aufklarung vor Sonnenuntergang erlaubte einen freien Blick.


Bei den höheren Vulkanen Irazu und Turrialba bleibt die Wolke oft unterhalb, daher herrschen hier morgens oft gute Bedingungen.
Im Gegensatz zum überlaufenen Irazu mit seinem Kratersee bietet der Turrialba noch unberührten Nebelwald. Auch der Quetzal ist hier einfach zu beobachten. Die dortige Lodge, Wanderungen und Allradfahrzeugerlebnisse in diesem urigen Gebiet und ein Sonnenaufgang an den Gipfelfumarolen Fumarolen ließen diesen Vulkan mit Abstand zum schönsten Landschaftserlebnis dieser Reise werden.



Als Kontrast bieten sich zwischendurch die nahe gelegenen Küsten an. Aus zeitlichen Gründen (Arenalduell...) blieb nur Zeit für die Pazifikküste. Aber schon hier beeindruckt die für Europäer fremdartige Tierwelt ungemein, bei Rundgängen oder Bootsfahrten kommt man ständig neues hautnah zu sehen.



Abschließend kann man Costa Rica jedem Tier- und Pflanzenfreund wirklich empfehlen. Die vulkanische Aktivität ist derzeit recht gering, alle besuchten Vulkane haben aber eine bewegte Geschichte und sind jederzeit zu starker Aktivität fähig.


Jump to Dec.2007

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©2009 Photos und Text by M.Rietze, last modification 05.09.2009

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