January 13: Poas

Steven Dutch, Professor Emeritus, Natural and Applied Sciences, University of Wisconsin - Green Bay

	Last fond look at the Research Station.



	Our ride awaits.

Do You Know The Way To San Jose?

	Well, uh, not as well as we thought. We got to about the nicest view point on the highway and the bus started having cooling problems.



	The distant peak is the high point of Carara National Park.


	Basalt Outcrop.





	Left: The problem turned out not to be too serious. Below: Coffee trees by the roadside.










	Turrialba, 3,340 m (10,958 ft) gave us the most convincing display of volcanic activity with this persistent steam plume. Turrialba had a number of eruptions in the 19th century and began showing increased activity in 2001.


	Volcan Barva (2906 m; 9,534 feet) is the least active of the three major volcanoes overlooking San Jose. It last erupted about 6000 BC


	Wisconsinites are used to seeing large screens like these used for growing ginseng. Here they are used for shading flowers.

	Poas is a popular outing spot and we inched our way in.

	Irazu, 3,432 metres (11,260 ft) is the peak beyond the clouds. It's the highest active volcano in Costa Rica and, apart from a steam blast in 1994, last erupted in 1963-65. The flank of Volcan Barva is in the middle distance. Unlike Hilary Clinton, John F. Kennedy really did land under fire. The 1963 eruption began the day he arrived for a state visit. Irazu has had more than 20 explosive eruptions since 1723.








	This little bowl is a former crater of Poas.


	The devegetated area is probably from eruptions in the spring and summer of 1994. Good news: we had a crystal clear day, unlike the visit in 2007 where the crater was socked in. Bad news: we missed a small steam explosion by just a couple of hours.










	Below: ejecta layers near the crater.





	The trail leads to a lake in an older crater of Poas. Increased thermal activity in the lake led to trail closure for safety.








Below: the low area is an inactive crater of Poas.






	Views of San Jose on the way down.