Earth Science in Costa Rica

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Earth Science in Costa Rica
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Would you ever do this?
II did!!!
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Costa Rica Background
Costa Rica covers 19,730 square miles (51,100
km), which is smaller than West Virginia. About
60 of Costa Rica is covered by different types
of forests. Over 11 of the land is reserved as
national parks. This small nation has a diverse
landscape of tropical rain forests, mountain
cloud forests, volcanoes, green pastures, and
beautiful rivers and beaches. Although the
country lies entirely in the tropical climate
zone, elevation changes allow for cooler
temperatures in the central highlands. The
coastal lowlands are hot and humid with
temperatures averaging 81F (27C) throughout the
year. Most people live at elevations where the
climate is generally mild. In San Jose and other
parts of the central valley highlands
temperatures average 67F (20C) year round.
Rainfall varies between the dry season
(December-April) and the wet season
(May-November). Costa Rica is also subject to
earthquakes, hurricanes and volcanic eruptions.

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Costa Rica
Capital San Jose
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Before we get to Earth Science, how about a
little Costa Rican bio..
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This plant thrives in excessive moisture and
minimal sunlight.
The floor of a rainforest does not receive much
sunlight due to the canopy of trees hanging above.
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This is another plant that does not require too
many sun rays.
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Walking Palm Tree
Walking Palm Tree
This tree will move a few centimeters in order to
have access to a little insolation. Yes, it
really walks!!!!!
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Deforestation in action
Deforestation involves the cutting down, burning,
and damaging of forests. The loss of tropical
rain forest is more profound than merely
destruction of beautiful areas. If the current
rate of deforestation continues, the world's rain
forests will vanish within 100 years-causing
unknown effects on global climate and eliminating
the majority of plant and animal species on the
planet.
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Onto the Geology
...
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The Arenal Volcano
Volcán Arenal is a stratovolcano which rises
1,657 meters above sea level and is situated in
north-western Costa Rica (10.463N, 84.703W), 90
km north-west of San José. Less than 3,000 years
old, this andesite-basalt volcano is Costa Rica's
most active. On July 29th, 1968, after
approximately 500 years quiescence, Arenal
erupted explosively killing 78 people, and has
since been continuously active. Arenal is one of
seven historically active Costa Rican volcanoes.
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After Arenals lava cools (solidifies) it turns
into solid basalt rock. Massive amounts of
basalt can be found miles away from the volcano.
Lava is about 1000C when it comes out of a
crater.
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Arenal has a volume of only 15 km3 and is the
smallest but most active of seven historically
active Costa Rican volcanoes. The tectonic
setting of the volcano is disputed, with some
authors suggesting that Arenal overlies a tear in
the subducting Cocos plate and others believing
there is a smooth transition in the orientation
of the Wadati-Benioff zone, thought to lie 150 km
below Arenal. The small truncated and dormant
volcano, Cerro Chato, lies approximately three
kilometres southeast of Arenal. Arenal is most
likely directly tapping a lower to mid-crustal
magma chamber, possibly located at a
discontinuity which lies at a depth of 22 km.
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This is Arenal Volcano viewed towards the
northwest from a small town, by tourists and
school kids. Arenal usually produces a small
explosion every few minutes larger eruptions
occasionally occur. Most of the recent activity
has occurred on the north side, away from this
particular view, so the flanks visible here are
mostly vegetated. If you look closely, however,
you can see where both lava flows and pyroclastic
flows have burned their way down the flanks.
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Arenal was a dormant stratovolcano. Young
deposits were of the slopes of the volcano but it
had not erupted in historic time. Arenal's status
changed dramatically in July of 1968. An
explosive eruption produced hot avalanches and
ejected blocks that devastated the west flank of
the volcano. Arenal has been continuously active
since 1968. This photo shows a slow moving lava
flow on the west flank of Arenal.
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Irazu Volcano
The centerpiece of this national park is the
highest active volcano in Costa Rica, Irazu, at
2,432 meters. It is because eruptions of this and
other volcanoes that the soil of the Central
Valley is so fertile. The Irazu National Park is
remarkable because of its surreal lunar
landscape.
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The Irazu Volcano has three craters. The
Principal Crater is 1050 meters in diameter and
300 meters deep. The Diego de a Haya Crater is
690 meters in diameter and 100 meters deep. It
contains a small lime-green lake.
Diego de a Haya Crater
Crater 1
Why is the crater lake green?
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Irazu, the name of this subconical volcano,
derives from an indigenous word meaning thunder
and earthquake mountain.
The Principal Crater
Crater 2
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IRAZU
Crater 3
Irazu is a strato-volcano that towers 3,432
metres above sea level.
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Volcanic Ash
When volcanoes erupt finer material is convected
upwards in an eruption column before settling out
downwind to form volcanic ash fall deposits. Ash
fall deposits are composed of various proportions
of volcanic glass, crystal or rock particles.
Volcanic glass can be glass shards or pumice
derived from magma, while crystals are minerals
developed in the magma. Different minerals
reflect the composition of different magmas.
The years following eruptions are bountiful, in
large part due to the fresh load of minerals and
trace metals delivered by the ash to the soil. 
In moderation, volcanic ash can be very
beneficial, rejuvenating soils long exploited for
crops. 
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Remember this?
Just some good old earth science review!!!
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Sometimes the soil is too moist (saturated) and
cannot support tree roots
The waterfall is created by a very resistant rock
surrounded by less resistant rock.
Boring...
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High Elevations
Clouds forming all around .
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Apparently in Costa Rica, wearing volcanic ash on
your face is just like putting on insect
repellant.
Now for the fun stuff
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VOLCANO ASSIGNMENT
Objective Students will gain a better
understanding of the United States geologic
history.
Your mission is to find information and report on
a volcano that has erupted in the last 100 years.
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Your Report Must Include

• Volcano name
• Type of volcano
• Location (city and state)
• Latitude and Longitude
• Name of nearest city
• Distance to nearest city
• Population of the city
• Other disasters caused by the eruption
  (earthquake, flood, mudslide, tsunami)

• The last page should be a speculation of what
  you would do if you were to be in charge of
  minimizing the risk to the public.