Transcript Earth Science in Costa Rica (2002)

Would you ever do this?
II did!!!
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 81*F (27*C) 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 67*F
(20*C) 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.
Before we get to Earth Science, how about a little
Costa Rican bio…..
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.
This is another plant that does not require
too many sun rays.
This tree will move a few centimeters in order to
have access to a little insolation.
Yes, it really walks!!!!!
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.
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.
After Arenal’s lava cools (solidifies) it turns into solid basalt
rock.
Massive amounts of basalt can be found miles away from the
volcano.
Lava is about 1000*C when it comes out of a crater.
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.
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.
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.
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.
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.
Irazu, the name of this
subconical volcano, derives
from an indigenous word
meaning “thunder and
earthquake mountain”.
Irazu is a strato-volcano that
towers 3,432 metres above sea
level.
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.
Remember this?
Just some good old earth science review!!!
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.
Apparently in Costa Rica, wearing volcanic ash on your
face is just like putting on insect repellant.
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.
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.