Transcript Nevado del Ruiz! - Think Geography

Nevado del Ruiz!
By Laura Clarke 10AA
Contents!
• About Nevado del Ruiz before the
eruption.
• The impact of the eruption.
• Pictures.
About Nevado del Ruiz before the
eruption
•
Located in the Andes mountains of South America, Nevado del
Ruiz is the northernmost and highest Colombian volcano with
historical activity. With a summit elevation of 5,389 m, the volcano is
covered with 25 km2 of snow and ice even though it's located only
500 km from Earth's equator.
•
Beginning in November 1984, the volcano began showing clear signs
of unrest, including earthquakes, increased fumarolic activity from
the summit crater, and small phreatic explosions.
The Impact of the eruption
•
•
An explosive eruption from Ruiz's summit crater on November 13, 1985, at 9:08 p.m.
generated an eruption column and sent a series of pyroclastic flows and surges across
the volcano's broad ice-covered summit. Within minutes, pumice and ash began to fall to
the northeast along with heavy rain that had started earlier in the day. The crater was
enlarged slightly by the eruption, and the summit area was quickly covered with layers of
pyroclastic flow deposits as thick as 8 m. This eruption was preceded by a strong
phreatic (steam) explosion from the crater at 3:05 p.m. In this view, the dark pyroclasticflow deposits are partly covered with fresh snow.
Accounts from survivors indicate Armero was inundated with several pulses of flowing
material. The first arrived at 11:25 p.m. and consisted of a flood of cold relatively clean
water that overflowed the Río Lagunillas channel, sweeping into downtown Armero.
Only a few centimetres deep in town, this water was from a lake located just upstream
that had been displaced when lahars entered the lake. The second pulse arrived at 11:35
p.m. This was the largest pulse and within 10 to 20 minutes, destroyed most of the
buildings and swept away most of the people in Armero. Flow depths of the lahar ranged
from 2 to 5 m.The third pulse arrived at 11:50 p.m. with a velocity of about half of the
second one. Then, in the next hour or so, a series of smaller pulses (6 to 8) was
experienced by survivors trapped in the mud. These pulses lifted people floating in the
mud and pushed them a few meters ahead. One last pulse struck Armero a short time
after 1 a.m. on November 14
Hope you
enjoyed my
presentation!
Mr Manson says
• Some good information but you pack all
the writing onto one page and pack all the
pictures onto another and I think this
would have been better if the pictures
were bigger and the writing spread over a
couple more slides.
• Otherwise some good effort and content.
• A3