1. Natural Hazards Case Studies

2. One Tectonic hazard event in an LEDC
Nevado Del Ruiz, Colombia

3. Nevado Del Ruiz
Nevado del Ruiz is the northernmost of several Colombian stratovolcanoes in the Andes Volcanic Chain of western South America. The Andean volcanic belt is generated by the eastward subduction of the Nazca oceanic plate beneath the South American continental plate. Typically, such stratovolcanoes generate explosive Plinian eruptions with associated pyroclastic flows that can melt snow and glaciers near the summit, thus producing devastating lahars.

4. Key terms
Plinian – volcanic eruption with columns of gas and volcanic ash
Stratovolcano – also known as a
Conical volcano
Pyroclastic flow
Fast flowing hot
Gas and rock
Lahar – mudflow made of pyroclastic flow and water

5. Nevado Del Ruiz
After nearly a year of minor earthquakes and steam explosions from Nevado del Ruiz, the volcano exploded violently on November 13, The initial blast began at 3:06 p.m., and two hours later pumice fragments and ash were showering down on Armero. However, the citizens of Amero remained calm. They were placated by reassuring messages from the mayor over radio, and from a local priest over the church public address system. Nevertheless, the Red Cross ordered an evacuation of the town at 7:00 p.m. However, shortly after the evacuation order the ash stopped falling and the evacuation was called off.
At 9:08 p.m., just as calm was being restored, molten rock began to erupt from the summit crater for the first time (all previous eruptions were steam explosions). The violent ejection of this molten rock generated hot pyroclastic flows and airfall tephra that began to melt the summit ice cap. Unfortunately, a storm obscured the summit area so that most citizens were unaware of the pyroclastic eruption. Meltwater quickly mixed with the erupting pyroclastic fragments to generate a series of hot lahars. One lahar flowed down the River Cauca, submerging the village Chinchina and killing 1,927 people. Other lahars followed the paths of the 1595 and mudflows. Traveling at 50 kilometers per hour, the largest of these burst through an upstream damn on the River Lagunillas and reached Armero two hours after the eruption began. Most of the town was swept away or buried in only a few short minutes, killing three quarters of the townspeople.

6. Eye witness account
"We didn't hear any kind of alarm, even when the ash was falling and we were in the hotel we turned on the radio The mayor was talking and he said not to worry, that it was a rain of ash, that they had not reported anything from the Nevado, and to stay calm in our houses. There was a local radio station and we were listening to it, when suddenly it went off the air about fifteen seconds later, the electric power went out and that's when we started hearing the noise in the air, like something toppling, falling, and we didn't hear anything else, no alarm The priest from Armero had supposedly spoken on a loudspeaker [around 6:00 p.m.] and had said the same thing: that there was no need to leave Armero When we went out, the cars were swaying and running people down there was total darkness, the only light was provided by cars we were running and were about to reach the corner when a river of water came down the streets we turned around screaming, towards the hotel, because the waters were already dragging beds along, overturning cars, sweeping people away we went back to the hotel, a three-story building with a terrace, built of cement and very sturdy Suddenly, I heard bangs, and looking towards the rear of the hotel I saw something like foam, coming down out of the darkness It was a wall of mud approaching the hotel, and sure enough, it crashed against the rear of the hotel and started crushing walls And then the ceiling slab fractured and the entire building was destroyed and broken into pieces. Since the building was made of cement, I thought that it would resist, but the boulder-filled mud was coming in such an overwhelming way, like a wall of tractors, razing the city, razing everything Then the university bus, that was in a parking lot next to the hotel, was higher than us on a wave of mud and on fire, and it exploded, so I covered my face, thinking this is where I die a horrible death There was a little girl who I thought was decapitated, but her head was buried in the mud A lady told me, 'look, that girl moved a leg'. Then I moved toward her and my legs sank into the mud, which was hot but not burning, and I started to get the little girl out, but when I saw her hair was caught, that seemed to me the most unfair thing in the whole world." -- from A. Scarth (1999)

11. One Tectonic hazard event in an MED
Mount Etna 2002

12. Mt Etna
Mt Etna Volcano is one of the world's most active volcanoes. It has been erupting since several million years. Mt Etna is one of the greatest and beautiful volcano adventure tour destinations in Sicily, beside many other which can be easily enjoyed from our charming village of Taormina. This volcano has more than 400 craters, split all over the Catania county. To the ancient Greeks, Mount Etna was the realm of Vulcan, god of fire, and the home of the one-eyed monster known as the Cyclops. Etna offers skiing in the Winter months and breathtaking hikes in the woods during the Summer. There are also a number of smaller peaks on the slopes of Etna, and some interesting caverns. Since Etna is a strato volcano, with relatively cool lava temperatures and numerous openings (vents), nobody ever knows precisely where on its vast surface the next eruption will be.

17. Group 5
Mt Etna

18. A rift had began to open and the volcano looked dangerous again after a few hours various craters opened between 2700 and 2200m.s.l.m.long the rift on the western side of the volcano

19. The Facts
On 29th of October on the fracture towards valley along the North- east rift, twelve craters approximately between mt. from which emitted a Strombolian type intensive explosive activity. The following day earthquake of 3-4 on the Richter scale, seriously damaged many villages in the eastern area of Etna

20. Pictures

21. Mt Etna
An October 2002 eruption of Mount Etna, a volcano on the Italian island of Sicily, as seen from the International Space Station. Etna is the largest of Italy’s three active volcanoes and one of the most active in the world. This eruption, one of Etna’s most vigorous in years, was triggered by a series of earthquakes. Ash fall was reported as far away as Libya, 600 km (373 mi) to the south.

22. What were the primary and secondary effects of the eruption
Eruption of Mt Etna in 2002
Where is Mt Etna? (map)
What were the primary and secondary effects of the eruption
What causes Mt Etna to erupt?
How to people respond to the eruptions of Mt Etna?
Why do people live near Etna?

23. One Climatic hazard event in an LEDC
Cyclone Nargis, Myanmar 2008

24. Distribution of tropical storms
Cyclone Nargis

30. Inside Burma after the cyclone
Watch the video link and write 5 statements of what you feel about the cyclone in Myanmar

31. Cyclone Nargis, Myanmar 2008 Where is Myanmar? (map)
How did people respond to Cyclone Nargis?
Characteristics of Myanmar
What were the social and economic effects of Nargis?
What was the environmental damage of Cyclone Nargis?

32. One Climatic hazard event in an MED
Hurricane Katrina 2005

42. Distribution of tropical storms
Hurricane Katrina

43. Hurricane Katrina General information
Effects of the hurricane on people and economy
Reasons why response was so poor