Cairo.jpg When thinking of Natural Disasters, there are a select few that stick out to people the most; earthquakes, hurricanes, tsunamis, etc. mainly because they are the most common and they cause the most deaths and destruction. A very dangerous natural disaster that doesn’t occur very often, but is equally as destructive as an earthquake or tornado is a rockfall. A rockfall is a natural, downward motion, of a disconnected block or bundles of blocks with a small volume involving sliding, rolling, bouncing, and free falling. They can be caused naturally,by earthquakes, or by man made equipment such as sewage systems.

In September 2008, in Cairo, Egypt, a rockfall occurred and left a town extremely damaged and caused the deaths of approximately fifty people. The town affected was one of Cairo's most densely populated yet poorest areas and left more than 100,000 people homeless. Help, such as sending bulldozers was sent to remove the heavy bundles of rock covering the town. However, rocks weighing up to two hundred tons were too heavy to be lifted by the bulldozers therefore they were left with the challenge of cutting the rocks apart. Although not as prominent as earthquakes or tornadoes, rockfalls have proved to be just as deadly.

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To supplement for the amount of destruction and the immediate need for help, tents were set up for the several hundred families that survived the disaster. The cliff, part of the Muqattam Hills, is near the city of Cairo on the eastern side. Rockfalls have been frequent in the area and the authorities had movetd some people to new houses elsewhere for there own safety.
Egyptian media reported that the government had warned the town by offering them alternate housing. Although this was the help the town needed, the people felt it was merely a bribe from the government to move them from the area by guaranteeing homes that did not exist. The town was not warned with extreme urgency, so the Egyptian Government belittled their own reputation and credibility by not showing the type of concern that the city needed. They took their time sending aid and by not setting up many rescue centers, the people of Cairo are angry at their government. If the Egyptian government had taken proper precautions and took action to plead with the people of this town and updated them with the position of the rocks, it could have been a difference, and the people of the town could have been evacuated before the rockfall occurred. A proper warning system like they have for incoming tornadoes that the townspeople could identify to seek shelter could have saved lives as well. There were measures taken by the government to help those that were urged to evacuate, but considering the state of this poor town, it is clear that communication was not completely clear from government to the citizens. For example, there was a tent set up several miles away from the site of the rockfall in a garden to house the people affected, but many people claimed to have slept in the streets. Some people accused the government of making bribes in order to obtain another house, which shows no trust in the government. In most places, a government is set up to be a protector and leader of the citizens, but in a lace such as Cairo, it is difficult for the people to trust in their government. Unfortunately, this distrust led to many deaths that could have potentially been avoided.
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Figure 3

Many people were reported to be buried under the massive boulders and trapped within their homes. Unfortunately it was almost 30 hours after the fall before heavy moving equipment such as bulldozers, loaders, and cranes reached the site. And even when the heavy equipment was brought in, hopes of rescuing people trapped underneath the rocks faded, as it would still take many hours and even days before the rubble was broken up and removed. In figure 3, many people are seen standing on some the giant rocks that had fallen, either looking for those who may be trapped or trying to figure out how to deal with the current crisis.

The rock-fall that flattened a densely populated town Cairo has said to have claimed the lives of about 47 people. Boulders weighing hundreds of tons tumbled down Mungattam hill nearly wiping out one of Cairo’s poorest areas. The event of the rock-fall may have been due to leaks coming from an improvised sewage system that over time eroded away the limestone mountain. Another theory pointed towards the disaster being due to construction work on the top of Mugattam hill.


To give more information on rockfalls and the reason they occur, sources from CSA Illumina state, "Fragmental rockfall is characterized by the independent movement of individual rock fragments after detachment from a rock face. The continued operation of the process leads to the accumulation of talus slopes. On talus slopes the rockfall shadow extends beyond the base of the talus and consists of scattered boulders that have run out beyond the base of the slope." Being the more natural cause for the rockfall, geologists believe that this may have not been the exact reason or the the Egyptian rockfall. The rocks that fell over are made out of clay and limestone. The building of the new sewage system and water leaking onto the rocks, left for them to melt and fall over.

All natural disaster are not exactly caused naturally such as this rockfall. There are ways to prevent rockfalls or landslides,by taking note of their creeping for example. I believe the answer is a coincidence of geology and climate. Geology provides a strong rock with a simple joint set in which the spaces between the joints are large. This allows rare detachments of very large blocks. If the rock was weaker or more closely jointed then the blocks that fall off would be smaller, for example there would be more falls, each of a lower volume. The climate element comes from the aridity, which means that failure is not triggered by the pore pressure effects seen elsewhere. An additional factor is probably that the dry climate means that the rate of weathering is low. So a wetter climate would probably trigger more failures, each of a smaller volume. With this information research to conclude the actual result of the rockfall is being done and the fight for government aid continues.

For a more detailed view on the disaster the link provided leads to a video reporting the tragedyCairo Rockfall


References


1. http://news.bbc.co.uk/2/hi/middle_east/7607898.stm
2. http://www.reliefweb.int/rw/rwb.nsf/db900SID/FBUO-7JTCXB?OpenDocument&rc=1&emid=LS-2008-000153-EGY
3. http://www.youtube.com/watch?v=LoW74miz5HY
4. http://www.csa.com/
5. http://www.reuters.com/article/latestCrisis/idUSL7558724
6. http://en.epochtimes.com/n2/world/workers-clear-path-to-access-cairo-rock-fall-site-3963.html

Contribution:
http://www.afrol.com/articles/30695 "Cairo Rock-Fall Death up to 47"