Landslides in Messina, Sicily

italy_map.png

IntroductionA mudslide is the most rapid and fluid type of downhill wasting. It is a rapid movement of a large mass of mud formed from loose soil and water. Heavy rainfall, snowmelt, or high levels of ground water flowing through cracked bedrock may trigger a movement of soil or sediments. Some mudflows can be viscous and are therefore slow while others begin very quick and continue like an avalanche. Annually, landslides in the United States cause about $3.5 billion in damage, and kill on average 25 – 50 people. Landslides can often be more deadly and damaging than the original triggering event because of its force. If large enough they can devastate entire villages and country sides.
Rome Declared a State of Emergency
The Rome government declared a state of emergency recently in Messina, a busy seaport town on the island of Sicily. On October 1st, 2009 deadly mudslides caused major destruction, in what is called the worst natural disaster since the 1998 Naples mudslides that killed 150 people. Rivers of mud were unleashed by heavy rains and flooded the a large percentage of the city (see figure 1). Messina, which sits on the Northeast part of Sicily and is surrounded by cliffs and hills, experienced violent mudslides that were caused by torrential rainfall and thunderstorms. It was a disaster zone as the mudslides brought scenes of destruction throughout the town. 300 mm, 12 inches, of rain fell in a short amount of time, sparking these widespread floods. Roads, rail lines and buildings were submerged in water and engulfed by rocks and trees. The worst hit areas were the mountain villages Giampilieri and Briga, where homes and cars were swept away. Many people were driven from their homes as mudslides engulfed their neighborhoods and over 700 people were left homeless. The disaster took the lives of over 20 people and another 40 people were hospitalized. Many people lost their lives as buildings and homes toppled over. With little warning time several civilians suffocated in the mud because they did not have time to scramble out of their cars before a wall of mud struck them and swamped entire streets (see figure 2). In some places the mud was 25 ft deep. The Civil protection teams, firefighters, four sniffer dog units, and more than 200 volunteers were searching through the devastated area. As rescuers began searching for missing people, their efforts were hampered by the fact that roads and rail lines were cut off. Helicopters flew in food and supplies to the many stranded victims. Survivors were taken out of the area by sea or rescued from rooftops by helicopters. After visiting areas struck by the deadly mudslides, Italy’s Prime Minister promised to build new homes for the hundreds of people left homeless. The civil protection department for emergency relief provided 30 million dollars in addition to 30 million that was already provided by the Sicily regional government.
Figure 1- Italian Prime Minister Silvio Berlusconi visited landslide survivors in Sicily daryllorettecafe.typepad.commessina_landslides_2.jpg

Figure 2- The Wall of Mud Swamped entire streets.daryllorettecafe.typepad.comMessina_Landslides_1.jpg


To understand what causes landslides, you must understand what landslides are:


What are landslides?

Landslides are rock, earth, or debris flows on slopes due to gravity. They can occur on any terrain given the right conditions of soil, moisture, and the angle of slope. The process can either be an abrupt collapse or a slow gradual slide. The majority of mass movements happen in mountainous areas within less developed countries. Climate change, population pressure, and increased road construction can contribute to mass movements worldwide as well as gravity, earthquakes, volcanic eruptions, major rainstorms, and human made causes. In typical landslides the center of the mass moves outward and downward. The ability of a slop to resist sliding depends on the driving force pulling it down versus the friction holding it in place. Slope failure can occur when you increase the load of the slope, increase the angle of the slope, or decrease the strength of the slope.

Areas Prone to Landslides:

  • on existing landslides, old or recent
  • on or at the base or top of slopes
  • in or at the base of minor drainage hollows
  • at the base or top of a steep cut slope

Areas generally safe from Landslides:
  • on hard bedrock that has not moved in the past
  • on relatively flat-lying areas away from slopes and steep river banks
  • at the top or along the nose of ridges, set back from the top of slopes

Landslide mitigation

Vulnerability to landslide hazards depends on the location, human activity, use, and frequency of landslide events. The effects of landslides on people and structures can be decreased by avoidance of landslide hazard areas or by restricting or prohibiting building on hazard-zone activity. Local governments can reduce landslide effects through land-use policies and regulations. Individuals can reduce their exposure to hazards by educating themselves on the past hazard history of a site. They can also obtain the professional services of someone who can properly evaluate the hazard potential of a site, built or unbuilt. The hazard from landslides can be reduced by avoiding construction on steep slopes and existing landslides, or by stabilizing the slopes. Stability increases when ground water is prevented from rising in the landslide mass by covering the landslide with an impermeable surface, directing surface water away from the landslide, draining ground water away from the landslide, and minimizing surface irrigation. Slope stability is also increased when a retaining structure and/or the weight of a soil/rock berm are placed at the toe of the landslide or when mass is removed from the top of the slope.


Corruption, chronic negligence, and uncontrolled development led to and increased death toll:

The deathly mudslides that took place in Messina this past October in some ways was a very preventable disaster. The amount of water combined with the deforestation that had taken place for years contributed to the severity of the landslides. Small amounts of water will increase the cohesion of sediments but too much water eliminates grain to grain contact and allows sediment to flow like fluid (see figure 3). The amount of rain unleashed was the main cause of the mudslides that almost wiped out a whole city, but the corruption and chronic negligence of the development and buildings is the sole reason there was such a high death toll. The disaster proves the instability and 'eyes wide shut' approach to living in Italy. Messina was wiped out once before in a 1908 earthquake, yet little was ever done to repair the environment. Many of the buildings in Messina were built without proper permits and were built in dry river beds, known to be an area prone to floods. Concerns were raised and the government had warned that there was a risk of floods but there was never any action taken. Over 70% of communes in Italy have areas that are at a very high risk of disaster, yet local councils and regions ignore the danger and do very little to make the population aware. Unregulated building is common in Italy, particularly in the centre and south.

water_diagram.gif
Figure 3
-A little amount of water increases cohesion but too much water adds weight and affects the strength of minerals. source-google images


Conclusion
The rainstorm in Sicily released rivers of mud and debris that rushed down mountainsides and submerged parts of the Sicilian city, a tragedy that might have been averted if homes were not built on hillsides and the trees cut down. The long narrow Italian peninsula has mountains running through its backbone, leaving little room for cities and infrastructure. Locals blame deforestation and the Mafia's illegal building of homes and apartments to the increased death toll and although officials merely acknowledge they might have contributed, they are still blaming the rain.


Sources:
  1. www. edmontonsun.com/news/world/2009- "Corruption plus terrain equal disaster in Italy"
  2. www.italymag.uk/community/poet/landslides-messina- "Landslides in Messina"
  3. news.bbc.co.uk/2/hi/europe- "Italy mudslide Death toll rises"
  4. daryllorettecafe.typepad.com/my_cabin/2009/10/berlusconi-visits-sicily-landslides-23.htm- "Berlusconi visits Sicily after landslides kills 23"
  5. http://pubs.usgs.gov/fs/2004- "Landslides Types and Proceses"
  6. google images
7. "11 Facts about Landslides." <http://www.dosomething.org/tipsandtools/11-facts-about-landslides>