Monday, December 6, 2010

Something on Landslides, a city known for its theatre and Insurance.

For long, the Mount road, the arterial road of Chennai was famous for the cinema theatres that were housed.  From Shanti, Devi complex, Alankar, Anand – it had more in the bylanes and for a few decades,  gathering at cine theatres was the only avocation of the city breds.   Then there is this  city of ……. also known for its extravagance, especially for the opera houses, more specifically the Teatro Amazonas which was built at a time when rubber boom was raining in fortunes.  The proposal was to build a jewel in the heart of Amazonian forest and make the land a great centre.   It began in 1881.  Roofing tiles, furnishings, marble, steel walls were all brought from different places.  It is stated that this theatre has 198   chandeliers, including 32 of Murano glass. The curtain, with its painting the "Meeting of the Waters" was originally created in Paris by Crispim do Amaral, depicts the junction of the Rio Negro and the Solimões to form the Amazon.   The dome outside is covered decorated ceramic tiles painted in the colours of national flag.    This city was at the centre of rubber boom in 19th century.  

This is a not a story of the cinema theatre but of devastation to that city brought about by a natural calamity recently.  If you had guessed the country by now, great – it is Manaus.  Today, there are reports of Colombia lying shattered and dozens are feared to have been buried in the city of Medellin due to landslide.  This region – Colombian Andes is prone to such disaster and hundreds have been killed this year.   In October this year, Manaus Port was in news due to the devastation caused by a landslide.  

Manaus a city of Brazil,  is located on the left bank of Rio Negro far, 13 km from the confluence with the River, the Port of Manaus is the main entrance to the state of Amazonas.  It geographically lies at the confluence of the Negro and Amazon rivers.  The Port of Manaus is a riverport located on the Rio Negro.  This port is the main transport hub for entire upper Amazon basin with exports of hides and leather.  

The city thrived on rubber business.  The flourishing   business of rubber ended when it was smuggled out of Amazon region, ending the monopoly enjoyed by Brazil.  The boom had ushered in electricity much before many other European cities had.   Years later the economic prosperity returned with the declaration of a duty free zone in Manaus in 1950s.

River Amazon is the largest river with total discharge greater than the next ten largest rivers combined.  At some places, its width is 1.6 and elsewhere it is even 10 kms and expands even up to 48 km when in spates and is also known as river sea due to its vastness.   It is also the second longest river next only to Nile.  The other river Rio Negro is the largest tributary to Amazon and is known as blackwater river.  Rio negro forms part of international boundary between Colombia and Venezuela.    The modern day Manaus houses several manufacturing plants including many mobile units.  

During October torrential flows of the mud swept through the riverside container terminal and two port workers were confirmed missing.  There were reports that more no. had been swept to death.   A 300-metre crack occurred along the length of the privately owned river terminal as large areas of the terminal patio gave way and crumbled into the river during the disaster, with containers, chassis and port equipment were also swept away.

The Standard Fire and Special Perils Policy covers the perils of “Subsidence and Landslide including rockslide”.  Sometimes, buildings caving in under their own weight possibly due to improper foundation  are also sought to be claimed under this head.  

Subsidence is the motion of a surface (usually, the Earth's surface) as it shifts downward relative to a datum such as sea-level.  A landslide or landslip is a geological phenomenon which includes a wide range of ground movement, such as rock falls, deep failure of slopes and shallow debris flows, which can occur in offshore, coastal and onshore environments. Although the action of gravity is the primary driving force for a landslide to occur, there  could be  other contributing factors affecting the original slope stability.

Landslides generally occur in terrain due to the conditions of soil, moisture, and slope.  Landslide redistributes soil and sediments in a process that can be abrupt collapses or in slow gradual slides.  There could be mud flows, debris flows, earth failures, slope failures etc.,  There could be natural causes such as these as also human made causes such as grading, terrain cutting and filling, excessive development etc.,  Landslides could also be classified as : fall by undercutting, fall by toppling, slump, glide, rockslide, earthflow, rockslide that develops into rock avalanche.  

At every step Nature does good things to Mankind but also makes him realize quite often that when it unleashes its power, it could be too devastating


Regards – S Sampathkumar.

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