Multiple Hazards in Cities: Examples from London, Mexico City and Los Angeles

Multiple Hazards in Cities: Examples from London, Mexico City and Los Angeles

London

London has experiences a variety of hazards for a long period of time.

* Royal decree in 1306 banned burning of coal to reduce air

pollution

* The Great Fire of London which burned over 13 200 homes

* The little ice age which caused the Thames to freeze over

* The Blitz of WW2 which destroyed many homes and industry

* High tides and storm surges

* Smog, especially in the late 50's.

London is prone to storm surges due to a combination of reasons;

* Rising sea levels

* Down tilting of the south of England (isostatic uplift)

* Long-term subsidence.

Smog has occurred as a consequence of all of the pollutants pumped

into the air around London. Some of the worst were in December 1952,

when;

* Visibility was down to 5m

* Fog had a pH of 1.6

* There were nearly 4000 deaths.

To tackle this problem the following strategies were introduces;

* The 1956 clean air act banned coal fires and provided financial

assistance to households to convert to smokeless fuel

* Houses prompted to convert to oil and gas

* Legislation reducing the sulphur content of oil to 1% also helped.

As a result the pollution in London dropped dramatically and continued

Throughout the 80's.

However the smog's returned in he 90's, but rather due to industry it

was due to the large number of vehicles in London. The government

attempted to reduce he pollution levels in a number of ways;

· Variable speeds on the M25 to reduce traffic jams

· Pedestrianisation of shopping areas

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...l coverage from space

* Hazard zonation maps

* The monitoring of active volcanoes all help in managing the crisis

when it has happened.

Flooding is common in the Philippines due to tsunamis and typhoons.

Lowland floodplains can't cope with the huge amounts of water. The

result of flooding e.g. in July 1972, 600 were left dead, 370 647 were

left homeless and 200 000 ha of crop land was destroyed. This resulted

in £20 million of damage to roads, bridges and infrastructure.

Drought is also a problem as there are often several months with very

little

rainfall (up to 40% less). The last significant drought was in

December 1986 when most of the country was affected. In 1989 a drought

weakened the economy with a loss of agricultural production, just

before the 1990 earthquake and the 1991 eruption.