Environmental M

Earthquakes
During an earthquake the ground shakes and vibrates rapidly.
A seismograph measures the magnitude of an earthquake according to de Richter scale:
Above 4 | Above 5 | Above 6 |Everyone feels it | Some damage is caused and loss of life becomes possible | Much damage and destruction, also great loss of life |
* Nine out of every ten strong earthquakes occur at destructiveboundaries.
Focus | Epicenter |
The point of origin underground | Where it reaches the surface (where the shock is stronger) |
The shock waves decrease its strength as the distance from theepicenter increases

Effects of an earthquake
Primary effects | Secondary effects |
Are the ones caused by the shock itself. | Are the ones that happen in the minutes, hours or days after theearthquake. |
Fire is the most dangerous secondary effect in cities: broken gas pipes can cause explosions and sparks from damaged electricity cables. Water to fight fires is not available because thewater pipes will also have been broken by the earthquake. |
Disruption to water supplies increases the risks of the spread of diseases such as cholera and typhoid. The local economy can bedevastated.
Most important facts about the damage caused by earthquake:
* The amount of people living close to the epicenter
* The quality of the construction of buildings
* How well preparedthe people and emergency services are
The six earthquakes which resulted in great loss of live occurred in densely populated areas where many un the buildings where too weakly constructed to resistthe earthquake shocks. Example: in 1993 an earthquake in India with a magnitude of 6.4 killed 22,000 people.
The best strategy to prevent loss of life in earthquakes:
- Constructing buildings thatcan resist earthquakes.
- Ensuring that factories are not located next to houses (land use zoning)
-Educate people about what to do on an earthquake
* get out on an open space as soon as...