A tsunami in Miyako Japan 2011/Image credit Ibtimes.
ZIMSEC O Level Geography Notes: The effects of Earthquakes.
Factors that may affect the impact of earthquakes.
Distance of concerned area from epicenter although you should take note of the factor below.
Coastal locations have a higher risk of being inundated by a tsunami even if they are a great distance from the epicenter when the earthquake occurs at sea.
The magnitude of the earthquake, the higher up the Richter scale it is the more damage it is capable of causing.
Level of a country’s development. More economically developed countries are better equipped to predict and carry out rescue operations in the aftermath of an earthquake.
Climate of the place and time of the year can affect things like the risk of disease epidemics and risk of mudslides.
Time of day an earthquake that occurs during say rush hour can be devastating.
Relief and accessibility of the area. Mountainous regions like Nepal impede some form of rescue and relief operations.
The effects of earthquakes can be divided into shortterm and longterm effects.
Short term effects
Loss of life as people can be killed by collapsing buildings or in accidents and stampedes etc.
Homes may be destroyed leaving people homeless and exposed to the elements.
Groundshaking might lead to landslides and mudslides in wet areas and rockfalls.
Transport and other communication links such as roads can be destroyed severing vital links with the outside world and preventing aid from coming into the affected areas.
Can lead to nuclear disasters for example Fukushima-Daichii in March 2011. The long term effects of radiation are not yet fully known but may include increased cases of cancers, cataracts, deformed births etc.
Power failures which will lead to blackouts.
Water pipes can burst leading to shortages and contamination of water supply.
Shops and important business buildings may be destroyed.
Lawlessness usually comes in the aftermaths of earthquakes with widespread looting, robberies and muggings especially if the police are engaged in rescue and aid operations.
Trade, commerce and industry are disrupted.
Fires can result from gas pipe explosions.
Tsunamis can result especially in coastal areas and when earthquakes occur in the sea. Tsunamis can have waves as big as 90 meters in height, travel at speeds well in excess of 400km/hour and have waves as long as 160 km that inundate entire coastal towns causing further damage. They are generated by shockwaves that displace water in seas during earthquakes.
Long term effects
Diseases like dysentery and cholera can spread rapidly in the resulting unsanitary conditions and due to shortages of clean of water leading to further loss of life.
Expensive rebuilding exercises.
A lot of investment is diverted to go towards repairs instead of development these may severely impede a country’s development take for instance the case of Nepal whose economy has been eviscerated by repeated devastating earthquakes.
Loss of income and livelihood leading to a fall in the standards of living and an increase in general poverty.
Important landmarks and cultural landmarks can be lost.
Long term radiation effects including increased cases of cancer, deformed births and cataracts.
Further damage from aftershocks.
NB Effects can also be classified as primary i.e those resulting from the actual vibrations and shaking and secondary i.e those resulting from the after effects.
Mitigating the effects of earthquakes
Disaster preparedness practice drills so that people will know the dos and don’ts of earthquakes when it an earthquakes does occur.
Homes in affected areas should have first aid kits.
Constructing seismic activity maps so that people will be aware of risky areas.
Disaster relief operations must be carried out as soon as an earthquake occurs these should include:
The provision of clean water, medicines, water purification chemicals (tablets),
Air dropping food supplies to inaccessible areas.
Provision of tents for shelter.
Turn off gas main supply to reduce the risk of fires.
Rescue operations using earth moving equipment to rescue those trapped in collapsed buildings.
Donations towards reconstruction funds.
Building stronger and more earthquake resistant buildings can reduce the likelihood of their collapsing although no building can withstand the most devastating earthquakes.
Alternative communication methods such as shortwave radios can be used to disseminate information.
Set up disaster centers in advance.
Seismic studies can be used to try and forecast the likelihood of an earthquake occurring although this has never been known to work well as some earthquakes are, for all intents, unpredictable.