Hazards, Disasters And Your Community - United Nations ...

TYPICAL EFFECTS
Physical Damage – damage or loss of buildings and service structures. Fires, floods due to dam failures,
landslides could occur.
Casualties – often high, near to the epicenter and in places where the population density is high (say,
multistoried buildings) and structures are not resistant to earthquake forces.
Partial collapse of non engineered building (stone
masonry walls) during 1991 Uttarkashi earthquake.
(Source: Earthquake Tips IITK-BMTPC)
Improperly designed weak or flexible storey leads to poor
performance during earthquakes. Many buildings with open
ground storeys intended for parking collapsed in the Bhuj
earthquake. Seen is the picture is a vertical split of a building due
to collapse of a partially open ground storey building.
(Source www.nicee.org Earthquake Tips IITK-BMTPC)
Public health – multiple fracture injuries, moderately and severely injured is the most widespread
problem, breakdown in sanitary conditions and large number of casualties could lead to epidemics.
Water supply – severe problems due to failure of the water supply distribution network and storage
reservoirs. Fire hydrants supply lines if vulnerable could hamper fire service operations.
Transport network – severely affected due to failure of roads and bridges, railway tracks, failure of airport
runways and related infrastructure.
Electricity and Communication – all links affected. Transmission towers, transponders, transformers
collapse.
MAIN MITIGATION STRATEGIES
Engineered structures (designed and built) to withstand ground shaking. Architectural and engineering
inputs put together to improve building design and construction practice. Analyze soil type before
construction and do not build structures on soft soil. To accommodate on weak soils adopt safety
measures in design. Note: Buildings built on soft soils are more likely to get damaged even if the
earthquake is not particularly strong in magnitude. Similar problem persists in the alluvial plains and
conditions across the river banks. Heavy damages are concentrated when ground is soft.
Good soil conditions
– sharp rumbling
Weak soil conditions
– violent shaking
Hypocenter
Effect of soil type on ground shaking
Essential requirements in a Masonry building
“ t o w a r d s s a f e r I N D I A ” 12