Case Study

Gujarat Earthquake

• 6.9 on Richter-Scale rocked the Western Indian State of Gujarat on the 26th of January, 2001.
• Government of India figures place the death toll at 19,727 and the number of injured at 166,000. 

1. The epicenter was near the remote Little Rann of Kutch, but within 150 to 200 kilometers of several villages and towns. The proximity to populated areas, coupled with a shallow 17-kilometer focus, resulted in massive destruction and fatalities
2. The affected area also experienced magnitude 5.0 to 5.8 aftershocks for several days subsequent to the main earthquake 

DAMAGE CAUSED BY EARTHQUAKE

1. Both rail and highway traffic into and out of the entire Kachchh region was completely cut off for two days. Numerous bridges, dams, and ports were destroyed or severely damaged as a result of liquifaction of the blue marine clay soil on which they are constructed.
2. Total blackout resulted in several towns and villages; communications in Bhuj were disrupted for two days when fiber optic cables were damaged, and water supplies were affected as liquifaction caused some wells to become turbid and others tested positive for metal contaminants and anaerobic sludge .
3. Approximately 1,000,000 homes were destroyed or seriously damaged, as were many commercial, industrial, and public utility facilities.

Mitigation Plan

Before

• Enforcing building codes
• Inspection of older buildings
• Mitigation plan awareness
• Land use planning

During

• Crouch under the table
• Avoid power lines

After

• Emergency response plan
• Priority for setting place of establishment of emergency disaster management headquarter
• Priority for setting place of establishment of local emergency disaster management headquarter
• Act for maintaining business continuity for metropolitan function
• Act for emergency rescue such as rescue, aid, medical and fire-fighting activity, procurement of food and water, and securing traffic for emergency transportation

Introduction to Earthquake

WHAT IS EARTHQUAKE? (EQ)

An EQ is a sudden motion or trembling (shaking) of Earth caused by the abrupt release of energy that is stored in rocks (Thompson & Turk, 2007).

Source(s) of EQ:

• tectonic plate motion
• fault movement
• volcanic activity

1. Rock breaks and move along a fault to release strain that has gradually built up in the rock.
2. Volcanic activity

•      Tectonic forces acting deep in the earth may put a stress on the rock, which may bend or change in shape(strain).
•      If your bend a stick,your hands put a stress on the stick,its bending is the strain.

The focus of an earthquake is the point where rocks first break along a fault 

seismic waves radiate from the focus.The epicenter is the point on the Earth’

surface directly above the focus.

SEISMIC WAVES

1.        Body waves: seismic waves that travel through the Earth’s interior,spreading outward from the focus in all direction.
2.        Surface waves: seismic waves that travel on Earth’s surface away from the epicenter,like water waves spreading out from a pebble thrown into a pond.

BODY WAVES
P waves (compressional) 6–8 km/s.
Parallel to direction of movement (slinky),also called primary waves. Similar to sound
waves. 

S waves (shear) 4–5 km/s
Perpendicular to direction of movement (rope);Also called secondary waves. Result from
the shear strength of materials. Do not pass through liquid.

SURFACE WAVES

Love waves
Like S waves that have no vertical displacement.The ground move side to side in a
horizontal plane that is perpendicular to the direction the wave is propagating.

Rayleigh waves
Behave like rolling ocean waves.Unlike the ocean waves,Rayleigh waves cause the ground
to move in an elliptical path opposite to the direction the waves passes.

Destruction results form :

•       Ground shaking
•       Liquefaction of the ground
•       Flood 
•       Fire (damaging of electrical power and gas line)
•       Tsunami, or seismic sea waves
•       Landslide