earthquake reality and basic safety tips

Comprehensive Disaster Management Programme (CDMP II) Ministry of Disaster Management & Relief

Earthquake Reality and Basic Safety Tips

June, 2015


ANCIENT EARTH


EARTH STRUCTURE

The core composed of melted iron and nickel.

The mantle is melted rock.

The crust is solid rock.

Heat currents travel from the core through the mantle to the crust.

They travel horizontally under the crust.


TECTONIC PLATES OF THE EARTH

The earth’s surface consists of tectonic plates.

There are 9 larger and 12 smaller tectonic plates.

Magma moves plates looking for a weaker place.


TECTONIC PLATE MOVEMENT

A plate collides with or dives under another (Himalayas)

Magma rises and pushes plates apart

Two plates slide pass each other


THE ALPINE-HIMALAYAN stretches from Spain to New Zealand


INDIAN PLATE

EURASIA PLATE

BURMA

PLATE

PLATE AND FAULT

In and around Bangladesh

Dauki Fault

Act

ive

Su

bd

uct

ion

Zo

ne


EQ HISTORY OF THE REGION

2015


EQ HAZARD MAP OF BD


MAJOR EARTHQUAKES AFFECTING BD

Date Name of Earthquake

Magnitude

(Richter)

Intensity, Dhaka (EMS)

Distance from Dhaka

(km)

10 January, 1869 Cachar EQ 7.5 V 250

14 July, 1885 Manikganj /Bogra EQ

7.0 VII 60/170 (?)

12 June, 1897 Great Indian EQ 8.7* VIII+ 230

8 July, 1918 Srimongal EQ 7.6 VI 150

2 July, 1930 Dhubri EQ 7.1 V+ 250


TIME PREDICTABLE MODEL

Segment Events Recur. Per. (years)

Elap. Time (years)

50 year Prob. T-Depen. (%)

Est. Mag. (Mw)

Length (km)

PBF-1 AD 1762 1) AD 680 to 980 1)

BC 150 to AD 60 1). 2) BC 1395 to 740 1)

900 246 1.1 8.5 795

PBF-2 Before 16th century > 900 > 508 > 6.7 8.0 270

PBF-3 Before 16th century > 900 > 508 > 6.7 8.3 504

Dauki Fault (DF) AD 1897 3) AD 1500 to 1630 3)

(AD 1548 ?)

349 111 7.0 8.0 233

Madhupur Blind Fault (MF)

AD 1885 350 123 8.7 7.54) 60

Non-characteristic but relating to fault 5) (PBF-2, PBF-3, DF)

AD 1918 (PBF-2) AD1869, 1943, 1954,

1988 (PBF-3) AD 1664, 1923, 1930 (DF)

20 - - 7.0 - 7.5 -


BUILDING INVENTORY FOR SEISMIC VULNERABILITY ASSESSMENT

Dhaka : 326,825 Chittagong : 185,000 Sylhet : 52,000


WHAT CAUSES AN EARTHQUAKE?

Movements of tectonic plates cause stress and energy to build up. When stress exceeds, the earth’s surface cracks and releases energy

causing earthquakes. Can be caused by nuclear tests, etc.


SEISMIC WAVES

M=1

M=1

M=1

M=2

M=2

M=2

Body W

ave

Seismogram


MEASURING EARTHQUAKE

2 ways of measuring size of an earthquake:

– Magnitude: amount of energy released - "Small earthquakes make small waves, big earthquakes make big waves"

– Intensity: amount of damage, reaction of people (Modified Mercalli Intensity Scale)


MEASURING EARTHQUAKE Magnitude Intensity Effects

< 3.4 I Recorded only by seismograph

3.5-4.2 II & III Felt indoors by some

4.3-4.8 IV Felt indoors by many

4.9-5.4 V Felt indoors by all

5.5-6.1 VI and VII Slight building damage

6.2-6.9 VIII and IX Much building damage

7.0-7.3 X Serious structural damage

7.4-7.9 XI Great, widespread damage. Few masonry structures remain standing. Bridges destroyed. Rails bent greatly.

>8.0 XII You don’t want to know. Total destruction. Lines of sight and level are distorted. Objects thrown into the air.

8.8 Chile – 27/02/2010

9.4 Aceh – 26/12/2004


4.0+

Windows may break, unstable objects fall


5.0+

Furniture moves, chunks of plaster fall, walls may crack


6.0+

Damage to strong houses, collapse of unstable ones


7.0+

Buildings displaced, cracks in the earth


EARTHQUAKE IMPACT

Direct effects

o Ground failures or instabilities due to ground failures

Surface faulting or fault rupture

Vibration of soil (or effects of seismic waves)

Ground cracking

Liquefaction

Ground lurching

Differential settlement

Lateral spreading

Landslide

o Vibrations transmitted from the ground to the structure

Indirect effects

o Consequential phenomena

Causes most damage!


Surface faulting

Liquefaction

Kawagishi-Cho, Niigata, Japan Turnagain, Anchorage, Alaska

Beni Rached, Algeria

Argentina El Salvador

Landslide Fire

Kobe, Japan

Tsunami

Japan


BEFORE THE NEXT EARTHQUAKE PREPARE

Create a family EQ plan

Know the safe spots in each room

Know the danger spots

Decide where your family will reunite if separated

Keep a list of emergency phone numbers

Develop a survival kit for work, car, and home

Secure heavy furnishings

Learn how to shut off gas, water, and electricity

Check foundations for stability

Secure water heater and appliances

Keep heavy objects on lower shelves

Maintain emergency food, water, medicine, first aid kit, tools, and clothing


DURING THE NEXT EARTHQUAKE INDOOR

Stay away from windows, bookcases, file cabinets, heavy mirrors, and other heavy objects that could fall

Duck under a desk or sturdy table

Watch for falling plaster or ceiling tiles

Stay undercover until the shaking stops, and hold onto your cover

If the desk or table you are under moves… move with it

Don’t forget about aftershocks


DROP to the ground

COVER Take cover until the shaking stops

HOLD onto whatever you are underneath. If it moves then move with it



WHAT ARE SAFE PLACES …

indoors

outdoors???

Google Map/Strret View


DURING EQ: SPECIAL SITUATIONS

Outdoors - Move to a clear area, away from trees, signs, buildings, or fallen electrical wires & poles

Near buildings - Move into a doorway to protect yourself from falling bricks, glass, plaster & other debris

Driving - Pull over to the side of the road and stop. Avoid overpasses, bridges, power lines, & other hazards.

Crowded store or other public place - Do not rush for the exits. Move away from display shelves with objects that could fall

High rise building - If not near a desk or table then move against an interior wall and protect your head with your arms. Do not use the elevators. The alarm or sprinkler system may come on. Stay indoors. DROP, COVER, HOLD

Bed - Hold on and stay there, protecting your head with a pillow

Kitchen - Move away from the refrigerator, stove and overhead cupboards

Stadium or theatre - Stay in your seat and protect your head with your arms. Do not try and leave until the shaking is over. Then leave in a calm, orderly manner


AFTER AN EARTHQUAKE

Be prepared for aftershocks

Do not light a match

Do not move about or kick up dust

Cover your mouth with a handkerchief or clothing

Tap on a pipe or wall so rescuers can locate you

Check for injuries

Check for potential secondary hazards

Remain calm, try to reassure others

Help identify if any staff or family members are missing

Check gas, water, and electric lines

Tune to emergency broadcast system on radio

Move to the assembly area


Ph

oto

: O

tin

Dew

an

/CD

MP

Thank you

For more information contact: Comprehensive Disaster Management Programme (CDMP II) Department of Disaster Management Bhaban (6th Floor) 92-93 Mohakhali C/A, Dhaka-1212, Bangladesh, Tel: (+88 02) 989 0937, 882 1255 Website: www.cdmp.org.bd

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