Earthquak Disaster Prevention.pdf

A Brochure for Earthquake DisasterPrevention

Prelude

As the Chiayi Rueili earthquake occurred on July 17, 1998, I remember at that

time I was in my office, which is on the 19-th story. Even though the earthquake

intensity was not very large at Taipei, I still could explicitly feel the shaking of the

building and was shocked by the shaking both physically and mentally. Immediately

following the earthquake, damages to house, hotel, school building and bridge were

reported. In addition, 5 people were killed. In the next few days, the rescue was

continued and it is very concerned about whether it is an indication for a severe

earthquake after a lot of aftershocks.

Similar to the typhoon or ocean wave, the earthquake is a part of the natural

activity. However, it is a pity that up to now no one around the world can reliably

predict the occurrence of an earthquake with the right time, right location and right

magnitude as those predicted for a typhoon. Consequently, the earthquake still gives a

great threat for the people resided in Taiwan, such as those resided in Tokyo and

Kobe, Japan, as well as in Los Angeles and San Francisco, U.S.A. since all these

areas are located on the collision boundary of the Eurasian plate.

Although earthquake is unpredictable the damage to life and property can still be

minimized based on the technology developed in Taiwan if the earthquake prevention

is well prepared and the emergency response is appropriately taken. National Science

Council of the Republic of China continues its full support for the research on

seismology and earthquake engineering. In addition, the National Center for Research

on Earthquake Engineering (NCREE) was founded a few years ago. A large structural

laboratory was constructed for the improvement of earthquake resistant design and

the development of new technology for seismic isolation.

The content of this brochure is the research results regarding to the earthquake

itself and its damage prevention from the specialists in the Academia Sinica and in

the ministry of economic and transportation. Hopefully, this brochure can effectively

alleviate the earthquake damage to life and property after reading of it since one can

well prepared for earthquake disaster after recognizing the possible damages caused

by an earthquake.

Knowledge and action are the best prevention when you face an earthquake. Best

wishes!

Catalogue

1. Prelude

2. Organization and Strategy for Earthquake Disaster Prevention and Rescue

l Organization for Catastrophic Disaster Prevention and Rescue

l Community Organization for Disaster Prevention and Rescue

l Guidelines to Reduce Earthquake Damage for Individuals

3. Failure Modes of Buildings under Seismic Loading

Appendix 1. Seismic Hazard in Taiwan Area

1. Introduction

On July 17, 1998, an earthquake occurred at the Chiayi County with a magnitude

of 6.0 on the Richter scale. Since this earthquake is the only earthquake that caused a

severe damage and even the death of people for the recent 30 more years in the area

of Chiayi-Tainan in Taiwan it attracts much attention. In fact, the seismic activity in

this area is widely discussed after a long period of inactivity. Because this event is a

very shallow earthquake the ground shaking near the epicenter is tremendous and

thus the damage to buildings, bridges and roads is inevitable.

Since the tectonic movement continues the seismic activity in Taiwan area will

never be stopped. In fact, an earthquake will occur after the energy is accumulated to

be large enough. Even though the capability to earthquake resistance of a structure is

significantly improved an earthquake with a magnitude over 7.0 might still lead to a

catastrophic disaster and the damage may be more severe than that caused by any of

the pass earthquake events.

This brochure is proposed to provide the general public with the awareness of an

earthquake and the simple guidelines to respond with the earthquake disaster. Hence,

if one has the earthquake preparedness in advance, appropriately responds during the

earthquake and takes the right actions after the event the earthquake damage then can

be effectively minimized.

2. Organization and Strategy for Earthquake DisasterPrevention and Rescue

(a) Organization for Catastrophic Disaster Prevention and Rescue

In order to mitigate the threat from an earthquake, all levels of the government in

the world will generally raises the importance of damage prevention before the quake,

emergency response and rescue during the quake and the recovery after the quake. As

a result, the organization for disaster prevention and rescue is founded. In Taiwan,

these organizations were set up from the central to local governments since 1994. In

addition, the meeting is regularly held by each level of government to propose the

plans for disaster prevention and rescue. These plans can be considered as the

guidelines for the disaster prevention before an earthquake, for the emergency

response and rescue in an earthquake and for the recovery after an earthquake.

As a catastrophic disaster occurs, the procedure to damage prevention and rescue

will be preceded by the government as follows:

(a-1) The government infrastructure for

disaster prevention and rescue, such

as the fire fighting department and

the police department, should

collect the information about the

emergency faced and go to the

rescue immediately.

(a-2) Report the damage to the authorized government agencies. Then, they will

organize a team to respond with rescue and

recovery operations according to the plan for

emergency response.

(a-3) The authorized government agency should

report to the responsibilities of the district

administrator to establish the “Emergency Response

Center” for the emergency management and rescue.

(a-4) If the government infrastructure cannot handle the disaster rescue or

recovery it should make a request for assistance from the higher level of

government. The level of government to assist the emergency response and

rescue is dependent upon the actual need of

emergency faced.

(b) Community Organization for Disaster Prevention and Rescue

Disaster prevention and rescue involves every one, family and community. In

addition, community organizations for disaster prevention and rescue are the basis of

the national organization for disaster prevention and rescue. They can reduce the

causes to disasters in the usual time and in a disaster they will go to rescue first. In

fact, in case of disaster the elected district administrators, such as town supervisors or

village executives, should assemble their members to involve the immediate rescue.

This may include emergency medical services, fire fighting, shelter, food, water and

essential services. A well-coordinated emergency response to an earthquake is likely

to save many lives and prevent earthquake-induced hazards escalating the magnitude

of the disaster.

(b-1) Development of the Community Organizations:

It is necessary to set up a community organization for disaster prevention and

rescue based on the conditions and needs of the specific district region. The

following skeleton is used to

illustrate a possible

community organization.

(b-2) Emergency Preparedness:

Community organizations can promote participation in emergency

preparedness activities and help organize practice drills and exercises to raise

awareness and ensure that everyone knows what to do. In addition, a

community disaster plan can also be drawn up, involving fire-fighting, search

and rescue, first aid, making contact with

authorities, supervision of food, water and

power provisions.

(b-3) Emergency Response:

Pre-earthquake emergency planning is one of the best ways to ensure that the

earthquake disaster can be handled effectively. In fact, as a disaster occurs,

using this plan with the usual

practice drills and exercises for

emergency response and rescue.

Supervisor

shelter guide fire fighting

food supply Casualty Savage information report

(b-4) Recovering from Earthquakes

Fit in with the government to gather data on the extent of damage and its

distribution in the community. In addition, help each other to recover from

the disaster.

If the earthquake causes people injured or a great loss, make a request for

assistance from the local government or call 119 for help.

3. Guidelines to Reduce Earthquake Damage forIndividuals

(a) Before the Earthquake

(a-1) At Home

(a-1-1) Reinforcing shelving, fixing tall

furniture to the wall and keeping

items low and safe will make your

living environment a safer place.

(a-1-2) Recognizing the shelters and their

routes both at home and nearby.

(a-1-3) Recognizing the place of switch for

gas and electricity and how to turn off.

(a-1-4) Preparing an emergency box

and fire extinguishers. Let all

the family members know

where they located and how to

use them.

(a-1-5) In case of any problem in the

building, ask licensed engineers

or agencies to check and retrofit

it.

(a-1-6) Check the equipments for

fire fighting and exercise the plan

for disaster prevention and rescue

regularly if you are living in a

high-rise building.

(a-2) In the Public Place

(a-2-1) Propose an emergency plan and

assign the staffs or servers to take in charge

of the disaster prevention and emergency

response.

(a-2-2) Check the equipments for

fire fighting regularly.

(a-2-3) Exercise the disaster

prevention regularly.

(a-2-4) Check the billboard and the

shelter from the sun or any other

potentially dislodged item

constantly.

(b) During the Earthquake

(b-1) indoors

(b-1-1) Turn off gas, electricity and

water supplies.

(b-1-2) Using an appropriate exit to

keep away from any

congestion in a public place.

(b-1-3) Open the door in order to avoid

that the door is jammed by the large

deformation in an earthquake.

(b-1-4) Stay away from the glass window

and find a safe shelter.

(b-1-5) Sit

or lie down beside or underneath a

table or bed to protect against

possible objects falling from

above.

(b-1-6) Keep calm and do not rush out in

panic.

(b-1-7) In case of fire put it out right away.

(b-1-8) Do not use the elevators but use

the stairs.

(b-2) outdoors

(b-2-1) If you are driving a car or

riding a bike do not stop

immediately. In stead, drive the

car or ride the bike to the

roadside and then find a shelter.

(b-2-2) If you are walking

in the street, run

into an open space

or the pedestrian

corridor.

(b-2-3) Keep away from the gas

station, glass curtain wall, vending

machine, electric pole and

construction site, etc.

(b-2-4) Look out for any possible

objects falling from

above and put your arms

on your head.

(b-2-5) If you are on a bus or a train,

do not panic and jump outside.

Stay in the bus or train

temporarily and put your arms or

a bag on your head.

(b-2-6) If you are in a suburb, stay

away from the hill, riverside

and seaside and find an open

space for shelter.

(b-2-7) If you are on a

viaduct or an

underground passage,

walk away calmly and

immediately.

(c) After the Earthquake

(c-1) Help each other for the disaster

rescue. Have a look at the other buildings

nearby. Their occupants may need your

help.

(c-2) If electric power is recovered after the

power shutdown, do not use any electric

devices right away but check first whether

there is a leak of gas to keep away from any

explosion or fire.

(c-3) Listening to the radio or watching TV

any time and escaping from any rumor.

(c-4) Do not use the

telephone unless somebody

has been injured or a

building is damaged or

burning. The emergency

services may need all lines

for the rescue.

(c-5) Inspect the house for cracks. If

beams or columns are damaged leave

the house as soon as possible and ask a

civil agency to inspect and restore.

(c-6) If the gas pipeline is damaged or

there is a smell of gas, do not use any

gas or electric devices. Open the doors

and leave the house immediately. In

addition, report to the authority.

3. Failure Modes of Buildings under Seismic Loading

The habitation is always closely related to the human beings. Ancient people

resided in caves to shelter from the wind and rain. Following the progress in the

civilization of human beings, the construction materials for buildings are gradually

improved in the order of timber, rock, brick, reinforced concrete and steel. All the

buildings are located on the ground or even fixed into the ground. Therefore, when a

building is excited under an earthquake, its base tends to move with the ground where

it is supported. Taiwan area is in the time of high potential of the occurrences of

earthquakes. Furthermore, it can be expected that a lot of structures will be destroyed

to a different degree of damage if a strong earthquake occurs at the present time.

Some will be totally collapsed and some may be damaged and need to be retrofitted.

However, each structure must be well reevaluated by the engineers. The following

figures or photos are used to illustrate the general failure modes of buildings under

seismic loading.

Brittle Failure at the End of a Column

Since a reinforced concrete column will in

general be subjected to a maximum moment at

its ends adequate stirrup reinforcement is

needed at the column ends. If the stirrup

reinforcement is too short or widely spaced

brittle failure may occur at the column end due

to the inadequate confinement in longitudinal

bar and concrete. If this occurs in several

columns of the same story this building may be

collapsed at any story.

Failure of the Short-Column Type

In general, the design of a column is based

on its net height. However, the window above half-height in-filled shortens the

effective length of the column. This may cause the shear force to be greater than the

shear capacity possessed by the column and finally might result in a diagonal shear

crack in the column. This is the so-called “short-column” type damage.

Punching Shear Failure

When two-way slabs are supported

directly by columns, such as in flat slabs and

flat plates, or when they carry concentrated

loads, such as in footings, punching shear near

the columns is of critical importance. For the

failure of punching shear, the potential

diagonal crack follows the surface of a

truncated cone or pyramid around the column.

Unfixed Heavy Objects in the Top Story

During an earthquake, the top story

response is generally greater than the low story

response and then it will experience a larger

seismic force. As a result, if any heavy object in

the top story is not fixed tightly it may fails or

falls down in an earthquake.

Interaction of Axial Load and Side-Sway

An axially loaded column accompanying with a

side-sway will cause the secondary moment for the

column. Thus, the increase of the axial loading may

result in the buckling or yielding of the column and

eventually the collapse of a whole story.

Pounding Failure

Individual building need to be provided with

adequate separation, to prevent damage caused by

pounding when deform in earthquake, which has been a

serious cause of damage to multistory structures, even of

collapse, in recent earthquakes. The minimum separation

gap depends on the height of building and on the

flexibility of the building. The gap between buildings

should exceed the maximum drift of each story with an

extra allowance.

Failure of Accessory and Nonstructural Element

Accessory of a building such as the water

tank, TV and elevator and the nonstructural

element such as the curtain wall, interior

partition and staircase may be destroyed by the

large deformation due to a severe earthquake.

Especially, the break of elevator and collapse of

the interior partition may damage to life.

Failure of the Pre-damaged Structural Element

The capability to earthquake resistance of a

structural element may be reduced due to the

implementation of a nonstructural element. For instance,

a drainpipe is usually embedded in the column. Thus,

the effective area for the column to resist the axial force

is reduced. Furthermore, if there is a leak in the

drainpipe the concrete and steel will be corroded with

the time passing. Consequently, this structural element

will be damaged prior to the other structural elements

and may lead to collapse of the whole building.

Slope Failure

Sloping ground or rock masses, which are

stable under normal loading, can lose their

stability during an earthquake causing effects

from a slow progressive creeping of the

ground to dramatic landslide or rock fall.

Whether sudden or slow, such slope failures

are liable to cause complete destruction of any

building founded on them or in the path of the

slide. Landslide and later spreads can also

cause extensive property damage.

Fault Rupture Failure

Large permanent ground deformations often

occur at the surface associated with fault

ruptures in earthquake. Vertical and horizontal

displacements have occurred across fault breaks;

where this relative movement occurs under a

building, a bridge or any structure catastrophic

damage can result.

Foundation Failure due to Soil Liquefaction

Earthquake-induced soil liquefaction has been the cause of catastrophic damage

in a number of earthquakes. Certain types of soils, when they are saturated with water

and then suddenly shacked by an

earthquake, completely lose all shear

strength, and flow like a liquid. The

support to the foundations of buildings or

bridges built on such soils then disappears,

and they can plunge into the ground, or be

carried sideway bodily on unliquefied

masses of soil.

Appendix: Seismic Hazard in Taiwan Area

1. Causes of Earthquakes

l Distribution of Earthquakes

The distribution of earthquakes in the world is well recognized after the study of

several decades. It is concluded that earthquake occurrences are not distributed

uniformly over the surface of the earth; instead they tend to be concentrated

along well-defined lines, which are known to be associated with the boundaries

of plates of the earth’s crust. There are three principal world zones or belts of

earthquake activity. They are the Circum-Pacific seismic zone, the Eurasian

seismic zone and the Mid-oceanic ridge. It is worth noting that some large and

highly destructive earthquakes do occur in continental zones but not in the three

principal world zones mentioned above. In fact, there are the so-called intra-plate

earthquakes, such as the 1812 New Madrid earthquake in Missouri, U.S.A. and

the 1976 Tangshan earthquake in China.

The island of Taiwan is located at the Circum-

Pacific seismic zone and thus seismicity is

extremely active in this country. Based on the

distribution of the recorded earthquakes,

Taiwan can be roughly divided into three

seismic zones. They are the northeastern

seismic zone, the eastern seismic zone and the

western seismic zone as shown in the figure.

Most earthquakes occurred in the eastern and

western seismic zones are shallow earthquakes

while shallow-, medium- and deep-focus

earthquakes are common in the northeastern

seismic zone.

WesternEarthquakeBelt

Legend

Earthquake with Surface Rupture in Taiwan

Earthquake withSurface fracture

NorthernEarthquake Belt

EasternEarthquakeBelt

l Active Fault

An earthquake may be induced by many causes, such as volcanic eruptions, the

collapse of underground mine-workings, man-made explosions and the fault

ruptures. However, the fault rupture causes the most earthquakes and thus is of

importance. In fact, about 90% earthquakes are tectonic earthquakes in the world.

An active fault implies its recurrent movement for a specific period of time.

However, a given time period may not be satisfied for all the users of different

purposes under different tectonic settings. Recently, Central Geological Survey

has collected all the active fault data in Taiwan area and gives the definition for

an active fault. In fact, it will be considered as an active fault if there is recurrent

movement in the late Quaternary period. Furthermore, active faults are classified

into two categories based on the identified period of last movement. The first

category of active faults includes those (1) activated in the Holocene, (2) offset

(creep) the man-made structures, (3) relate to recent large earthquakes, (4) offset

the recent alluvium and (5) show the creeping phenomena as verified by the

present geodetic method. On the other hand, the second category of active faults

is those (1) activated within the last 100,000 years or (2) offset the terrace

deposits or tableland deposits. In addition, some

active faults are not classified into the two

categories due to the lack of geologic evidences

and are considered as suspect active faults. The

distribution of active faults, whose fault trace is

greater than 5 km in Taiwan area, is shown in

figure with a scale of 1:500,000 geological map.

There are 51 active faults in total, 9 are in the

first category, 15 are in the second category and

the rest 27 faults are the suspect active faults. Active FaultsIn Taiwan

2. Possible Earthquake Damages

The movement of tectonic plates

may lead to the fault rupture and then

results in an earthquake. When the

rupture occurs, the release of strain

adjacent to the crack surface will be

accompanied by a sudden relative

displacement of the two sides. Thus, a

displacement wave is initiated by this

rupture and will be propagated radially

from the source. Consequently, the

severe ground shaking introduced by

the earthquake wave may cause

damage to the structure, life and

property. In general, earthquake

damages can be simply classified into

two types, which are the direct and

indirect damages.

A fault rupture may lead to tsunamis, landslide, large ground deformation, soil

liquefaction and then the damage to structures. All these can be considered as the

direct damage. On the other hand, the indirect damage implies secondary disasters

triggered by the earthquake or the earthquake-induced accidents. Flooding following

earthquakes may result from the failures of reservoirs or embankments. The failure of

pipeline may lead to a leak of gas or a fire arising from the short circuit. In addition,

the overturning of building contents and equipment may also impair life. It should be

mentioned that more fatalities are caused by the failure of nonstructural elements or

by earthquake-induced accidents than are caused by the collapse of buildings.

Landslide Surface Rupture

Landslide

Tsunamis

Bridge Broken

Building Collapsed

fire

When the earthquake occurs, it might cause… .

Leak of poison gas in factory Catastrophic damage

The difficulty to resoue

The difficulty for fire fighting

The Epicenter Map of the most severe Earthquakesin Taiwan,1898-1998

3. Earthquake Disasters in Taiwan

The history of seismic activity in Taiwan can be dated back to the seventeenth

century. Prior to 1897, the historical records of earthquakes are made up of local

governmental documents and personal diaries and accounts. In 1897, seismographs

were first installed in Taiwan. After the use of seismographic instruments, there were

125 destructive earthquakes between 1898 and 1998. The greatest earthquake is the

one occurred on June 5, 1920 at Hualien. The magnitude of this earthquake is as large

as 8.0. According to the past earthquake data, the most active seismic zone in Taiwan

is near Hualien and Ilan region. Meanwhile, most destructive earthquakes occurred in

the western region of Taiwan are in the area of Hsinchu, Taichung, Chiayi and Tainan.

Among the 125 destructive earthquakes, 30 events occurred in the western region.

Even though the occurrence rate in the western region is lower than that of the eastern

region, the earthquake disasters caused in this region are more severe than those of

the eastern region. Hence, this needed to be greatly considered in construction.

Observing the earthquake events

recorded by the seismographic

instruments from 1898 to 1998, the

magnitude, epicenter, tectonics and

building type of the most severe 10

events are different. Thus, each caused a

different degree of damage. In general, if

the epicenter is in mountainous terrain

such as the 1998 Ruilei earthquake,

landslide is the major geologic damage.

However, in plains the major geologic

damages are the fault rupture, surface

break, quick sand, and soil liquefaction.

What kind of geologic environment is apt

to have above geologic damages? In

plains, the geologic damages such as the offset, surface break and quick sand mainly

caused by the fault rupture. Liquefaction is most likely to occur in loose cohesionless

soils, such as fine sand or silts; these are most commonly found in sea or river

deposited sediments. These geologic damages may lead to the collapse of structures

and the destruction of pipelines. Landslides may occur at the steep slopes in

mountainous terrain. Thus, it is very important to protect the building and road from

rockfalls and mudflows by using a retaining structure.