principles of the seismology and seismic engineering · seismology – science dealing with...

Principles of the Seismology and Seismic

Engineering

Assoc. Prof. RNDr. Dana Prochazkova, PhD., DrSc.

Czech Technical University in Praha

CONTENT

Introduction

Earthquake causes

Earthquake characteristics

Earthquake impacts and their consequences

Seismic regime

Seismological characteristic of Europe

Seismic vulnerability, mitigation, prevention and response

Principles of seismic protection in national standards, EU civil

protection directives and the IAEA standards

Earthquake

- is a physical phenomena that is a consequence of

processes that lead to accumulation of energy in

limited space in the Earth interior and to its sudden

release if energy size exceeds physical material limits

(stress limit, phase transition limit),

- is observed as vibrations of the Earth's surface of a

different intensity,

- causes harms and losses on human assets, i.e.

human lives and health, property, infrastructures and

environment. Greek philosopher Aristotle classified earthquake

into 6 categories according to observed Earth ´s surface

movements. Chinese scientist Chan Chen constructed instrument

for earthquake registration in 132 AD.

Seismology – science dealing with earthquakes

Seismic engineering – the discipline the aim of which

is to construct infrastructures and buildings resistant to

earthquake and similar phenomena impacts and by this

way to protect human lives and health and human

property.

Seismicity – general term.

Instrumental seismology – half of 19th century.

1897 – mathematical theory of the P (longitudinal –

primary), S (transversal – secondary) a L (surface) waves

Physical models of earthquake – rheology.

Earthquakes – enable the Earth's interior research

(Earth's crust, mantle, external core, internal core and its

parts).

Bucharest - March 4, 1977

Spitak - December 7, 1988

Dolní Žandov - December 21, 1985

Petrochemie in Izmit – August 17, 1999

Petrochemie in Izmit – August 17, 1999

Petrochemie in Izmit – August 17, 1999

Japan – March 11, 2011

Japan – March 11, 2011

Zaplavené letiště v Sendai

Japan – March 11, 2011 – Sendai airport

Tsunami se blíží k JE Fukushima JE po průchodu tsunamiJapan – March 11, 2011 - Fukushima NPP

After earthquake After tsunami

Recorded seismic events:

• natural earthquakes,

• induced earthquakes – man-made, induced by human activities

• artificial explosions,

• vibrations of natural or artificial origin – consequences of technological processes and natural phenomena as fall of meteorites, aircrafts, bombs etc.

Tsunami - waves on sea induced by earthquake the focus

of which is under the sea bottom.

Mikroseisms – permanent Earth's surface vibration.

Faults – foci of natural earthquakes in Earth's Crust and Upper Mantle

Strike slip

Thrust

Normal

Natural earthquakes are of:

• tectonic origin (90%),

• volcanic origin (7%),

• collapse of underground spaces (3%)

The most harms and losses on human assets are caused by

tectonic earthquakes.

Earthquake epicentres in last 800 years

Microearthquakes 1980 - 2000

Induced (man-made) earthquakes – artificially triggered

seismicity

• cause - the perturbation of the underground mechanical equilibrium, due

to industrial activities (mining, dams, geothermal, hydrocarbon reservoirs),

induce deformation of involved sites,

• located in different tectonic settings,

• types:

* reservoir - induced seismicity - e.g. Lake Kremasta in Greece 1966,

* rockbursts – mining – rockfalls, shaking, bumps, outbursts (methane

release),

* seismicity triggered by injection of fluids into rocks - special

technology of mining,

* seismicity triggered by withdrawn of fluids from surface formations –

special technology of mining,

* earthquakes stimulated by seismic vibration signals - special

technology of mining,

* stimulated by artificial explosions (mining regions, test sites).

Earthquake foci

– mostly on lithosphere plates boundaries

Daily is recorded ca 8000 earthquakes with magnitude 2 or

lower

Annually is recorded:

• ca 7000 – 9000 medium earthquakes with magnitude 4 and

higher,

• ca 18 – 20 strong earthquakes with magnitude 6 – 7,

• at least 1 very strong earthquake with magnitude 8 and

higher

Earthquake Mw Mo (dyne-cm)

1960 Chile 9.6 2.5 x 1030

1964 Alaska 9.2 7.5 x 1029

1906 San Francisco 7.9 9.3 x 1927

1971 San Fernando 6.6 1.0 x 1026

1976 Tangshan 7.5 1.8 x 1027

1989 Loma Prieta 6.9 2.7 x 1026

1992 Cape Medocino 7.0 4.2 x 1026

1994 Northridge 6.7 1.3 x 1026

1995 Kobe 6.9 2.5 x 1026

2004 Indonesia 8.4 1.3 x 1028

2010 Haiti 8.0 2.5 x 1027

2011 Japan 9.0 2.5 x 1029

Zemětřesení podle h jsou:mělká (méně než 50 km),

středně hluboká (50 – 400 km), hluboká ( 400 – 750 km )

E- epicentre – projection

Of H to Earth's surface

H – hypocentre – point

representation of focus

h – focal depth

Focus = focal domain Earthquake parameters • geographic co-ordinates of

epicentre E

• focal depth h

• size Earthquake size is measured by:

• Intensity (I),

• Energy (ET),

• Seismic energy (E)

• Magnitude (M) – Richter scale

• Ground acceleration (a),

• Ground velocity (v),

• Ground displacement (d),

• Seismic moment (Mo)

• Stress drop (σ)

Earthquakes are

* Shallow – h 50 km

* Intermediate - 50 ‹ h 450 km

* Depth - 450 ‹ h ca750 km

Total energy release at earthquake at time interval dt - dW

dW = mechanical energy (performed work – deformation + kinetic energy) +

heat energy

Seísmic energy – part of kinetic energy

E = ∫ ∫ ε dS dt,

0 S

- c

En = Eo exp (- d Dn) Dn .

Dependence of seismic energy on magnitude: log E = 11.3 + 1.8 M

I

A- seismic wave attenuation: log a = ---- - 0.5

3

Intensity attenuation

Kövestligethy formula: Io - In = 3 log (Dn / h) + 3 log e (Dn – h) α

Blake formula: Io - In = k log (Dn / h)

Bohemian Massif: log E = 12.40 + 1.13 Io

Gutenberg-Richter: log E = 11.3 + 1.8 M

Seismograph – instrument for recording the earthquakes (if ground

acceleration is measured – accelerograph)

Seismogram – earthquake record (in case of ground

acceleration recording – the accelerogram)

Magnitude – C. F. Richter 1935

M = log (A/T)max + (, h)

A – amplitude, T – period, - correction function (depends on wave type), - epicentral distance, h – focal depth)

Intensity - scales:

MCS, MSK-64, MM – 12 degree

JMA – 7 degree

Travel time curve - f (, h) - dependence of time spreading the

real wave on epicentral (hypocentral) distance – it depends on

wave type - t ( r ) = T - H ; time in site, time in focus.

O

SZP

C

M

granit

bazalt

Pg

P*

Pn

Isoseismal map - scenario of earthquake impacts

Typical isoseismals – isoseismal form depends on focal

region and on focal depth.

Empirical relations derived for Europe, M = 4.5 – 7.4, shallow

earthquakes:

log Mo = (9.95 0.24)+(1.40 0.14) M

log = - (3.15 0.24)-(0.29 0.09) R + (1.01 0.08) M

log = - (20.96 0.53)-(0.13 0.05) R + (1.26 0.18)log Mo

log u = - (2.60 0.11)-(0.39 0.09) R + (0.63 0.02) M

R- focal dimension, u – fault displacement

[Mo] = N m, [R] = km, [ ] = MPa, [u] = mm

Vrancea intermediate earthquakes:

log Mo = (8.98 0.80) + (1.5 0.12) M

PHYSICS: Mo

= μ AZ u

μ – torsion modulus, AZ

– active fault plane, u – fault displacement

EARTHQUAKE IS completely DESCRIBED BY 2

PARAMETERS – e.g. M and or Mo and !!!!!!

Relation among the focal parameters

Mw – Kawasaki / moment magnitude – derived from seismic moment (greater than

M calculated from seismic waves)

Seismogram: P vlny – 6 km/s; S vlny – 3.3 km/s; L vlny – 3 km/s

Length of time interval between P and S inputs depends on

epicentral distance and recording place.

With increase of epicentral distance the seismogram

complexity increase as a consequence of recording the

reflected, surface and other wave types.

There are earthquakes the records

of which do not respect present

standards on earthquake record

Spectrum of acceleration in near zone – different from distant

zone (red zone – strong dependence on local geological structure)

Differences in focal

mechanisms (documented

by amplitude rate S to P

changes) of near

earthquakes

Fault structure in

Western Bohemia –

causes of different

earthquake

mechanisms

Reaction of buildings to seismic waves

EXTREME

DISASTER

Human lives, health and security

Property

Welfare

Environment

Infrastructures

Technologies

Energy

Water

Sewage

Transport

Cyber

Finance

Emergency

Products

Governance

Nuclear

Chemical

Bio

DIRECT IMPACTS

Protection

measures

and activities

are prepared

only for

impacts denoted

by bold arrow

SECONDARY

IMPACTS

caused by

cascade

failures of

infrastructures

Accelerograms

Response spectra – RG 1.60 (US NRC)

Response spectra

Response spectrum - Atomenergoproject

Real response spectra

Intensity attenuation with distance – usually azimuthal

variations are observed in each focal region

log

E0 / E

0.1

1

10

100 log r 10

It corresponds to focal

zone dimension

Energy attenuation with distance

Acceleration attenuation with distance – strong regional

The earthquake foci mostly concentrate to regions

that we called “focal provinces – zones, regions”.

The boundary of focal provinces are defined as a

boundary that surrounds:

• all known earthquake foci occurring in the historical time

and in the case when there are the reliable evidence on pre-

historical foci from the research of paleoseismicity, so the

boundary also includes those,

• the region in which the earthquakes with the same

characteristics of seismic regime occur,

• the region with the same geological, tectonic and recent

movements characteristics.

Map of focal regions and regions with diffuse seismicity

Findings from research of earthquakes :

1. From earthquake foci space distribution it follows that earthquake foci

are mostly connected with faults.

2. In recent period only certain parts of faults are seismoactive, namely

in both, the vertical and the horizontal plane.

3. Earthquakes often originate on fault crossing. Mostly one of the fault

is preferred in historical time form earthquake occurrence viewpoint.

4. In some cases after strong earthquake connected with one fault

system it follows earthquake connected with other fault system – they

have different characteristics.

5. Isoseismal form in epicentral zone depends on fault-plane

mechanisms, in distance zone on material properties –

boundary r 2.5 h.

6. Isoseismal surface sizes depends directly on earthquake size and

focal depth and indirectly on intensity attenuation.

Seismic regime of focal zones:

• is variable in time and space,

• has a certain prevailing character in each focal zone,

• is described by:

* Benioff´s graphs,

* occurrence frequency,

* earthquake group types,

* space-time foci distribution,

* strong earthquake foci migration sometimes,

• in short term viewpoint is determined by value of stress

drop:

high - low value of the highest aftershock and low number

of aftershocks,

low - high value of the highest aftershock and great

number of aftershocks.

Benioff´s graphs

E – energy

t – time

Frequency graph – distribution of earthquake number

according to earthquake size – usually it is used the cumulative

frequency in which the sum starts at the biggest earthquake

Maximum Possible Earthquake in focal zone

• predetermined by physical focal zone condition,

• ways of determination:

* sum of size of maximum observed earthquake in the

historical time and 1 MSK-64,

* extrapolation of oscillations of the Benioff`s graph,

* curvature of magnitude – frequency graph in the

range of strong earthquakes,

* correlation of maximum observed earthquake with a

seismic activity defined for the selected level of

earthquake activity,

* theory of extreme values,

* correlation of maximum earthquake size with a fault

length,

* geodynamic factors.

Cheb

Tachov

Sokolov

Domaţlice

Strakonice

Klatovy

Rokycany

Příbram

Č. Krumlov

Prachatice

J. Hradec

Benešov

Beroun

KladnoRakovník

K. VaryLouny

Chomutov

Most Litoměřice

Teplice

Děčín

Č. Lípa

Liberec

MělníkMl. Boleslav

Nymburk

Kutná Hora Chrudim

Pardubice

Jičín

Semily

Trutnov

Jablonec

Náchod

Rychnov n./K.

Ústí n./O.

Havl. Brod

PelhřimovJihlava

Ţďár n./S.

Svitavy

Třebíč

Znojmo

Vyškov

Blansko

Prostějov

Olomouc

Přerov

Šumperk

Bruntál

Opava

Nový Jičín

Frýdek

Karviná

Vsetín

Zlín

Uh. Hradiště

Hodonín

Břeclav

PL

D

A SK

Plzeň

Ústí n/L

H. KrálovéPRAHA

Č. Budějovice

Brno

Ostrava

WIEN

BRATISLAVA

Jeseník

Map of maximum observed intensities (seismic zoning)

Earthquake groups

Foreshocks

Main shock

Aftershocks

Main shock

Aftershocks

Earthquake swarm

Earthquake swarm in Western Bohemia

Aftershock area – 200 x 500 km

Items that must be followed for seismic protection

Disasters – Hazard Risk - Emergency

Contexts:1. Human system is open dynamic system in which there are processes, actions,

phenomena and events the sources of which there are inside and outside of system.

The disasters are their results.

2. The disaster occurrence in a certain site and time causes in dependence on disaster

size and physical nature, and on amount and vulnerability of protected interests in a

given site the looses, damages and harms on protected interests, i.e. emergency.

At management there is necessary to distinguish

Related to protected interestsRelated to risk sources

Prevention, Renovation Preparedness, Response

DISASTERS EMERGENCIES

CAUSES CONSEQUENCES

impactsconditions

SYSTEM

SYSTEM

AT DISASTER

NO ACTION

CHANGES

WITH

DAMAGES

Disaster

SMALL CHANGE

Concept of possibilities of system behaviour at disaster.

Needle on balance that decides on consequences,

is system (managed subject) vulnerability.

Consequences

are results of

system

resilience,

vulnerability

and adaptability

and impacts

Protection principles

1. To distinguish causes (phenomena) and

consequences (events, emergency situations)

Earthquake = Disaster

From safety viewpoint: Causes are characterized by quantity hazard.

Consequences are characterized by quantity risk.

2. For human protection we must protect

public assets and to consider all disasters,

i.e. so called „ALL HAZARD APPROACH“

3. To consider that reality is system of systems

(i.e. set of systems that are mutually

interconnected) - to consider vulnerability,

resilience and adaptation capacity and the reality that we need to ensure

technological environmental

social

Coexistence

of systems

4. To use the third step management and

legislation for effective emergency and crisis

management

Legislation Management structure

Prevention - introduction of

protection measures against

disasters occurrences and

disasters impacts

enhancements, active and

passive.

Preparedness (and

readiness) - introduction of

measures enhancing our

capability to put disasters

under the control.

Response - implementation

of measures putting the

disaster impacts under the

control, with adequate losses

and adequate sources.

Renovation -

implementation of measures

for assurance of area

reconstruction return to a

stabilized conditions and start

of further human society

development.

5. Safety Cycle.

6. The effectiveness of measures and activities

is different.

The most effective measures and activities by that we

can avert the disaster occurrences and mitigate their

impacts are preventive measures (procurators), the

effectiveness of which is the following:

1. Technical measures use in the area of land-use

planning - about 60 - 80%.

2. Population education and training - about 20 - 30%.

3. Emergency and crisis management (strategic

planning)-about 25 - 40%.

4. Installation of warning and alarm systems - about 9

- 40%.

7. Human, technical and financial sources,

forces and means are limited good

governance is necessary – tool decision

matrix

543210P / D

0

1

2

3

4

5

Unacceptable

Conditionally

acceptable, i.e. acceptable

with measures

Decision matrix for design disaster management: P – disaster occurrence

probability, D - impact size

Acceptable

8. To use all state tools for safety support:

1. Strategic safety management with aim security

and

sustainable development.

2. Training and education of population.

3. Specific training the technical and senior managers.

4. Technical standards, norms and regulations, i.e. the

regulation of processes that can or could result to an

occurrence (origination) of disaster.

5. Research – theoretical and experimental

6. Inspections.

7. Efficient forces for putting the disasters under the

control (e.g. fire-fighters, police, medical doctors).

8. Emergency and crisis managements belonging to

standard state strategic management.

Seismic tests – shaking table

9. Reserves for crisis management

1. Emergency management uses standard forces,

sources and means.

2. Crisis management uses standard + beyond

standard forces, sources and means

RESEARCH IS IMPORTANT

State safety management system ensuring the

disaster protection in the EU and its Member States:

1. Guarantees the protection of human lives and health,

property, environment and technical infrastructure.

2. Considers all relevant disasters with possible occurrence

on its territory and against relevant disasters it carries out

the prevention and preparedness with regard to their

impacts.

3. Forms the professional base, managerial structure,

efficient forces, means, substances and sources to ensure

protection of human lives and health, property,

environment and of the state.

4. Forms the professional base, managerial structure,

efficient forces, means, substances and sources to ensure

renovation after disaster and after crisis.

IAEA Safety Guides for seismic domain

1. IAEA 50-SG-S1 - Earthquakes and Associated Topics in Relation to

Nuclear Power Plant Siting: A Safety Guide. Vienna 1978.

2. IAEA 50-SG-S1 (REV 1) - Earthquakes and Associated Topics in

Relation to Nuclear Power Plant Siting: A Safety Guide. Vienna 1991,

59p.

3. IAEA No. NS-G-3.3. Evaluation of Seismic Hazards for Nuclear Power

Plants. Safety Guide. No. NS-G-3.3. ISBN 92-0-117302-4, IAEA,

Vienna 2002, 31p. www.iaea.org/ns/

4. IAEA No. SSG-9 - Seismic Hazards in Site Evaluation for Nuclear

Installations. Specific Safety Guide No. SSG-9. ISBN 978–92–0–

102910–2, IAEA, Vienna 2010, 62p. www.iaea.org/books

5. IAEA No. NS-G-1.6 - Seismic Design and Qualification for Nuclear

Power Plants. ISBN 92-0-110703-X, IAEA, Vienna 2003, 58p. www-

ns.iaea.org/standards/