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 Japan – March 11, 2011 - Fukushima NPP Tsunami se blíží k JE Fukushima JE po průchodu tsunami 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 E- epicentre – projection Of H to Earth's surface
H – hypocentre – point representation of focus
h – focal depth Earthquake parameters Focus = focal domain • geographic co-ordinates of epicentre E Earthquake size is measured by: • focal depth h • Intensity (I), • size
• Energy (ET), • Seismic energy (E) • Magnitude (M) – Richter scale Earthquakes are • Ground acceleration (a), * Shallow – h 50 km • Ground velocity (v), * Intermediate - 50 ‹ h 450 km • ZemětřeseníGround displacement podle h(d), jsou:mělká ( méně* Depth než 50- 4 50km ‹), h ca750 km
• středněSeismic hluboká moment (M (50o) – 400 km), hluboká ( 400 – 750 km ) • Stress drop (σ) 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) S ZP
O P granit Intensity - scales: g C MCS, MSK-64, MM – 12 degree P* JMA – 7 degree bazalt M P n 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.
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 Human lives, health and security EXTREME DISASTER Property
Welfare SECONDARY Environment IMPACTS caused by cascade Energy failures of infrastructures Water DIRECT IMPACTS Sewage
Transport Protection measures Infrastructures Cyber and activities are prepared Finance only for impacts denoted Emergency by bold arrow Products
Governance Nuclear
Technologies Chemical
Bio 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 10 100 log r
0.1
1
It corresponds to focal 10 zone dimension log E / E 0 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. Děčín Liberec PL Teplice Ústí n/L Jablonec Č. Lípa Semily Most Litoměřice Trutnov Chomutov Mělník Louny Ml. Boleslav Jičín Náchod K. Vary Cheb Sokolov PRAHA H. Králové Nymburk Rakovník Kladno Jeseník Pardubice Rychnov n./K. Beroun Šumperk Ústí n./O. Tachov Plzeň Kutná Hora Chrudim Bruntál Opava Ostrava Rokycany Benešov Příbram Karviná Svitavy Domaţlice Frýdek Havl. Brod Olomouc Nový Jičín Klatovy Ţďár n./S. Pelhřimov Prostějov Přerov Jihlava Blansko Vsetín Brno Strakonice Vyškov D J. Hradec Třebíč Zlín
Prachatice Uh. Hradiště Č. Budějovice Hodonín Znojmo Č. Krumlov Břeclav
A SK
WIEN BRATISLAVA
Map of maximum observed intensities (seismic zoning) Earthquake groups Main shock
Foreshocks 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 At management there is necessary to distinguish Disasters – Hazard Risk - Emergency
Related to risk sources Related to protected interests 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.
DISASTERS EMERGENCIES
CAUSES CONSEQUENCES
Prevention, Renovation Preparedness, Response Disaster
Consequences conditions impacts are results of system resilience, vulnerability and adaptability SYSTEM and impacts
NO ACTION SYSTEM AT DISASTER SMALL CHANGE
CHANGES WITH DAMAGES Concept of possibilities of system behaviour at disaster. Needle on balance that decides on consequences, is system (managed subject) vulnerability.
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
Coexistence of systems technological environmental
social 4. To use the third step management and legislation for effective emergency and crisis management Management structure Legislation 5. Safety Cycle. 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. 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
5 4 Unacceptable
3 Conditionally acceptable, i.e. acceptable 2 with measures 1
0 Acceptable P / D 0 1 2 3 4 5
Decision matrix for design disaster management: P – disaster occurrence probability, D - impact size 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.
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
Seismic tests – shaking table 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/