Earthquake Damage Workshop/Training on Earthquake Vulnerability and - PowerPoint PPT Presentation

Earthquake Damage Workshop/Training on Earthquake Vulnerability and Multi-Hazard Risk Assessment: Geospatial Tools for Rehabilitation and Reconstruction Efforts Siefko Slob INTERNATIONAL INSTITUTE FOR GEO-INFORMATION SCIENCE AND EARTH OBSERVATION

Overview 1. Damaging effects of earthquakes 2. Damage assessment: case study

1. Damaging effects of earthquakes � Direct effects � Ground failures or instabilities due to ground failures � Vibrations transmitted from the ground to the structure � Indirect effects � Consequential phenomena

Direct effects of earthquakes � Ground failures (or instabilities due to ground failures) � Surface faulting or fault rupture/movement � Vibration of soil (or effects of seismic waves) � Ground cracking Causes most damage! � Liquefaction � Ground lurching � Differential settlement � Lateral spreading � Landslide � Vibrations transmitted from the ground to the structure – Site effects

Ground failures � Surface faulting � Ground displacement � Ground cracking � Ground lurching

Surface faulting Normal fault. Scarp near Beni Rached. 1980 El Asnam Earthquake, Algeria

Surface faulting Bent rails of the railroad between Guatemala City and Puerto Barrios caused by the 1976 Guatemala Earthquake

Surface faulting � The 17 August 1999, Izmit Earthquake � Displacements from SAR Interferometry

ENVISAT inSAR � Kashmir Earthquake � 8 Oct. 2005 � Vertical displacement

Vibration of soil: Liquefaction Displacement and tilting of houses due to soil liquefaction in the Turnagain Height area of Anchorage during the 1964 Alaska Earthquake

Vibration of soil: Liquefaction Tilting of apartment buildings at Kawagishi-Cho, Niigata, produced by liquefaction of the soil during the 1964 Niigata Earthquake

Vibration of soil: differential settlement One-story masonry house in a main housing development in the town of Caucete, damaged due to differential settlement caused by liquefaction in the 1977 Caucete Earthquake, Argentina

Direct effects: landslides due to topographic amplification Santa Tecla (Las Colinas) landslide, Jan 13 2001 earthquake, El Salvador

Direct effects: landslides (Kashmir)

Indirect effects of earthquakes, consequential phenomena � Tsunamis � Seiches � Floods � Fires

Indirect effects: Tsunamis � Near-shore or undersea earthquake causing sudden (vertical) movement of the seafloor � As wave approaches shallow water, it slows down, but energy remains constant, causing waves to increase in height (up to 30 m.)

26 December 2004 Sumatra Tsunami

Indirect effects: seiches � Within lake, bay, harbour – enclosed water body � “Bathtub effect”

Indirect effects: flooding caused by regional subsidence � Izmit (Kocaeli) Turkey Earthquake, August 17, 1999

Indirect effect: fires Fire in central Kobe Large fires following strong earthquakes have long been considered to be capable of producing losses comparable to those resulting from the shaking 17 January 1995, Kobe Earthquake

Vibrations transmitted from the ground to the structure � Structural damage: � Torsion � Soft storey � Pounding � Short column � Caused by “site effects”: � Resonance, soft ground effects � Topographic amplification

Torsion � Irregular layout or wrong distribution of weights can create large torsional stresses, resulting in damage and/or failure Plan view

Torsion Lack of torsional resistance in the columns at the periphery of the building Armenia, Colombia 25 January 1999, Quindío earthquake, Colombia M 6.2

Soft storey Soft storey: stiffer structural elements which are present in the upper stories are missing at the ground floor - Gujarat earthquake, 26 Jan 2001

Soft storey The ground floors of many buildings in Turkey are open spaces reserved for stores and show rooms, with insufficient numbers of columns to support the upper floors – Duzce, Izmit earthquake, 17 August 1999, Turkey (M W 7.5)

Pounding � Impact damage � Asymmetry 28 February 2001, Mw 6.8 Nisqually, Washington Earthquake

Pounding Armenia, Colombia 25 January 1999, Quindío earthquake, Colombia M 6.2

Short column

Short column Balcony and inserted brick wall cause short column failure, in combination with bad detailing (lateral reinforcement) - Armenia, Colombia

Detailing Insufficient transverse reinforcement to prevent buckling of the vertical reinforcement Unsufficient lateral reinforcement, bad concrete quality, discontinuity

Masonry � Insufficient cohesion of the masonry walls due to weak mortar or the absence of mortar

Stone masonry: behavior during an earthquake Picture: NSET

2. Damage assessment � Case study: Armenia, Colombia � Rapid Inventory of Earthquake Damage (RIED project) � Assessment of the damage of the 25 January 1999 Earthquake in Armenia and Pereira, Colombia

Objectives � Rapid assessment of the damage inflicted by the 25 Jan 1999 earthquake (M 6.2) � To make recommendations for the reconstruction of the buildings and structures in the damaged areas

Means � High resolution aerial photographs � Integration of existing and new data in an information technology environment to allow fast analyses and visualization for reconstruction

Location map

Earthquake damage inventory by aerial photographs - Methodology � Fly survey as soon as possible after the earthquake before repair and clean-up takes place � Create ortho-rectified digital airphotos for fast on-screen damage assessment � For this a detailed DTM should be available! � Use cadastral maps for base information on building or building blocks footprints and possibly information on building type, age, construction, etc.

Earthquake damage inventory by aerial photographs - Methodology � Structures on aerial photographs were marked in 5 classes: � Total Collapse � Roof Collapse � Roof Partly Damaged � No Damage Visible but Rubble in the Street � No Damage Visible

Total collapse

Roof collapse

INTERNATIONAL INSTITUTE FOR GEO-INFORMATION SCIENCE AND EARTH OBSERVATION

INTERNATIONAL INSTITUTE FOR GEO-INFORMATION SCIENCE AND EARTH OBSERVATION

INTERNATIONAL INSTITUTE FOR GEO-INFORMATION SCIENCE AND EARTH OBSERVATION

INTERNATIONAL INSTITUTE FOR GEO-INFORMATION SCIENCE AND EARTH OBSERVATION

INTERNATIONAL INSTITUTE FOR GEO-INFORMATION SCIENCE AND EARTH OBSERVATION

earthquake damage map for the entire city

Comparison Aerial Survey – Ground Survey � Reasonable correlation for the highly damaged structures such as structures that completely collapsed or for structures of which roof and partially the walls collapsed. � Less correlation for structures with less severe damage.

Results Aerial Photographs Damage Inventory � For reconstruction purposes the inventory gives a good impression of the damage and of major geological, geotechnical, and morphological features that have influenced the damage inflicted on surface structures The presence of such features can then be considered in the planning for reconstruction.

Results Aerial Photographs Damage Inventory (Cont.) The results of an inventory of damage by aerial photographs can be available more rapidly after an earthquake, as compared to a ground survey. This is of great benefit for relief operations and for reconstruction planning.

Exercise – day 5 � Landslide mapping in the Muzzafarabad area using � Aster (15m) VNIR multispectral imagery � Quickbird (1 m) optical imagery

Aster (15 m) VNIR multispectral 18/10/2005 Level 3b Orthorectified by ERSDAC (JAPAN)

Quickbird (1m) From spacemaps by DLR (Germany)

Method: on-screen digitising 1. Create segment boundaries 2. Label segments 3. Correct errors (close polygons) 4. Create polygons 5. Label polygons