Damage assessment


Luca Leone
[email protected]
tel: 01223 460475

Broadly speaking, CAR carries out two types of damage survey following a natural disaster: field surveys, typically conducted within 3 to 21 days of the event, depending on conditions on the ground; and remote surveys involving desktop interpretation of aerial photography and satellite imagery. Frequently, both types of survey will be conducted on a single event, allowing CAR to compare the results of the two surveys, and continuously improve the reliability of its remote survey techniques.

Field surveys
Field surveys in the aftermath of a major event are a central aspect of CAR’s work as they have permitted CAR to build up a detailed picture of construction typology and buildings vulnerability in many countries, which is a vital resource in CAR’s vulnerability modelling projects. These field surveys are carried out by a specialist team and involve counting the number of destroyed, damaged and undamaged buildings in sample areas across the affected zone, and classifying damage levels. These data are then collated in Cambridge and correlated with data on hazard intensity levels measured across the same zones.

This information is then used to create new, or refine existing, vulnerability curves for the various building types of the affected country, and thereby to upgrade CAR’s suite of vulnerability models. It can also be used to inform the post-disaster recovery phase, allowing building repair and reconstruction costs to be more accurately estimated.

Earthquake damage surveys
In the case of earthquake, most of CAR’s damage survey work has been carried out through the UK’s Earthquake Engineering Field Investigation Team (EEFIT), organised under the auspices of the Institute of Structural Engineers (ISE) in London. The survey findings are published as reports, which are freely accessible on the ISE website. CAR directors and associates have led or participated in most of EEFIT’s damage surveys since 1989, including the following:

2013: Tohuku, Japan (Recovery Study)
2012: L'Aquila, Italy (Recovery Study)
2011: Tohuku, Japan
2010: Port-au-Prince, Haiti
2009: Western Samoa
2009: L’Aquila, Italy
2008: Wenchuan, China
2007: Pisco, Peru
2005: Indian Ocean Tsunami, Sri Lanka & Indonesia
2001: Bhuj, India
1999: Kocaeli, Turkey
1997: Umbria-Marche, Italy
1995: Kobe, Japan
1994: Northridge, USA
1992: Erzincan, Turkey
1990: Augusta, Italy
1990: Luzon, Philippines
1990: Vrancea, Romania
1989: Newcastle, Australia

Volcanic eruptions
In addition to its earthquake survey work through EEFIT, CAR has carried out its own field surveys of numerous volcanic eruptions, including the following:

2010: Merapi, Indonesia
2010: Eyjafyallajokull, Iceland
1997: Soufriere, Montserrat
1991: Pinatubo, Philippines

With the aid of these surveys, CAR has developed a unique vulnerability database and impact model for each of the volcanic risks affecting building stock: pyroclastic flow, tephra and earthquake.

Remote surveys using aerial and satellite imagery
CAR has developed a suite of methodologies for interpreting aerial photography, pictometry (oblique aerial photography) and satellite imagery for damage assessment following a disaster such as an earthquake, tsunami or hurricane. High resolution imagery of disaster-stricken settlements from Quickbird or Ikonos satellites may be available within 24 hours of the event, allowing rapid damage assessment immediately after the event. The speed of this service makes it suitable for providing a first estimate of the number and geographic distribution of casualties (especially in remote settlements), for identifying blockages to transport arteries, for informing the planning and organisation of disaster relief operations, and for contributing to a post-disaster needs assessment (PDNA).

Vertical and oblique aerial photography normally takes longer to become available but offers better resolution. It is often used to supplement and extend the geographic coverage of ground surveys and to analyse building damage in greater detail. The information gathered from analysing imagery from these sources can be used for the above purposes and also in reconstruction planning.