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The Boumerdes (Algeria) Earthquake of May 21, 2003: Preliminary Reconnaissance Using Remotely Sensed Data

By Dr. Beverley Adams, Charles Huyck and Ron Eguchi, Imagecat, Inc.


Map courtesy of USGS and MSNBC

Figure 1. Schematic map showing the location of the earthquake epicenter relative to urban areas such as Boumerdes, which sustained considerable building damage.

As residents of northern Algerian cities settled down in front of their televisions on May 21, 2003 to watch an evening showing of the European Soccer Cup final, their ceilings and walls began to shake and crumble. The magnitude 6.8 earthquake struck at 17:44 local time (USGS, 2003), wreaking extensive damage throughout five Provinces.

Centered in the Boumerdes region (Figure 1, right) some 50km east of the capital city of Algiers, the worst-affected urban areas include the cities of Boumerdes, Zemmouri, Thenia, Belouizdad, Rouiba and Reghaia, together with eastern areas of the capital. According to the latest reports, deaths total 2,266, with a further 10,261 injuries (OCHA, 2003 ). Structural damage within urban areas was severe, with an estimated 150,000 people displaced from their homes (OCHA, 2003), and temporarily re-housed in makeshift tent camps. The May 21st earthquake is the largest to strike Algeria since 1980, when a magnitude 7.3 event caused 3,500 deaths and an estimated $5 billion of damage.

Building Damage Detection

In the immediate aftermath of an earthquake, remote sensing pictures acquired by earth-orbiting satellites offer a bird's-eye view of urban damage. Taking the coastal city of Boumerdes as an example, numerous buildings collapsed or sustained severe damage. From Figure 2, entire apartment blocks were reduced to piles of rubble. Civil structures, such as the police headquarters, were also damaged beyond repair. Today, commercial satellites can easily pick out objects the size of a small car. This makes them an excellent tool for seeking out the hardest hit areas.

Photograph courtesy of AP Photo/Claude Paris

Photograph courtesy of Omar Khemici and EERI Photograph courtesy of Reuters/Larbi

Figure 2. Building damage in the city of Boumerdes, Algeria

Visual inspection of detailed images provides an initial damage assessment for emergency aid organizations, and a focus for response and recovery efforts. Figure 3 shows the extent of 'Quickbird' satellite coverage acquired from DigitalGlobe by the Earthquake Engineering Research Institute (EERI) as part of their Learning from Earthquakes Program. Two images were collected for Boumerdes. The first is dated May 23rd - just 2 days after the earthquake struck. The second, taken just over a year earlier, shows the city as it used to be.

Images courtesy of DigitalGlobe

(a) Before earthquake (4/22/02)

(b) After earthquake (5/23/03)

Figure 3. Multispectral Quickbird satellite coverage of the Algerian city of Boumerdes, acquired (a) before and (b) after the earthquake of May 21st 2003. Visual comparison between these scenes provides a quick look method for identifying collapsed buildings. This technique could play a key role in assessing damage levels and guiding response efforts.

Comparing the pairings in Figure 4 clearly illustrates building damage within Boumerdes. Collapsed buildings are readily distinguished by the chaotic and bright appearance of debris and piles of rubble (Figures 4a-c). Where buildings have pancaked or toppled sideways, changes in shape and position are evident between the 'before' and 'after' scenes (Figure 4d). Figure 4e depicts the tent camps providing residents with temporary accommodation.

Figure 4a - Before

Figure 4a - After

Figure 4b - Before

Figure 4b - After

Figure 4c - Before

Figure 4c - After

Figure 4d - Before

Figure 4d - After

Figure 4e - Before

Figure 4e - After

Images courtesy of DigitalGlobe

Figure 4. (a-d) Building damage in the city of Boumerdes, identified by visual inspection of pan-sharpened Quickbird imagery, acquired before and after the earthquake. (e) An example of temporary tent accommodation for displaced residents. 

MCEER is currently funding research efforts to develop automated methods of building damage detection using high resolution satellite imagery, which will ultimately offer real time damage assessments for emergency responders.


UN Office for the Coordination of Humanitarian Affairs (2003) Algeria - Earthquake OCHA Situation Report No. 9,

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