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Figure from:Seismic risk and loss assessment for Bucharest, Romania

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Figure 7.

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Figure 1. Overview map of the city of Bucharest with its six main city sectors (areas filled with bright color) which are extended to the administrative city limits (areas filled with toned color). Figure 2. The city of Bucharest and its distance to the earthquake-active Vrancea zone. Note the different colors reflecting on focal depth ranges of the PDE (what is PDE?) located earthquakes between 1973 and 2009. Figure 2. The city of Bucharest and its distance to the earthquake-active Vrancea zone. Note the
Figure 1. Overview map of the city of Bucharest with its six main city sectors (areas filled with bright color) which are extended to the administrative city limits (areas filled with toned color). Figure 2. The city of Bucharest and its distance to the earthquake-active Vrancea zone. Note the different colors reflecting on focal depth ranges of the PDE (what is PDE?) located earthquakes between 1973 and 2009. Figure 2. The city of Bucharest and its distance to the earthquake-active Vrancea zone. Note the
Table 1. Distribution of the population and building inventory (residential only) in each of the si sectors of Bucharest. The available building database contained several parameters that could be used for th« subdivision into building classes: main construction material; building class; period o construction; height class; number of dwellings (ec. number of apartments or living units and number of occupants. The information given in the database was combined with thi experience of local engineers and provided basis for a building typology classificatior according to the main structural material so that seven “Bucharest’-specific buildin; typologies were initially defined (Table 2). These seven main residential typologies wer further subdivided into 31 model building types for which damage computations ar conducted and which establish the basis for the loss computation below. Table 1. Distribution of the population and building inventory (residential only) in each of the six
Table 1. Distribution of the population and building inventory (residential only) in each of the si sectors of Bucharest. The available building database contained several parameters that could be used for th« subdivision into building classes: main construction material; building class; period o construction; height class; number of dwellings (ec. number of apartments or living units and number of occupants. The information given in the database was combined with thi experience of local engineers and provided basis for a building typology classificatior according to the main structural material so that seven “Bucharest’-specific buildin; typologies were initially defined (Table 2). These seven main residential typologies wer further subdivided into 31 model building types for which damage computations ar conducted and which establish the basis for the loss computation below. Table 1. Distribution of the population and building inventory (residential only) in each of the six
Table 2. Classification of the building typologies prevalent in the city of Bucharest and assignment with ‘HAZUS’ model building types (mbt). The seven main building typologies were assigned according to the descriptive keywords indicated in Table 2 and after consultation of local structural engineers. The highest number of buildings belongs to model building types M2, M3 and M5 which were mainly erected before 1970 (Figure 3). As Figure 3 illustrates, these buildings at the same time have relatively small building floor areas (in [m2]) which is caused by the fact that the majority is characterized by smaller story numbers and smaller plan dimensions. Consequently, buildings of M2, M3 and M5 typology represent 87% of the total number of individual buildings but only some 34% of the total building floor area.
Table 2. Classification of the building typologies prevalent in the city of Bucharest and assignment with ‘HAZUS’ model building types (mbt). The seven main building typologies were assigned according to the descriptive keywords indicated in Table 2 and after consultation of local structural engineers. The highest number of buildings belongs to model building types M2, M3 and M5 which were mainly erected before 1970 (Figure 3). As Figure 3 illustrates, these buildings at the same time have relatively small building floor areas (in [m2]) which is caused by the fact that the majority is characterized by smaller story numbers and smaller plan dimensions. Consequently, buildings of M2, M3 and M5 typology represent 87% of the total number of individual buildings but only some 34% of the total building floor area.
Table 4. Relation between height of the building and repair/replacement cost.
Table 4. Relation between height of the building and repair/replacement cost.
Table 3. Indoor occupancy numbers in the six city sectors during different times of day. There is at present no detailed economic model for Bucharest available that can be used to precisely determine the repair and replacement costs for different building types.. For the year 2006, the estimated average construction price (AP) per square meter in the city of Bucharest was estimated to 975 Euro. A more precise estimate as a function of building typology could not be elaborated, and hence a uniform replacement value of 975 Euto/m? was used as a best estimate average.
Table 3. Indoor occupancy numbers in the six city sectors during different times of day. There is at present no detailed economic model for Bucharest available that can be used to precisely determine the repair and replacement costs for different building types.. For the year 2006, the estimated average construction price (AP) per square meter in the city of Bucharest was estimated to 975 Euro. A more precise estimate as a function of building typology could not be elaborated, and hence a uniform replacement value of 975 Euto/m? was used as a best estimate average.
Table 6. Scenario Earthquakes with corresponding weight used for the seismic risk computation.
Table 6. Scenario Earthquakes with corresponding weight used for the seismic risk computation.
Table 5. Historical events in the Vrancea region which caused damage in the city of Bucharest (Oncescu ef a/., 1998; Mandrescu and Radulian, 1999). For the present study a repeat of the 1977 Vrancea earthquake is assumed to derive damage and loss estimated for Bucharest. The focal parameters (depth and magnitude) of this event delivered by different agencies showed significant variations. ISC Bulletin provided the highest magnitude of My 7.4..
Table 5. Historical events in the Vrancea region which caused damage in the city of Bucharest (Oncescu ef a/., 1998; Mandrescu and Radulian, 1999). For the present study a repeat of the 1977 Vrancea earthquake is assumed to derive damage and loss estimated for Bucharest. The focal parameters (depth and magnitude) of this event delivered by different agencies showed significant variations. ISC Bulletin provided the highest magnitude of My 7.4..
Figure 5. Elastic design spectra following the provisions of Eurocode 8 — Type 1 (M, > 5.5) for soil class C. Both spectra are scaled to the lowest and highest PGA values considered for the computation, respectively.
Figure 5. Elastic design spectra following the provisions of Eurocode 8 — Type 1 (M, > 5.5) for soil class C. Both spectra are scaled to the lowest and highest PGA values considered for the computation, respectively.
Figure 6. Damage in % of built area across city sectors and four dominant building typologies.
Figure 6. Damage in % of built area across city sectors and four dominant building typologies.
Table 7. Damage distribution in terms of % of built area for all building types in all in sectors for the CSM and MADRS methodologies respectively. See text for description on the CSM and MADRS methods. The table is cumulative over all 31 building typologies. Table 8. Damage distribution in terms of damaged buildings for all building types in all sectors for the CSM and MADRS methodologies respectively. See text for description on the CSM and MADRS methods. The table is cumulative over all 31 building typologies.
Table 7. Damage distribution in terms of % of built area for all building types in all in sectors for the CSM and MADRS methodologies respectively. See text for description on the CSM and MADRS methods. The table is cumulative over all 31 building typologies. Table 8. Damage distribution in terms of damaged buildings for all building types in all sectors for the CSM and MADRS methodologies respectively. See text for description on the CSM and MADRS methods. The table is cumulative over all 31 building typologies.
The differences in predicted damage exemplify the important and inherent uncertainty in risk computations even when using very similar methodologies. The MADRS methodology can be considered as a second generation CSM method, and as such should be initially considered as the best of the two methods.
The differences in predicted damage exemplify the important and inherent uncertainty in risk computations even when using very similar methodologies. The MADRS methodology can be considered as a second generation CSM method, and as such should be initially considered as the best of the two methods.
Figure 7. Median monetary loss for each of the Bucharest sectors. The economic losses obtained through the use of the MADRS method (10,001 + 2,266
Figure 7. Median monetary loss for each of the Bucharest sectors. The economic losses obtained through the use of the MADRS method (10,001 + 2,266
Figure 8. Human deaths in each Bucharest sector as computed with the CSM and MADR: methods (only median value is represented). When we compare these results with the fatalities of the 1977 Vrancea earthquake we observe that the CSM method yields human losses that are only slightly lower than the number reported from the 4 March 1977 earthquake (when 1424 people were reported killed in Bucharest city). It should be noted that the 4 March 1977 earthquake occurred at 19:21 GMT, comparing to 21:21 local time, which should be comparable to a night time scenatio. The reported human losses from the Vrancea earthquake are clearly within the confidence limits of the model results provided by both the CSM and the MADRS methods. However, since 1977 the population of Bucharest has increased dramatically, and as warned above the good correlation between historical and predicted deaths should not be over interpreted.
Figure 8. Human deaths in each Bucharest sector as computed with the CSM and MADR: methods (only median value is represented). When we compare these results with the fatalities of the 1977 Vrancea earthquake we observe that the CSM method yields human losses that are only slightly lower than the number reported from the 4 March 1977 earthquake (when 1424 people were reported killed in Bucharest city). It should be noted that the 4 March 1977 earthquake occurred at 19:21 GMT, comparing to 21:21 local time, which should be comparable to a night time scenatio. The reported human losses from the Vrancea earthquake are clearly within the confidence limits of the model results provided by both the CSM and the MADRS methods. However, since 1977 the population of Bucharest has increased dramatically, and as warned above the good correlation between historical and predicted deaths should not be over interpreted.