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Seismic zones map - Belgium

What are the Belgian seismic zones ?

In Belgium, the division is specified in the national annex to Eurocode 8 (The map below was created from this data). The Belgian area is divided into five seismic zones identified from 0 to 4.

Zone 0 1 2 3 4
Seismicity agr - 0.39m/s2 0.59m/s2 0.78m/s2 0.98m/s2
Eurocodes - Seismic zones map - Belgium (2011-2021) Seismic zoning of Belgium (2011-2021)

Is my new building concerned ?

In Belgian regulations, the zones considered to be zones with very low seismicity are the zones for which the product agS (with ag = γI . agr) does not exceed 0.06g (0.59m/s2). Here is the summary:
Zone/Ground type A B C D E
Zone 0 No
Zone 1 No Yes (except I and II) Yes (except I)
Zone 2 Yes (except I and II) Yes
Zone 3 Yes
Zone 4 Yes

The soil factor S is depending of the stratigraphic profile of the ground and the type of recommended elastic response spectra with respect to the surface-wave magnitude.

Ground type Description of stratigraphic profile S parameter for spectrum type 2
A Rock or other rock-like geological formation, including at most 5m of weaker material at the surface. 1,0
B Deposits of very dense sand, gravel, or very stiff clay, at least several tens of metres in thickness, characterised by a gradual increase of mechanical properties with depth. 1,35
C Deep deposits of dense or medium-dense sand, gravel or stiff clay with thickness from several tens to many hundreds of metres. 1,5
D Deposits of loose-to-medium cohesionless soil (with or without some soft cohesive layers), or of predominantly soft-to-firm cohesive soil. 1,8
E A soil profile consisting of a surface alluvium layer with Vs values of type C or D and thickness varying between about 5m and 20m, underlain by stiffer material with Vs>800m/s. 1,6
Buildings are classified in 4 importance classes, depending on the consequences of collapse for human life, on their importance for public safety and civil protection in the immediate post-earthquake period, and on the social and economic consequences of collapse.
Each importance class is attached to an importance factor γI.
Importance class Buildings γ I
I Buildings of minor importance for public safety, e.g. agricultural buildings, etc. 0.8
II Ordinary buildings, not belonging in the other categories. 1.0
III Buildings whose seismic resistance is of importance in view of the consequences associated with a collapse, e.g. schools, assembly halls, cultural institutions etc. 1.2
IV Buildings whose integrity during earthquakes is of vital importance for civil protection, e.g. hospitals, fire stations, power plants, etc. 1.4
NOTE: Importance classes I, II and III or IV correspond roughly to consequences classes CC1, CC2 and CC3, respectively, defined in the Annex B to Eurocode 0.

Example of results given by the software

See the features of Eurocodes Zoning for seismic analysis in Belgium
Available in English/French, otherwise «Google Translate»!

B1 - Localization

Belgian flag
4.9053° , 50.2445°
688279m , 603864m
Large map
Simple map
Rondchêne, 5500 Dinant, Wallonie

B2 - Elevations

Elevation map to calculate orography factor
Coordinates 4.9013°, 50.241° 4.9044°, 50.2436°
Elevations 96m 189m
Obstacle effective height H 93m
Slope actual length Lu / Ld 361.4m
Slope angle Φ 25.7%
Horizontal distance site/top x 121.2m
Elevation at the place of construction 197m

B3 - Building

common building with floors (apartments and/or office spaces)

B4 - Terrain categories

Terrain map
Sectors 1 2 3 4
Categories II II III II
Radius R of the angular sector : 300m

C1 - Snow NBN EN 1991-1-3 ANB (october 2007)

Belgium (sk,0 = 0.5kN/m2)
Dinant, Namur
sk,197m = 0.613 kN/m2

s100ans = 0.695 kN/m2

C2 - Wind NBN EN 1991-1-4 ANB (december 2010)

24 m/s
Dinant, Namur
Sectors 1 2 3 4
Sector definition from 350° to 80° from 80° to 170° from 170° to 260° from 260° to 350°
Fundamental value of the basic wind velocity vb,0 24.0m/s
Shape parameter K 0.2
Exponent n 0.5
Annual probability of exceedence p 0.01
Probability factor cprob 1.038
Directional factor cdir 1.0 0.983 1.0 1.0
Basic wind velocity vb 24.9m/s 24.5m/s 24.9m/s 24.9m/s
Reference roughness length z0,II 0.05m
Roughness length z0 0.05m 0.05m 0.3m 0.05m
Terrain factor kr 0.19 0.19 0.215 0.19
Height above ground z 7.0m
Minimum height zmin 2.0m 2.0m 5.0m 2.0m
Roughness factor cr(z) 0.939 0.939 0.678 0.939
Obstacle type cliffs
Exposure type - - downwind -
Factor depending on the type and dimensions of the obstacle s max 0.0 0.0 0.598 0.0
Orography factor* co(z) 1.0 1.0 1.308 1.0
Mean wind velocity vm(z) 23.4m/s 23.0m/s 22.1m/s 23.4m/s
Turbulence factor kl 0.995 0.995 1.247 0.995
Standard deviation of the turbulence σv 4.713m/s 4.634m/s 6.696m/s 4.713m/s
Turbulence intensity Iv(z) 0.201 0.201 0.303 0.201
Air density ρ 1.25kg/m3
Exposure factor ce(z) 2.124 2.124 2.456 2.124
Peak velocity pressure qp(z) 824.7N/m2 797.5N/m2 953.3N/m2 824.7N/m2
Peak wind velocity for Serviceability Limit States vp(z),SLS 130.8km/h 128.6km/h 140.6km/h 130.8km/h
Peak wind velocity for Ultimate Limit States vp(z),ULS 160.2km/h 157.5km/h 172.2km/h 160.2km/h
* The orography factor is calculated for a well individualized obstacle (an emergent zone compared to a general ground without marked relief)

C3 - Seism NBN EN 1998-1 ANB (october 2011)

1 (0.39m/s2)
Dinant, Namur
A seismic analysis may be required for this building.