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OTTIGNIES-LOUVAIN-LA-NEUVE (BE)

Earthquake8 August 2008

Magnitude
1.8ML
Depth
7.5km ± 1.9
Max. int.
2
Belgian time
19:52:022008-08-08
UTC
17:52:022008-08-08

Main parameters

Magnitude and intensity

Two numbers often confused, with the values of this earthquake and of the Observatory’s catalogue.

Preparing the animation…

1Magnitude: the size of the earthquake

The magnitude (ML 1.8) measures the size of the earthquake at its source, from the amplitude of the waves recorded by seismographs: a single value for the whole earthquake. Since 1985, 78 % of the 3,122 earthquakes with a magnitude in the Observatory’s catalogue have a smaller one.

Animation drawn from the page and the Observatory’s catalogue (tectonic earthquakes since 1985, ML or MW magnitudes); short descriptions of the European Macroseismic Scale EMS-98.

Date and time2008-08-08 17:52:02 UTC
2008-08-08 19:52:02 Belgian time
MagnitudeML 1.8
Epicentral coordinates50.641° N, 4.570° E
Uncertainty ± 1.3 km
Maximum intensity2
Depth of hypocenter7.5 ± 1.9 km
Event IDROB 3094

Data source : ROB (Royal Observatory of Belgium)
Last update : 2016-11-24 11:24:43 Belgian time

Location map

Where and when the earthquake began

The focus, the epicentre and their uncertainties, with this earthquake’s values.

Preparing the animation…

1Focus and epicentre

An earthquake starts at depth, at the focus (or hypocentre): here 7.5 km below the surface. The point on the surface right above it is the epicentre (50.641° N, 4.570° E), the one the map shows.

Values from the page and the Observatory’s catalogue (tectonic earthquakes since 1985).

  • Epicentre
  • Station that recorded the event

Macroseismic inquiry

How the macroseismic inquiry works

Using the answers to the “Did you feel an earthquake?” questionnaire for this earthquake.

Preparing the animation…

1Testimonies

34 answers to the online questionnaire were received for this earthquake, from 12 municipalities. Each dot is a municipality, larger when it has more answers; the farthest, BOUSSU, is 60 km from the epicentre, outside the frame.

Animation drawn from this earthquake’s answers, with the calculation of the page’s map and chart (ROB method).

Intensities derived from the answers to the online questionnaire “Did you feel an earthquake?”, grouped by municipality (former municipalities included). The map and the chart give the intensity of each municipality.

Answers
34
Municipalities
12
Farthest municipality
60km · BOUSSU
Countries
Belgium
Grouping
Show
Intensity of the municipality (CII)
  • I
  • II
  • III
  • IV
  • V
  • VI
  • VII+
Answers per municipality
  • 3–4
  • 5–9
  • 10–19
  • 20–49
  • ≥ 50
  • felt, fewer than 3 answers
  • Epicentre

Answers by intensity

IntensityAnswers
I11
II13
III9
IV1
Total34

Intensity against distance

  • Intensity of the municipality (CII)

Warning: the intensities derived from the inquiry are raw, unverified data.

Notes and method

Intensity of a municipality or a cell (CII, Community Internet Intensity) is computed as follows:

  • I if no answer reports that the earthquake was felt;
  • F earthquake felt, but fewer than 3 answers kept per municipality or cell;
  • II–IX computed from 3 answer(s) kept: CII = 3.40 ln(CWS) − 4.38 (Wald et al., 1999), applied to the weighted sum (CWS) of the mean indexes of the answers; at least II if felt, at most IX.

Answers kept (USGS method, as applied by the ROB): reliability of 80 or more, given on the ground floor up to the 4th floor (or unknown floor), without those more than two standard deviations from the mean. The “felt” index is weighted by the answer to “Did others nearby feel it?”.

Distribution by intensity: macroseismic intensity (MI) recorded for each answer.

Cells: 5 or 10 km squares of the Belgian Lambert 72 grid, each answer placed at its geocoded address or at the point it placed on the map, otherwise at the centre of its municipality. The positions of the answers are published only rounded to about 1 km, in “Arrival of the answers”. Grid cell method: Van Noten et al. (2017), Solid Earth 8, 453–477, doi:10.5194/se-8-453-2017.

Answers read on 2026-11-09 10:22.

Seismic activity in the area

Known earthquakes around the epicentre, from the catalogue of the Royal Observatory of Belgium.

Within 10 km of the epicentre

257 other earthquakes in the catalogue since 1953. 222 of them occurred after this one.

Latest earthquakes before this one

DatePlaceMagnitudeIntensityDistance km
2008-08-08OTTIGNIES-LOUVAIN-LA-NEUVE (BE)ML 1.724.4
2008-08-08OTTIGNIES-LOUVAIN-LA-NEUVE (BE)ML 1.621.9
2008-07-31CEROUX-MOUSTY (BE)ML 0.4–2.9
2008-07-25CEROUX-MOUSTY (BE)ML 0.2–1.7
2008-07-25CEROUX-MOUSTY (BE)ML 0.2–4.0

Largest known earthquakes

DatePlaceMagnitudeIntensityDistance km
1953-01-06COURT-SAINT-ETIENNEML 4.053.4
1953-08-28COURT-SAINT-ETIENNEML 3.663.4
1953-08-28COURT-SAINT-ETIENNEML 3.453.4
2008-07-13COURT-SAINT-ETIENNE (BE)ML 3.231.1
2009-03-03COURT-SAINT-ETIENNE (BE)ML 2.841.0

Municipality of Court-Saint-Etienne

230 other earthquakes in the catalogue since 1955. 208 of them occurred after this one.

Latest earthquakes before this one

DatePlaceMagnitudeIntensityDistance km
2008-07-25CEROUX-MOUSTY (BE)ML 0.2–1.7
2008-07-22COURT-SAINT-ETIENNE (BE)ML 0.3–2.0
2008-07-21COURT-SAINT-ETIENNE (BE)ML 0.5–1.0
2008-07-19OTTIGNIES-LOUVAIN-LA-NEUVE (BE)ML 0.4–0.7
2008-07-19MELLERY (BE)ML 0.0–3.4

Largest known earthquakes

DatePlaceMagnitudeIntensityDistance km
2008-07-13COURT-SAINT-ETIENNE (BE)ML 3.231.1
2009-03-03COURT-SAINT-ETIENNE (BE)ML 2.841.0
2008-09-13OTTIGNIES-LOUVAIN-LA-NEUVE (BE)ML 2.641.9
2009-12-26COURT-SAINT-ETIENNE (BE)ML 2.531.8
2008-12-20OTTIGNIES-LOUVAIN-LA-NEUVE (BE)ML 2.431.3
Notes and method

Tectonic and induced earthquakes from the Observatory’s catalogue, suspected ones included; quarry blasts, explosions and other events are not counted. Epicentral distances on the WGS84 ellipsoid.

Municipality: 2025 municipal boundaries (Statbel), applied to every earthquake, including those before the merger of municipalities. For an epicentre outside Belgium, only the circular area is given. Each earthquake’s name is the catalogue’s: it may refer to a place near the epicentre.

Magnitude: the one given on each earthquake’s page (ML preferably, otherwise MW or MS); magnitudes of different types are compared as they are.

The epicentres of historical earthquakes are only known to within a few kilometres, sometimes more: whether they fall in the area is indicative. Small earthquakes have only been recorded as the station network grew: the area’s older earthquakes are mostly the largest ones, and recent activity looks more frequent.

Arrival times at the stations

How is an earthquake located?

Using the P and S waves measured for this earthquake.

Preparing the animation…

1Two waves leave the focus

When the earthquake occurs, two waves leave the focus, 7.5 km deep. The P wave, the fastest, travels at about 5.4 km/s; the S wave at about 3.4 km/s. These are the average speeds that best match this earthquake’s measurements.

Animation drawn from the arrivals measured for this earthquake and the speeds of the chart; only stations within 120 km are shown, and the circles are drawn at the surface.

Each station first records the P wave, the fastest, then the S wave. The farther a station is from the epicentre, the later the waves reach it and the wider the gap between the two.

Stations
22
Epicentral distance
2.1 – 160.7km
Mean velocity, P wave
5.4km/s
Mean velocity, S wave
3.4km/s
  • P wave
  • S wave
  • Curve fitted to the measurements
Notes and method

Curves: travel time of a direct wave in a homogeneous medium. The velocity of each wave and an origin-time shift, common to both, are fitted to the measurements by least squares. Hypocenter at a depth of 7.5 km. P wave: 17 measurements, root-mean-square deviation 2.07 s. S wave: 15 measurements, root-mean-square deviation 0.55 s.

Stations farther than 120 km are left out of the fit: the first waves to reach them have travelled beneath the crust, through the mantle, where they propagate faster.

Table of measurements

Station measurements

P- and S-wave arrivals and ground displacement measured at each station. Click a column heading to change the order.

km°UTCUTCsnm
Belgian seismic network (Royal Observatory of Belgium)19 stations
OTTOttignies2.134017:52:04.26+1.56 s17:52:05.02+2.32 s0.76–
UCCBUccle22.831917:52:06.42+3.72 s17:52:08.80+6.10 s2.38323.0
UCCSUccle22.831917:52:06.52+3.82 s17:52:08.78+6.08 s2.26–
RQRRonquières24.726117:52:07.13+4.43 s17:52:09.59+6.89 s2.4633.1
SNFSeneffe24.923517:52:07.30+4.60 s17:52:10.11+7.41 s2.8147.0
SKQSteenkerque34.727217:52:08.60+5.90 s17:52:13.51+10.81 s4.91–
MRDMaredsous40.316017:52:10.34+7.64 s17:52:15.12+12.42 s4.78–
CTHCouthuin40.710717:52:09.55+6.85 s–––
GESGesves46.412817:52:10.93+8.23 s17:52:16.60+13.90 s5.6727.1
BOUBougnies52.523817:52:11.81+9.11 s17:52:18.86+16.16 s7.0522.4
CLAClavier57.511517:52:12.82+10.12 s17:52:19.24+16.54 s6.42–
DOUDourbes60.817817:52:13.58+10.88 s17:52:20.75+18.05 s7.17–
RCHRochefort71.513917:52:15.29+12.59 s17:52:22.71+20.01 s7.42–
MOLAMol73.32917:52:24.20+21.50 s17:52:24.74+22.04 s0.54–
MEMSMembach101.99117:52:19.73+17.03 s17:52:32.51+29.81 s12.78–
MEMHMembach101.99117:52:19.90+17.20 s–––
KLBKalborn124.911817:52:24.20+21.50 s17:52:37.42+34.72 s13.22–
VIAVianden140.312317:52:23.92+21.22 s17:52:42.18+39.48 s18.2611.5
WLFWalferdange156.813317:52:29.20+26.50 s17:52:46.02+43.32 s16.82–
Bensberg seismic network (University of Cologne, Germany)3 stations
DREDreilägerbach117.68817:52:23.67+20.97 s17:52:38.09+35.39 s14.42–
KLLKalltalsperre123.18917:52:24.10+21.40 s17:52:39.36+36.66 s15.26–
STBSteinbachtalsperre160.79117:52:29.73+27.03 s17:52:48.74+46.04 s19.01–
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