VELDEGEM (BE)
Earthquake2 August 2011
- Magnitude
- 2.4ML
- Depth
- 6.9km ± 3.2
- Max. int.
- 3
- Belgian time
- 20:37:082011-08-02
- UTC
- 18:37:082011-08-02
Main parameters
| Date and time | 2011-08-02 18:37:08 UTC 2011-08-02 20:37:08 Belgian time |
|---|---|
| Magnitude | ML 2.4 |
| Epicentral coordinates | 51.074° N, 3.146° E Uncertainty ± 1.6 km |
| Maximum intensity | 3 |
| Depth of hypocenter | 6.9 ± 3.2 km |
| Event ID | ROB 4565 |
Data source : ROB (Royal Observatory of Belgium)
Last update : 2016-11-24 10:19:58 Belgian time
Location map
- Epicentre
- Station that recorded the event
Macroseismic inquiry
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
- 575
- Municipalities
- 36
- Farthest municipality
- 328km · TYNAARLO
- Countries
- Belgium, Netherlands
- I
- II
- III
- IV
- V
- VI
- VII+
- 3–4
- 5–9
- 10–19
- 20–49
- ≥ 50
- felt, fewer than 3 answers
- Epicentre
Answers by intensity
| Intensity | Answers | |
|---|---|---|
| I | 162 | |
| II | 108 | |
| III | 228 | |
| IV | 73 | |
| V | 4 | |
| Total | 575 |
Intensity against distance
- Intensity of the municipality (CII)
- Mean of the municipalities per distance bin (± 1 standard deviation)
Arrival of the answers
All564 of 567 answers (99%)
- Answers at the same position (rounded to about 1 km):
- 1
- 10
- 50
- Epicentre
27 answers after +2 d, outside the chart.
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.
Arrival of the answers: time each answer of reliability 80 or more was sent, duplicates removed; position rounded to 0.01° (about 1 km), geocoded or otherwise at the centre of the municipality, where several answers may therefore pile up. Answers without a usable sending time or position, not shown: 3.
Answers without a known municipality, left out of the map and the chart: 3.
Answers read on 2026-11-09 10:08.
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
One other earthquake in the catalogue, in 1933. By magnitude, it is the 2nd largest of the 2 earthquakes of known magnitude in the area.
Latest earthquakes before this one
| Date | Place | Magnitude | Intensity | Distance km |
|---|---|---|---|---|
| 1933-03-23 | DIKSMUIDE | MWH 3.6 | 5 | 8.3 |
Largest known earthquakes
| Date | Place | Magnitude | Intensity | Distance km |
|---|---|---|---|---|
| 1933-03-23 | DIKSMUIDE | MWH 3.6 | 5 | 8.3 |
| 2011-08-02 | This earthquake | ML 2.4 | 3 | – |
Nearest beyond 10 km
| Date | Place | Magnitude | Intensity | Distance km |
|---|---|---|---|---|
| 2026-10-07 | RUISELEDE (BE)sequence of 2 | ML 1.9 | – | 14.8 |
| 1968-12-27 | DE PANNE-KOKSIJDE | ML 2.5 | 5 | 37.2 |
| 1938-06-12 | ZULZICH-NUKERKEsequence of 7 | ML 4.5 | 5 | 44.7 |
| 1942-06-17 | ZULZICH-NUKERKE | – | – | 44.7 |
| 2014-07-17 | North Seainduced | ML 2.5 | – | 45.7 |
Municipality of Torhout
No other earthquake known in the catalogue.
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.
When the area holds fewer than 5 other earthquakes, the nearest ones beyond 10 km are listed too, up to 100 km. Sequences (aftershocks, swarms) take a single row there, that of their largest earthquake: an earthquake joins a sequence if it occurs at most 7 days after the previous one and within 5 km of the first.
Arrival times at the stations
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
- 15
- Epicentral distance
- 18.6 – 236.2km
- Mean velocity, P wave
- 5.9km/s
- Mean velocity, S wave
- 3.5km/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 6.9 km. P wave: 7 measurements, root-mean-square deviation 0.50 s. S wave: 7 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.
Station measurements
P- and S-wave arrivals and ground displacement measured at each station. Click a column heading to change the order.
| km | ° | UTC | UTC | s | nm | |
|---|---|---|---|---|---|---|
| Belgian seismic network (Royal Observatory of Belgium)14 stations | ||||||
| ZEVZevekote | 18.6 | 292 | 18:37:12.04+3.35 s | 18:37:14.78+6.09 s | 2.74 | – |
| OSTBOostende | 23.3 | 322 | 18:37:12.66+3.97 s | 18:37:15.27+6.58 s | 2.61 | 216.2 |
| SKQSteenkerque | 81.0 | 125 | 18:37:22.60+13.91 s | 18:37:31.94+23.25 s | 9.34 | 343.9 |
| UCCSUccle | 90.8 | 109 | 18:37:23.50+14.81 s | 18:37:33.95+25.26 s | 10.45 | – |
| RQRRonquières | 92.1 | 124 | 18:37:24.29+15.60 s | 18:37:34.67+25.98 s | 10.38 | – |
| BOUBougnies | 94.8 | 143 | 18:37:25.92+17.23 s | 18:37:36.83+28.14 s | 10.91 | – |
| DSLBDessel | 135.4 | 82 | 18:37:31.30+22.61 s | 18:37:47.91+39.22 s | 16.61 | – |
| MRDMaredsous | 143.2 | 126 | 18:37:33.09+24.40 s | 18:37:49.87+41.18 s | 16.78 | – |
| DOUDourbes | 149.7 | 136 | 18:37:33.36+24.67 s | 18:37:51.36+42.67 s | 18.00 | 32.5 |
| GESGesves | 157.0 | 118 | 18:37:34.06+25.37 s | – | – | – |
| CLAClavier | 168.7 | 115 | 18:37:35.56+26.87 s | 18:37:55.37+46.68 s | 19.81 | 19.1 |
| MEMHMembach | 208.3 | 103 | 18:37:40.65+31.96 s | – | – | – |
| MEMSMembach | 208.3 | 103 | 18:37:40.67+31.98 s | – | – | – |
| KLBKalborn | 236.2 | 116 | 18:37:44.45+35.76 s | – | – | – |
| Network PSNT1 station | ||||||
| OOSOostburg | 37.2 | 40 | 18:37:15.57+6.88 s | 18:37:19.92+11.23 s | 4.35 | – |