TOURNAI (BE)
Quarry blast21 April 2021
- Magnitude
- 1.8ML
- Depth
- –
- Belgian time
- 13:00:322021-04-21
- UTC
- 11:00:322021-04-21
Main parameters
| Date and time | 2021-04-21 11:00:32 UTC 2021-04-21 13:00:32 Belgian time |
|---|---|
| Magnitude | ML 1.8 |
| Epicentral coordinates | 50.642° N, 3.471° E Uncertainty ± 13.3 km |
| Event ID | ROB 13230 |
Data source : ROB (Royal Observatory of Belgium)
Last update : 2021-04-23 18:01:36 Belgian time
Location map
- Epicentre
- Station that recorded the event
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
- 11
- Epicentral distance
- 27.4 – 136.1km
- Mean velocity, P wave
- 5.6km/s
- Mean velocity, S wave
- 3.2km/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. Depth not determined: hypocenter placed at the surface for the calculation. P wave: 9 measurements, root-mean-square deviation 0.64 s. S wave: 6 measurements, root-mean-square deviation 0.50 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 | |
|---|---|---|---|---|---|
| Belgian seismic network (Royal Observatory of Belgium)11 stations | |||||
| LESLessines | 27.4 | 74 | 11:00:38.02+5.16 s | 11:00:41.94+9.08 s | 3.92 |
| SKQSteenkerque | 43.1 | 89 | 11:00:40.06+7.20 s | 11:00:46.21+13.35 s | 6.15 |
| BOUBougnies | 43.9 | 130 | 11:00:40.40+7.54 s | 11:00:47.01+14.15 s | 6.61 |
| BRQBracquegnies | 50.4 | 111 | 11:00:41.31+8.45 s | – | – |
| RQRRonquières | 53.5 | 94 | 11:00:41.97+9.11 s | – | – |
| SNFSeneffe | 59.4 | 104 | 11:00:42.45+9.59 s | – | – |
| MRDMaredsous | 99.6 | 112 | 11:00:51.98+19.12 s | 11:01:04.16+31.30 s | 12.18 |
| DOUDourbes | 100.5 | 127 | 11:00:50.36+17.50 s | 11:01:03.35+30.49 s | 12.99 |
| GESGesves | 118.2 | 103 | 11:00:54.03+21.17 s | 11:01:09.32+36.46 s | 15.29 |
| CLAClavier | 132.2 | 100 | 11:00:55.97+23.11 s | 11:01:13.43+40.57 s | 17.46 |
| RCHRochefort | 136.1 | 113 | 11:00:55.39+22.53 s | 11:01:12.41+39.55 s | 17.02 |