TOURNAI (BE)
Quarry blast6 December 2021
- Magnitude
- 1.2ML
- Depth
- –
- Belgian time
- 13:00:052021-12-06
- UTC
- 12:00:052021-12-06
Main parameters
| Date and time | 2021-12-06 12:00:05 UTC 2021-12-06 13:00:05 Belgian time |
|---|---|
| Magnitude | ML 1.2 |
| Epicentral coordinates | 50.660° N, 3.462° E Uncertainty ± 10.9 km |
| Event ID | ROB 14940 |
Data source : ROB (Royal Observatory of Belgium)
Last update : 2021-12-06 13:53:10 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
- 8
- Epicentral distance
- 27.6 – 137.5km
- 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: 6 measurements, root-mean-square deviation 0.70 s. S wave: 4 measurements, root-mean-square deviation 0.93 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)8 stations | |||||
| LESLessines | 27.6 | 78 | 12:00:11.62+5.71 s | 12:00:14.46+8.55 s | 2.84 |
| SKQSteenkerque | 43.8 | 91 | 12:00:12.49+6.58 s | 12:00:18.09+12.18 s | 5.60 |
| BRQBracquegnies | 51.7 | 112 | 12:00:15.11+9.20 s | – | – |
| RQRRonquières | 54.3 | 96 | 12:00:15.89+9.98 s | – | – |
| TGATangissart | 75.3 | 94 | 12:00:18.52+12.61 s | 12:00:28.57+22.66 s | 10.05 |
| DOUDourbes | 102.2 | 127 | 12:00:23.43+17.52 s | 12:00:38.93+33.02 s | 15.50 |
| CLAClavier | 133.2 | 101 | 12:00:28.81+22.90 s | 12:00:43.60+37.69 s | 14.79 |
| RCHRochefort | 137.5 | 113 | 12:00:25.45+19.54 s | 12:00:46.11+40.20 s | 20.66 |