SCHWEICH, STADT (DE)

Earthquake30 July 1997

Magnitude
–
Depth
14.7km ± 1.7
Belgian time
02:40:211997-07-30
UTC
00:40:211997-07-30

Main parameters

Date and time1997-07-30 00:40:21 UTC
1997-07-30 02:40:21 Belgian time
Magnitude–
Epicentral coordinates49.830° N, 6.762° E
Uncertainty ± 1.3 km
Depth of hypocenter14.7 ± 1.7 km
Event IDROB 2583

Data source : ROB (Royal Observatory of Belgium)
Last update : 2009-05-30 18:17:43 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 14.7 km below the surface. The point on the surface right above it is the epicentre (49.830° N, 6.762° 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

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

No other earthquake known in the catalogue.

Nearest beyond 10 km

DatePlaceMagnitudeIntensityDistance km
2023-01-06LORSCHEID (DE)ML 1.4–10.7
2016-09-01RIVERIS (DE)ML 1.1–11.1
2009-09-07LORSCHEID (DE)ML 1.2–12.0
2021-06-07FARSCHWEILER (DE)sequence of 2ML 1.5–12.6
2014-05-17BONERATH (DE)sequence of 3ML 1.4–14.1
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

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, 15 km deep. The P wave, the fastest, travels at about 5.9 km/s; the S wave at about 3.5 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
13
Epicentral distance
25.8 – 158.2km
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 14.7 km. P wave: 9 measurements, root-mean-square deviation 0.25 s. S wave: 8 measurements, root-mean-square deviation 0.52 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°UTCUTCs
Belgian seismic network (Royal Observatory of Belgium)6 stations
VIAVianden41.928600:40:29.00+7.51 s00:40:33.85+12.36 s4.85
WLFWalferdange47.724800:40:29.59+8.10 s00:40:36.49+15.00 s6.90
MEUMeuville94.931200:40:37.34+15.85 s00:40:48.94+27.45 s11.60
MEMSMembach102.032900:40:38.76+17.27 s00:40:50.92+29.43 s12.16
CTHCouthuin140.930400:40:44.53+23.04 s00:41:00.65+39.16 s16.12
DOUDourbes158.2282–00:41:05.62+44.13 s–
Network FR2 stations
RUPRuppelstein25.812300:40:26.30+4.81 s00:40:29.40+7.91 s3.10
ABHAlteburg56.88400:40:31.20+9.71 s––
Dutch seismic network (KNMI)1 station
HGNHeimansgroeve119.633100:40:41.40+19.91 s00:40:55.16+33.67 s13.76
Network FBB1 station
KTDKALMITSTRASSE-ALSTERWEILER111.112000:40:40.80+19.31 s00:40:54.10+32.61 s13.30
German Regional Seismic Network (BGR, Germany)1 station
TNSTaunus Observatorium Kleiner Feldberg128.46900:40:41.90+20.41 s00:40:57.70+36.21 s15.80
Network JCK1 station
GSHGrosshau104.434500:40:38.80+17.31 s00:40:52.20+30.71 s13.40
Network LDG1 station
GIVFGivet142.328300:40:47.70+26.21 s00:41:00.30+38.81 s12.60
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