Paleosis Logo Small
Home

Regions

Region I:
The Lower Rhine Graben System
(Roer Valley Graben)

1. Introduction

Geological Setting

Modern Seismicity

2. Paleoseismological studies

2.1. The Feldbiss
Fault in Belgium

2.1.1. Introduction

2.1.2. Geomorphology

2.1.3. Site Selection

2.1.4 Geophysical prospecting results

2.1.5. Trench analysis

2.1.6. Preliminary
results

2.1.7. Upcoming investigations

Euro logo
PALEOSIS

1. Introduction

1.2. Modern Seismicity

The instrumental and historical seismic activity (Fig. 1) is not restricted to the Roer Graben and is unequally distributed over an active region west of the Roer Graben and a region with very low seismic activity in the eastern part of the Rhenish Massif. Most earthquakes are only moderate, with magnitudes generally less than M=4.

Among the most important recent seismic events (green circles), the Liège earthquake of November 8, 1983 (MS=4.6) occurred at the limit between the Brabant and the Ardenne Massifs, outside the graben, and had a dextral strike-slip mechanism along an ENE-WSW trending fault with a thrust component at a depth of 4-6 km. More recently, the Roermond earthquake of April 13, 1992 (MS=5.4) occurred along the Peel Boundary fault and showed a pure normal faulting mechanism along a NW-SE trending fault; it originated at the base of the brittle crust at a depth of 17 km (Camelbeeck and van Eck, 1994). Two other moderate earthquakes occurred this century in the Roer Graben: the Uden event of November 1932 (MS=4.7) and the Euskirchen earthquake of March 13, 1951 (MS=5.3).

Beginning from the XVII century, the historical seismicity catalog provides numerous data on the damage distribution and related effects (Alexandre, 1990; Alexandre and Vogt, 1994), allowing an estimation of seismic parameters. Within this epoch, five earthquakes with M > 5 affected the graben; among these, the Düren earthquake of February 18, 1756 with an attributed magnitude MW=5.5 was designated as the strongest. Nevertheless, this activity alone cannot account for the present-day and Holocene deformation rates. This is mainly because

  • the seismic activity is not restricted along a single fault but distributed along the 150 km long graben, and
  • no surface faulting was observed neither for the Roermond earthquake (MS=5.3) nor for any older historical seismic events.

The most important historical events are listed in Table 1.

DATE

LAT

LON

MS

Mest

I0

REFERENCE

13950611

50.6 N

6.3 E

    

VII

Alexandre (1994)

15040823

50.8 N

6.1 E

    

VII

Alexandre (1994)

16400404

50.8 N

6.1 E

    

VII

Vogt (1994)

16901218

50.8 N

6.1 E

    

VI-VII

-

16920908

50.6 N

5.8 E

  

5.5

VIII

Seimic Hazard Working Party (1993)

17551227

50.8 N

6.2 E

    

VII

Alexandre et Vogt (1994)

17560218

50.7 N

6.3 E

  

5.4

VIII

Seismic Hazard W.P. (1993),
Alexandre and Vogt (1994)

17600120

50.7 N

6.3 E

    

VII

Alexandre and Vogt (1994)

18280223

50.7 N

5.2 E

  

4.6

VII-VIII

Seis. Haz. W.P. (1993),
Ambraseys (1985b), Karnik (1969)

18731022

50.90 N

6.10 E

  

4.6

VII

Seis. Haz. W.P. (1993),
Ambraseys (1985b), Karnik (1969)

18780826

50.93 N

6.55 E

  

5.2

VIII

Seis. Haz. W.P. (1993),
Ambraseys (1985b), Karnik (1969)

19321120

51.71 N

5.61 E

4.7

  

VII

Ambraseys (1985a)

19510314

50.64 N

6.73 E

5.3

  

VII-VIII

Ambraseys (1985a)

19831108

50.63 N

5.53 E

4.5

  

VII

Ambraseys (1985a)

19920413

51.16 N

5.92 E

5.3

  

VII

Camelbeeck and van Eck (1994)

Mest : estimated magnitude from macroseismic informations;
I0 : maximal observed intensity (M.S.K. scale).

Table 1- Main historical earthquakes with estimated MS magnitude > 4.5 in the Lower Rhine Graben region.