『Abstract
Tectonic motion rates of individual faults and regional deformation
in an intraplate setting are estimated, based on the analysis
of ten yearly surveys of a regional levelling network in NE Ardenne
(W Europe). Owing to the frequency and number of measurement epochs,
much greater than in classical comparisons of general surveys,
the tectonic and near-surface components of ground motion are
clearly separated. The marked temporal variability in ground motion
strongly depends on the amount of precipitation fallen during
the six months preceding each survey and the subsequent drying
off of the subsoil at the time of the surveys. Moreover, the ground
response to this influence varies from place to place, leading
to high differential movements at the local scale. Taking into
account the percentage of surveyed faults which moved tectonically
during the time of the study, I calculate fault motion rates of
0.06-0.09 mm/yr, similar to geological rates. Moreover, the data
indicate that one way for intraplate normal faults to accommodate
tectonic strain aseismically is intermittent fault creep, with
short episodes of a few mm displacement separated by many year-long
time intervals of fault quiescence. A flexural deformation shows
the superposition of a tilt event on a trend corresponding to
a tilt rate of 0.16 μrad/yr for a 2.8-km-long segment.
Keywords: Crustal motion; Intraplate; Levelling; Hydrological
factor; Geodetic rate; Fault creep』
1. Introduction
『
| 地域 |
測地学的 （mm/年） |
地質学的 〔1〜0×100万年前〕 （mm/年） |
引用文献 |
| 広域的運動 | |||
| Eifel（D） | 1.6 | 0.25 | Malzer〔aの頭に¨〕 et al.(1983)ほか |
| S Limburg（NL） | 0.8 | 0.06 | Kooi et al.(1998)ほか |
| Upper Rhine graben〔地溝〕（F） | ＞1.0 | Liaghat et al.(1998) | |
| W Brittany（F） | 1.0 | 〜0.1 | Lenotre〔oの頭に＾〕 et al.(1999)ほか |
| NE Spain（SP） | 0.8 | Gimenez et al.(1996) | |
| Ardenne（B） | 1.3 | 〜0.1 | Pissart and Lambot(1989)ほか |
| 断層運動 | |||
| Roer graben（NL） | 1.5 | 0.07〜0.1 | van den Berg(1994)ほか |
| Upper Rhine graben（CH） | 0.2 | Meghraoui et al.(2001) | |
| E Betics（SP） | 0.9〜2.0 | 0.08〜0.15 | Gimenez et al.(2000)ほか |
2. Geological setting
3. The data
4. Near-surface origin of ground motion
5. Vertical motions of tectonic origin and geodetic motion rate
6. Nature of the observed fault motions
Acknowledgements
References