Newest results obtained in studying the Fennoscandian land uplift phenomenon

Kakkuri, Juhani

doi:10.1016/0040-1951(86)90122-8

Cited by 8 publications

(3 citation statements)

References 2 publications

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“…The Fennoscandian (Norway, Finland, Sweden) part of this area is characterized by thick lithosphere (110--170 km) and low heat flow (<50 mW/m2). It is presently undergoing recent crustal uplift (maximum uplift 1 m/100 years at the center of the area in the northern Baltic Sea [Kakkuri, 1986]) as a result of postglacial rebound [Bakkelid, 1986;Ekmann, 1977]. The shape of the postglacial land uplift is displayed in Figure 8 We conclude, similar to Stephansson [1988], that a combination of plate boundary forces with local sources (e.g., flexural stresses) are responsible for the stress field in Northern Europe.…”

Section: Northern European Stress Provincementioning

confidence: 99%

Regional patterns of tectonic stress in Europe

Müller¹,

Zoback²,

Fuchs³

et al. 1992

J. Geophys. Res.

406

219

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Nearly 1500 stress orientation determinations are now available for Europe. The data come from earthquake focal mechanisms, overcoring measurements, well bore breakouts, hydraulic fracturing measurements, and young fault slip studies and sample the stress field from the surface to seismogenic depths. Three distinct regional patterns of maximum compressive horizontal stress (SHmax) orientation can be defined from these data: a consistent NW to NNW SHmax stress orientation in western Europe; a WNW‐ESE SHmax orientation in Scandinavia, similar to western Europe but with a larger variability of SHmax orientations; and a consistent E‐W SHmax orientation and N‐S extension in the Aegean Sea and western Anatolia. The different stress fields can be attributed to plate‐driving forces acting on the boundaries of the Eurasian plate, locally modified by lithospheric properties in different regions. On average, the orientation of maximum stress in western Europe is subparallel to the direction of relative plate motion between Africa and Europe and is rotated 17° clockwise from the direction of absolute plate motion. The uniformly oriented stress field in western Europe coincides with thin to medium lithospheric thickness (approximately 50–90 km) and high heat flow values (>80 m W/m2). In western Europe a predominance of strike‐slip focal mechanisms implies that the intermediate principal stress is vertical. The more irregular horizontal stress orientations in Scandinavia coincide with thick continental lithosphere (110–170 km) and low heat flow (<50 m W/m2). The cold thick lithosphere in this region may result in lower mean stresses associated with far‐field tectonic forces and allow the stress field to be more easily perturbed by local effects such as déglaciation flexure and topography. The stress field of the Aegean Sea and western Anatolia is consistent with N‐S extension in a back arc setting behind the Hellenic trench subduction zone. The stress field is influenced in places by regional geologic structures, e.g., in the Western Alps, where SHmax directions show a slight tendency toward a radial stress pattern. Not all major geologic structures, however, appear to affect the SHmax orientation, e.g., in the vicinity of the Rhine rift system horizontal stress orientations are continuous.

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Section: Northern European Stress Provincementioning

confidence: 99%

Regional patterns of tectonic stress in Europe

Müller¹,

Zoback²,

Fuchs³

et al. 1992

J. Geophys. Res.

406

219

View full text Add to dashboard Cite

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“…When geoid heights are known, the values of vertical displacements can be obtained with the following equation (Figure 3 With this reasoning, we assume that ground subsidence affecting only some near-surface strata has no effect on geoid height N. This is a reasonable simplification: even in the Fennoscandinavian uplift, which expresses a large-scale effect in both space (mantle doming over a region of 1000 -2000 km) and in time (thousands of years), the rate of change in geoid height is one order of magnitude smaller than the rate of change in topography [64].…”

Section: The Methodologymentioning

confidence: 99%

Estimation of Subsidence in Po Delta Area (Northern Italy) by Integration of GPS Data, High-Precision Leveling and Archival Orthometric Elevations

Fabris

Achilli

Menin

2014

IJG

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Subsidence in a deformation area can be measured in various ways, examples being conventional high-precision leveling, differential InSAR and multi-temporal GPS surveys. Integration of methods can improve results, and is crucial to extract high-precision data. In particular, orthometric and ellipsoid elevations, surveyed at different moments in time, can be compared to yield information on vertical movements when geoid anomalies are known. However, a data checking procedure must be applied if archival orthometric elevations are used, because long-term measurements for many historical benchmarks may have been lost and/or replaced with other points, but at different elevations. This type of checking can be carried out over an area without gravimetric anomalies by modeling geoid undulations and vertical displacements in the time-span used for analysis, excluding points with anomalous values. This procedure was tested and applied in the Po Delta area (northern Italy), historically subject to high subsidence rates: the leveling benchmarks of 1983 were measured with the GPS technique in 2008. After checking of archival data and transformation from ellipsoid to orthometric elevations, comparisons of the same points and interpolations on the study area provided a subsidence map for the 1983-2008 period.

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“…The dynamic relationship between land uplift and change in gravity leads to a static relationship between the remaining land uplift and the local geoid depression (Ekman 1992). A negative geoid anomaly or geoidal depression of 8–10 m in depth, being deepest near the centre of the fastest uplift, has been observed after removing a regional trend from the geoid (Bjerhammar 1980; Kakkuri 1986). Identical results, as shown in Fig.…”

Section: Introductionmentioning

confidence: 99%

Structural effects of the crust on the geoid modelled using deep seismic sounding interpretations

Kakkuri

Wang

1998

Geophys. J. Int.

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According to the theory of isostasy, the Earth has a tendency to deform its surface in order to reach an equilibrium state. The land‐uplift phenomenon in the area of the Fennoscandian Shield is thought to be a process of this kind. The geoid, as an equipotential surface of the Earth’s gravity field, contains information on how much the Earth’s surface departs from the equilibrium state. In order to study the isostatic process through geoidal undulations, the structural effects of the crust on the geoid have to be investigated. The structure of the crust of the Fennoscandian Shield has been extensively explored by means of deep seismic sounding (DSS). The data obtained from DSS are used to construct a 3‐D seismic‐velocity structure model of the area’s crust. The velocity model is converted to a 3‐D density model using the empirical relationship that holds between seismic velocities and crustal mass densities. Structural effects are then estimated from the 3‐D density model. The structural effects computed from the crustal model show that the mass deficiency of the crust in Fennoscandia has caused a geoidal depression twice as deep as that observed from the gravimetric geoid. It proves again that the crust has been isostatically compensated by the upper mantle. In other words, an anomalously high‐density upper mantle must exist beneath Fennoscandia.

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Newest results obtained in studying the Fennoscandian land uplift phenomenon

Cited by 8 publications

References 2 publications

Regional patterns of tectonic stress in Europe

Regional patterns of tectonic stress in Europe

Estimation of Subsidence in Po Delta Area (Northern Italy) by Integration of GPS Data, High-Precision Leveling and Archival Orthometric Elevations

Structural effects of the crust on the geoid modelled using deep seismic sounding interpretations

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