Seismotektonische Traverse von der Nordsee bis zum Apennin

Ahorner, L.; Murawski, Hans; Schneider, G.

doi:10.1007/bf01820898

Cited by 44 publications

(14 citation statements)

References 24 publications

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“…Color code shows the original data; contour lines show the result of low‐pass filtering (cutoff wavelength 96 km) in order to enhance deep structures. (d) Moho fragmentation superimposed on digital terrain model, major faults, seismicity (NEIC, 1973–2008) and representative focal plane solutions [ Ahorner et al , 1972; Delise , 2007; Drimmel and Trapp , 1975; Gangl , 1975; Herak et al , 1995; Müller , 1977; Poljak et al , 2000; Reinecker and Lenhardt , 1999; Reiter et al , 2005; Renner and Slejko , 1994; Ritsema , 1974; Willingshofer and Cloetingh , 2003]. (e) Geodetic data of uplift/subsidence [ Höggerl , 2001] and horizontal displacement [ Grenerczy and Kenyeres , 2006; Weber et al , 2006].…”

Section: Plate Boundaries and Moho Fragmentationmentioning

confidence: 99%

Crustal structure and active tectonics in the Eastern Alps

et al. 2010

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[1] During the last decade, a series of controlled source seismic experiments brought new insight into the crustal and lithospheric structure of the Eastern Alps and their adjacent tectonic provinces. A fragmentation of the lithosphere into three blocks, Europe (EU), Adria (AD), and the new Pannonian fragment (PA), was interpreted and a triple junction was inferred. The goal of this study has been to relate these deep crustal structures to active tectonics. We used elastic plate modeling to reconsider the Moho fragmentation. We interpret subduction of EU below AD and PA from north to south and underthusting of AD mantle below PA from southwest to northeast. The Moho fragmentation correlates well with major upper crustal structures and is supported by gravity, seismic, and geodetic data. An analysis of crustal thickening suggests that active convergence is associated with continued thrusting and lateral extrusion in the central Eastern Alps and thickening of the Adriatic indenter under the Southern Alps. According to the velocity relations at the triple junction, PA moves relative to EU and AD along ENE and SE striking faults, mainly by strike slip. An eastward directed extensional component is compensated by the lateral extrusion of the central Eastern Alps. The Periadriatic (Insubric) line east of the triple junction and the mid-Hungarian fault zone have relatively recently lost their role as first-order active structures. We favor the idea that the Pannonian fragment and the TISZA block merged to a "soft" microplate surrounded by the Eastern and Southern Alpine, Carpathian, and Dinaric orogens. Citation: Brückl, E.,

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Section: Plate Boundaries and Moho Fragmentationmentioning

confidence: 99%

Crustal structure and active tectonics in the Eastern Alps

et al. 2010

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“…In the whole belt destructive earthquakes could potentially take place, particularly in the Valais in Switzerland, the Briançonnais and Provence in France, or Piedmont in Italy; however, some areas seem to be almost free of seismic activity (Ticino area, Switzerland; Vercors range, France). The first seismotectonic studies showed a radial fan for the P-axes around the Western Alpine Arc (Ahorner et al 1972;Fréchet 1978;Pavoni 1980a, b;Ménard 1988). By the end of the 1990s, an extensional regime was recognized in the internal zones of the belt, but locally also in some areas situated in the external zones (Maurer et al 1997;Baroux et al 2001;Kastrup et al 2004) (Fig.…”

Section: Alpine Neotectonics Inferred From Earthquake Analysis and Sumentioning

confidence: 99%

Extensional neotectonics around the bend of the Western/Central Alps: an overview

Sue

Delacou

Champagnac

et al. 2007

Int J Earth Sci (Geol Rundsch)

126

150

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The Western Alps' active tectonics is characterized by ongoing widespread extension in the highest parts of the belt and transpressive/compressive tectonics along its borders. We examine these contrasting tectonic regimes using a multidisciplinary approach including seismotectonics, numerical modeling, GPS, morphotectonics, fieldwork, and brittle deformation analysis. Extension appears to be the dominant process in the present-day tectonic activity in the Western Alps, affecting its internal areas all along the arc. Shortening, in contrast, is limited to small areas located along at the outer borders of the chain. Strike-slip is observed throughout the Alpine realm and in the foreland. The stress-orientation pattern is radial for r3 in the inner, extensional zones, and for r1 in the outer, transcurrent/tranpressional ones. Extensional areas can be correlated with the parts of the belt with the thickest crust. Quantification of seismic strain in tectonically homogeneous areas shows that only 10-20% of the geodesy-documented deformation can be explained by the Alpine seismicity. We propose that, Alpine active tectonics are ruled by isostasy/buoyancy forces rather than the ongoing shortening along the Alpine Europe/Adria collision zone. This interpretation is corroborated by numerical modeling. The Neogene extensional structures in the Alps formed under increasingly brittle conditions. A synthesis of paleostress tensors for the internal parts of the West-Alpine Arc documents major orogen-parallel extension with a continuous change in r3 directions from ENE-WSW in the Simplon area, to N-S in the Vanoise area and to NNW-SSE in the Briançon area. Minor orogen-perpendicular extension increases from N to S. This second signal correlates with the present-day geodynamics as revealed by focal-plane mechanisms analysis. The orogen-parallel extension could be related to the opening of the Ligurian Sea during the Early-Middle Miocene and to compression/ rotation of the Adriatic indenter inducing lateral extrusion.

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“…2003). A focal mechanism proposed by Ahorner et al. (1972) suggested an NNE–SSW trending, steeply dipping, strike–slip fault.…”

Section: Seep Description and Geologic Settingmentioning

confidence: 99%

“…On 14 March 1964, after a series of numerous seismic events that occurred over several months, an earthquake with a magnitude of Mw = 5.7 and Io = VII occurred approximately 5 km east of Lake Sarnen with a hypocenter at a depth of 5-7 km . A focal mechanism proposed by Ahorner et al (1972) suggested an NNE-SSW trending, steeply dipping, strike-slip fault. However, a review of the data revealed no clear solution for the focal mechanism (Deichmann et al 2000).…”

Section: Seep Description and Geologic Settingmentioning

confidence: 99%

Origin and flux of a gas seep in the Northern Alps (Giswil, Switzerland)

Etiope¹,

Zwahlen²,

Anselmetti³

et al. 2010

Geofluids

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Natural gas seeps in the Alpine region are poorly investigated. However, they can provide useful information regarding the hydrocarbon potential of sedimentary Alpine units and related geofluid migration, typically controlled by pressurized gas accumulations and tectonics. A gas seep located near Giswil, in the Swiss Northern Alps, was investigated, for the first time, for molecular and isotopic gas composition, methane flux to the atmosphere, and gas flux variations over time. The analyses indicated that the gas was thermogenic (CH 4 > 96%; d 13 C 1 : )35.5& to )40.2&) and showed evidence of subsurface petroleum biodegradation ( 13 C-enriched CO 2 , and very low C 3+ concentrations). The source rock in the region is marine Type II kerogen, which is likely the same as that providing thermogenic gas in the nearby Wilen shallow well, close to Lake Sarnen. However, the lack of d 13 C CO2 and d 13 C 3 data for that well prevented us from determining whether the Wilen and Giswil seeps are fed by the same reservoir and seepage system. Gas fluxes from the Giswil seep, measured using a closedchamber system, were significant and mainly from two major vents. However, a substantial gas exhalation from the soil occurs diffusely in an area of at least 115 m 2 , leading to a total CH 4 output conservatively estimated to be at least 16 tonnes per year. Gas flux variations, monitored over a 1-month period by a special tent and flowmeter, showed not only daily meteorological oscillations, but also an intrinsic 'pulsation' with periods of enhanced flux that lasted 2-6 h each, occurring every few days. The pulses are likely related to episodes of gas pressure build-up and discharge along the seepage system. However, to date, no relationship to seismicity in the active Sarnen strike-slip fault system has been established.

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Seismotektonische Traverse von der Nordsee bis zum Apennin

Cited by 44 publications

References 24 publications

Crustal structure and active tectonics in the Eastern Alps

Crustal structure and active tectonics in the Eastern Alps

Extensional neotectonics around the bend of the Western/Central Alps: an overview

Origin and flux of a gas seep in the Northern Alps (Giswil, Switzerland)

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