Central Europe
Total Page:16
File Type:pdf, Size:1020Kb
Neotectonics of stable continental interiors - active faults in Central Europe KLAUS REICHERTER Neotectonics & Natural Hazards, RWTH Aachen University, Germany. email: [email protected] Neotectonics of stable continental interiors - active faults in Central Europe • Neotectonics • Stable Continental Interiors • Central Europe • active faults Neotectonics - Definitions OBRUCHEV (1948): “... the study of the young and recent crustal movements taking Place at the end of the Tertiary and the first half of the Quaternary” “... das Studium von jungen und rezenten Krustenbewegungen ab dem Ende des Tertiärs und der ersten Hälfte des Quartärs” Neotectonics - Definitions MÖRNER (1990, died 2020): “Neotectonics starts at different times in different places, depending on the tectonic regime.” “Neotektonik beginnt zu verschiedenen Zeiten an verschiedenen Orten, abhängig vom tektonischen Regime.” MUIR-WOOD & MALLARD (1992): “Neotectonic structures develop in the current tectonic regime.” „Neotektonische Strukturen entwickeln sich in gegenwärtigen tektonischen Regime.” Active tectonics - Definitions WALLACE (1986) (Active Tectonics): “... is defined as tectonic movements that are expected to occur within a future time span of concern to society.” „ wird definiert als tektonische Bewegungen, die sich in Zukunft ereignen können, und die Gesellschaft betreffen.“ "Active Faults“ - „aktive Störungen“ ... Last 10.000 years (Califor.) Flächen bewegten sich in den letzten 10.000 Jahren ... Last 35.000 years in tectonically active areas (35.000 Jahre) ... Last 150.000 years for all other areas (150.000 Jahre) ...or 2x time in the last 500 ky (Flächen bewegten sich zwei Mal in den letzten 500.000 Jahren (Definition of the US Nuclear Agency/ der US Strahlenbehörde) Neo-/ active tectonics - Definitions IAEA: capable faults concept includes: v reactivation and inheritance v segmentation v paleoseismicity/-ology v diffuse seismicity � 100 ka cycles (or 2 x in 500 ka) Stable continental interiors Seismicity from CalTech, 2000-2008 Stable Continental Interiors – Normal faults Yeats et al. 1997 Stable Continental Interiors – Normal faults Yeats et al. 1997 examples: East African Rift, Taupo, Basin and Range and Baikal Rifts are mainly volcanic Stable Continental Interiors – Strike-slip faults Yeats et al. 1997 Stable Continental Interiors – Strike-slip faults Yeats et al. 1997 examples: Atacama/Liquine Ofqui F., Sagaing F., Altyn Tagh F., Talasso Ferghana. F. BUT also New Madrid area (1811/2) Stable Continental Interiors – Thrust faults Yeats et al. 1997 Stable Continental Interiors – Thrust faults Yeats et al. 1997 examples: Australia, Finland, Canada Stable Continental Interiors Glacial Isostatic Adjustment (GIA): Glacial rebound • In Regions of former glaciation: • Scandinavia, Alps • Canada and NE USA • Regions with 2 - 3 km thick ice sheets • Melting induced 500 – 1000 m uplift • Intensive directly after melting ca. ~15.000 years ago • Uplift rate to 50 cm/year (10(0) x tectonic rate) • Exponential decay to ~ 1 cm / year • until today ~ 1 cm / year • Decay of uplift leads to decay of earthquake activity (long- term hazard assessment) from: http://earthscience-longoria.blogspot.com • fore bulge in front of thick ice sheets Stable Continental Interiors Glacial Isostatic Adjustment (GIA): Glacial rebound https://www.maanmittauslaitos.fi Gregersen and Voss, 2009 Stable Continental Interiors So what is different? recurrence periods (activity) segmentation repeated reactivation in cycle (weakening crust and fault zones) clustering? re-adjustment to regional stresses This means: classical Californian paleoseismic approaches Kukkonen et al. 2010 do not help! Active faults - paleoseismicity Gutenberg-Richter law (-Relation): log10N=a-bM (a, b = constants) a) characteristic b) fault strength dependent c) stress drop dependent McCalpin 2009 Active faults - paleoseismicity After the San Francisco 1906 earthquake H.F. Reid develops seismic cycle model eq for GIA Faults: eq a) characteristic b) fault strength dependent c) stress drop dependent time static dynamic recurrence/magnitude identical recurrence?magnitude? intensity? Active faults - paleoseismicity Ross Stein explaining � friction matters...... Active faults - paleoseismicity fault length matters � but segment (boundaries)..... again the California model.... Active faults - paleoseismicity fault length matters � but segment (boundaries)..... Basili R., et al., (2013). The European Database of Seismogenic Faults (EDSF) compiled in the framework of the Project SHARE. http://diss.rm.ingv.it/share-edsf/, doi:10.6092/INGV.IT-SHARE-EDSF. Central Europe Active faults - paleoseismicity Frisch & Meschede, 2005 Central Europe Active faults - paleoseismicity ca. 100 Mio. € damage EQ Roermond, 13.4.1992, local M 5,9 (5.4) Central Europe Topography LiDAR Central Europe Grützner et al. 2016 Alegra 2019 Scriptum 2008 Central Europe Central Europe Central Europe Central Europe Geology Central Europe 4 events postglacial plus ERT and GPR data Sandgewand Fault, Zeelink pipeline trench Central Europe Seismic survey together with Hans Balder Havenith/ULiege Central Europe Central Europe Ochtendung Fault Eifel volcanics: the most active fault in Germany bringing seis- city data to surface from Bernd Schmidt LGBRP Central Europe Eifel volcanics: bringing seis- city data to surface Central Europe Upper Rhine Graben • evidence for 35 km left-lateral displace- ment since Miocene • Rift shoulder exhumation • Seismicity distributed • segemented marginal faults Central Europe Central Europe Karlsruhe Ettlingen Durlach Alb valley Rhine river Upper Rhine Rüppurr Wolfartsweier Graben Ettlingenweier RGBF terrace b BV a TF Ettlingen riser (erosional Alb TF Ettlingenweier scarp) Ettlingen Oberweier Oberweier BV TF BV fault scarp Sulzbach BV TF E09 Malsch BV E06 BV Sulzbach TF Waldprechtsweier BV E02 E01 E03 Niederweier BV E04 TF TF km km m 0 2 4 8 0 0.5 1 2 0 15 30 60 A Geology B Morphology C Trench site and geophysics Central Europe Central Europe T1 S-wall, Oberweier Colluvial wedge is faulted à two events, minimum Central Europe T1 S-wall, Oberweier Dating: asteriks – 14C; yellow x OSL Central Europe Central Europe Conclusion: One shot faults and clustered eqs are a real challenge! Many clusters around late Glacial and (GIA).... Seismic (short term) observation may give a hint Fault tips? We need new approaches and thinking for intraplate seismicity, as „traditional“ paleoseismicity does not work. Central Europe Teilgebiete gemäß §13 Standortauswahlgesetz.