scholarly journals Implications from palaeoseismological investigations at the Markgrafneusiedl Fault (Vienna Basin, Austria) for seismic hazard assessment

2018 ◽  
Vol 18 (2) ◽  
pp. 531-553 ◽  
Author(s):  
Esther Hintersberger ◽  
Kurt Decker ◽  
Johanna Lomax ◽  
Christopher Lüthgens
Keyword(s):  
Seismic Hazard ◽  
Hazard Assessment ◽  
Seismic Hazard Assessment ◽  
Slip Model ◽  
Vienna Basin ◽  
Slip Rates ◽  
Strong Earthquakes ◽  
Earthquake Frequency ◽  
Splay Faults ◽  
Magnitude Estimates

Abstract. Intraplate regions characterized by low rates of seismicity are challenging for seismic hazard assessment, mainly for two reasons. Firstly, evaluation of historic earthquake catalogues may not reveal all active faults that contribute to regional seismic hazard. Secondly, slip rate determination is limited by sparse geomorphic preservation of slowly moving faults. In the Vienna Basin (Austria), moderate historical seismicity (Imax,obs/Mmax,obs=8/5.2) concentrates along the left-lateral strike-slip Vienna Basin Transfer Fault (VBTF). In contrast, several normal faults branching out from the VBTF show neither historical nor instrumental earthquake records, although geomorphological data indicate Quaternary displacement along those faults. Here, located about 15 km outside of Vienna, the Austrian capital, we present a palaeoseismological dataset of three trenches that cross one of these splay faults, the Markgrafneusiedl Fault (MF), in order to evaluate its seismic potential. Comparing the observations of the different trenches, we found evidence for five to six surface-breaking earthquakes during the last 120 kyr, with the youngest event occurring at around 14 ka. The derived surface displacements lead to magnitude estimates ranging between 6.2±0.5 and 6.8±0.4. Data can be interpreted by two possible slip models, with slip model 1 showing more regular recurrence intervals of about 20–25 kyr between the earthquakes with M≥6.5 and slip model 2 indicating that such earthquakes cluster in two time intervals in the last 120 kyr. Direct correlation between trenches favours slip model 2 as the more plausible option. Trench observations also show that structural and sedimentological records of strong earthquakes with small surface offset have only low preservation potential. Therefore, the earthquake frequency for magnitudes between 6 and 6.5 cannot be constrained by the trenching records. Vertical slip rates of 0.02–0.05 mm a−1 derived from the trenches compare well to geomorphically derived slip rates of 0.02–0.09 mm a−1. Magnitude estimates from fault dimensions suggest that the largest earthquakes observed in the trenches activated the entire fault surface of the MF including the basal detachment that links the normal fault with the VBTF. The most important implications of these palaeoseismological results for seismic hazard assessment are as follows. (1) The MF is an active seismic source, capable of rupturing the surface despite the lack of historical earthquakes. (2) The MF is kinematically and geologically equivalent to a number of other splay faults of the VBTF. It is reasonable to assume that these faults are potential sources of large earthquakes as well. The frequency of strong earthquakes near Vienna is therefore expected to be significantly higher than the earthquake frequency reconstructed for the MF alone. (3) Although rare events, the potential for earthquake magnitudes equal or greater than M=7.0 in the Vienna Basin should be considered in seismic hazard studies.

scholarly journals Implications from palaeoseismological investigations at the Markgrafneusiedl Fault (Vienna Basin, Austria) for seismic hazard assessment

2017 ◽  
Author(s):  
Esther Hintersberger ◽  
Kurt Decker ◽  
Johanna Lomax ◽  
Christopher Lüthgens
Keyword(s):  
Seismic Hazard ◽  
Hazard Assessment ◽  
Active Faults ◽  
Seismic Hazard Assessment ◽  
Vienna Basin ◽  
Slip Rates ◽  
Small Surface ◽  
Strong Earthquakes ◽  
Splay Faults ◽  
Magnitude Estimates

Abstract. Including faults into seismic hazard assessment depends strongly on their level of seismic activity. Intraplate regions are characterized by low seismicity, so that the evaluation of existing earthquake catalogues does not necessarily reveal all active faults that contribute to seismic hazard. In the Vienna Basin (Austria), moderate historical seismicity (Imax/Mmax = 8/5.2) concentrates along the left-lateral strike-slip Vienna Basin Transfer Fault (VBTF). In contrast, several normal faults branching out of the VBTF show neither historical nor instrumental earthquake records, although geomorphological data indicate Quaternary displacement along those faults. Here, we present a palaeoseismological dataset of three trenches crossing one of these splay faults, the Markgrafneusiedl Fault (MF), in order to evaluate the seismic potential of the fault. Comparing the observations of the different trenches, we found evidence for 5–6 major surface-breaking earthquakes during the last 120 ka, with the youngest event occurring at around ~ 14 ka before present. The inferred surface displacements lead to magnitude estimates ranging between M = 6.2 ± 0.3 and M = 6.8 ± 0.1. Data can be interpreted by two possible event lines, with event line 1 showing more regular recurrence intervals of about 20–25 ka between the earthquakes with M ≥ 6.5, and event line 2 indicating that such earthquakes cluster in two time intervals in the last 120 ka. Event line 2 appears more plausible. Trench observations also show that structural and sedimentological records of strong earthquakes with small surface offset have only low conservation potential. Vertical slip rates of 0.03–0.04 mm/a derived from the trenches compare well to geomorphically derived slip rates of 0.015–0.085 mm/a. Magnitude estimates from fault dimensions suggest that the largest earthquakes observed in the trenches activated the entire fault surface of the MF including the basal detachment that links the normal fault with the VBTF. The most important implications of these paleoseismological results for seismic hazard assessment are that: (1) The MF needs to be considered as a seismic source irrespective of the fact that it did not release historical earthquakes. (2) The maximum credible earthquakes in the Vienna Basin should be considered to be about M = 7.0. (3) The MF is kinematically and geologically equivalent to a number of other splay faults of the VBTF. It must be assumed that these faults are potential sources of large earthquakes as well. The frequency of strong earthquakes near Vienna is therefore expected to be significantly higher than the earthquake frequency reconstructed for the MF.

scholarly journals Bayesian earthquake dating and seismic hazard assessment using chlorine-36 measurements (BED v1)

2018 ◽  
Vol 11 (11) ◽  
pp. 4383-4397 ◽  
Author(s):  
Joakim Beck ◽  
Sören Wolfers ◽  
Gerald P. Roberts
Keyword(s):  
Inverse Problem ◽  
Seismic Hazard ◽  
Hazard Assessment ◽  
Ad Hoc ◽  
Seismic Hazard Assessment ◽  
Fault Scarp ◽  
Physical Models ◽  
Monte Carlo Algorithm ◽  
Slip Rates ◽  
Chlorine 36

Abstract. Over the past 20 years, analyzing the abundance of the isotope chlorine-36 (36Cl) has emerged as a popular tool for geologic dating. In particular, it has been observed that 36Cl measurements along a fault plane can be used to study the timings of past ground displacements during earthquakes, which in turn can be used to improve existing seismic hazard assessment. This approach requires accurate simulations of 36Cl accumulation for a set of fault-scarp rock samples, which are progressively exhumed during earthquakes, in order to infer displacement histories from 36Cl measurements. While the physical models underlying such simulations have continuously been improved, the inverse problem of recovering displacement histories from 36Cl measurements is still mostly solved on an ad hoc basis. The current work resolves this situation by providing a MATLAB implementation of a fast, automatic, and flexible Bayesian Markov-chain Monte Carlo algorithm for the inverse problem, and provides a validation of the 36Cl approach to inference of earthquakes from the demise of the Last Glacial Maximum until present. To demonstrate its performance, we apply our algorithm to a synthetic case to verify identifiability, and to the Fiamignano and Frattura faults in the Italian Apennines in order to infer their earthquake displacement histories and to provide seismic hazard assessments. The results suggest high variability in slip rates for both faults, and large displacements on the Fiamignano fault at times when the Colosseum and other ancient buildings in Rome were damaged.

scholarly journals Bayesian earthquake dating and seismic hazard assessment using chlorine-36 measurements (BED v1)

2018 ◽  
Author(s):  
Joakim Beck ◽  
Sören Wolfers ◽  
Gerald P. Roberts
Keyword(s):  
Inverse Problem ◽  
Seismic Hazard ◽  
Hazard Assessment ◽  
Ad Hoc ◽  
Seismic Hazard Assessment ◽  
Fault Scarp ◽  
Physical Models ◽  
Monte Carlo Algorithm ◽  
Slip Rates ◽  
Chlorine 36

Abstract. Over the past twenty years, analyzing the abundance of the isotope chlorine-36 (36Cl) has emerged as a popular tool for geologic dating. In particular, it has been observed that 36Cl measurements along a fault plane can be used to study the timings of past ground displacements during earthquakes, which in turn can be used to improve existing seismic hazard assessment. This approach requires accurate simulations of 36Cl accumulation for a set of fault-scarp rock samples, which are progressively exhumed during earthquakes, in order to infer displacement histories from 36Cl measurements. While the physical models underlying such simulations have continuously been improved, the inverse problem of recovering displacement histories from 36Cl measurements is still mostly solved on an ad-hoc basis. The current work resolves this situation by providing a MATLAB implementation of a fast, automatic, and flexible Bayesian Markov-chain Monte Carlo algorithm for the inverse problem, and provides a validation of the 36Cl approach to inference of earthquakes from the demise of the Last Glacial Maximum until present. To demonstrate its performance, we apply our algorithm to a synthetic case to verify identifiability, and to the Fiamignano and Frattura faults in the Italian Apennines in order to infer their earthquake displacement histories and to provide seismic hazard assessments. The results suggest high variability in slip rates for both faults, and large displacements on the Fiamignano fault at times when the Colosseum and other ancient buildings in Rome were damaged.

scholarly journals Crustal faults in the Chilean Andes: geological constraints and seismic potential

2018 ◽  
Vol 46 (1) ◽  
pp. 32 ◽  
Author(s):  
Isabel Santibáñez ◽  
José Cembrano ◽  
Tiaren García-Pérez ◽  
Carlos Costa ◽  
Gonzalo Yáñez ◽  
...  
Keyword(s):  
Seismic Hazard ◽  
Hazard Assessment ◽  
Seismic Hazard Assessment ◽  
Fault Reactivation ◽  
South American ◽  
Slip Rates ◽  
Seismic Potential ◽  
Recurrence Times ◽  
Wide Range ◽  
Chilean Andes

The Chilean Andes, as a characteristic tectonic and geomorphological region, is a perfect location to unravel the geologic nature of seismic hazards. The Chilean segment of the Nazca-South American subduction zone has experienced mega-earthquakes with Moment Magnitudes (Mw) >8.5 (e.g., Mw 9.5 Valdivia, 1960; Mw 8.8 Maule, 2010) and many large earthquakes with Mw >7.5, both with recurrence times of tens to hundreds of years. By contrast, crustal faults within the overriding South American plate commonly have longer recurrence times (thousands of years) and are known to produce earthquakes with maximum Mw of 7.0 to 7.5. Subduction-type earthquakes are considered the principal seismic hazard in Chile, with the potential to cause significant damage to its population and economy. However crustal (non-subduction) earthquakes can also cause great destruction at a local scale, because of their shallower hypocentral depth. Nevertheless, the nature, timing and slip rates of crustal seismic sources in the Chilean Andes remain poorly constrained. This work aims to address the seismic potential of the crustal faults in Chile, contributing to the estimation of key fault parameters for the seismic hazard assessment. We have examined the main parameters involved in the magnitude of an earthquake, including length, width and mean displacement of some case studies crustal faults and their morphotectonic settings, exposing the parametrical similarities in longitudinal domains (N-S stripes) and disparity from W to E, across latitudinal domains. The maximum hypocentral depths for crustal earthquakes vary across margin parallel tectonic domains aligned parallel, from 25-30 km in the outer forearc to 8-12 km in the volcanic arc, thus allowing for a first-order approach for seismic potential assessment. Current structural, paleoseismological and geodetic data, although sparse and limited, suggest that slip rates of Chilean crustal faults range from 0.2 mm/yr (in the forearc region) to up to 7.0 mm/yr (in the intra-arc region). The different tectonic modes for crustal fault reactivation and their wide range of slip rates complicates the estimation of seismic hazard. A rigorous seismic hazard assessment must therefore consider the different tectonic settings, timing and slip rates of Andean crustal faults. Understanding the nature of these faults will allow a better evaluation of the associated seismic hazard, and better constraints to be placed on their relationship with the subduction seismic cycle.

scholarly journals Geodetic fault slip rates on active faults in the Baza sub-Basin (SE Spain): Insights for seismic hazard assessment

2021 ◽  
Vol 144 ◽  
pp. 101815
Author(s):  
P. Alfaro ◽  
A. Sánchez-Alzola ◽  
I. Martin-Rojas ◽  
F.J. García-Tortosa ◽  
J. Galindo-Zaldívar ◽  
...  
Keyword(s):  
Seismic Hazard ◽  
Hazard Assessment ◽  
Active Faults ◽  
Seismic Hazard Assessment ◽  
Fault Slip ◽  
Se Spain ◽  
Slip Rates ◽  
Fault Slip Rates

scholarly journals Detecting premonitory seismicity patterns based on critical point dynamics

2001 ◽  
Vol 1 (1/2) ◽  
pp. 93-98 ◽  
Author(s):  
G. Zöller ◽  
S. Hainzl
Keyword(s):  
Seismic Hazard ◽  
Critical Point ◽  
Spatial Correlation ◽  
Spatial Patterns ◽  
Hazard Assessment ◽  
Seismic Hazard Assessment ◽  
Seismicity Patterns ◽  
Strong Earthquakes ◽  
Loma Prieta Earthquake ◽  
Spatial Correlation Length

Abstract. We test the hypothesis that critical point dynamics precedes strong earthquakes in a region surrounding the future hypocenter. Therefore, we search systematically for regions obeying critical point dynamics in terms of a growing spatial correlation length (GCL). The question of whether or not these spatial patterns are correlated with future seismicity is crucial for the problem of predictability. The analysis is conducted for earthquakes with M > 6.5 in California. As a result, we observe that GCL patterns are correlated with the distribution of future seismicity. In particular, there are clear correlations in some cases, e.g. the 1989 Loma Prieta earthquake and the 1999 Hector Mine earthquake. We claim that the critical point concept can improve the seismic hazard assessment.

System-analytical method of strong earthquake-prone areas recognition

2021 ◽  
Author(s):  
Boris Dzeboev ◽  
Alexei Gvishiani ◽  
Boris Dzeranov
Keyword(s):  
Seismic Hazard ◽  
Hazard Assessment ◽  
Analytical Method ◽  
Strong Earthquake ◽  
Subduction Zones ◽  
Seismic Hazard Assessment ◽  
Hazard Identification ◽  
Strong Earthquakes ◽  
Weak Earthquakes ◽  
High Seismicity

<p>Proper seismic hazard assessment is the most important scientific problem of seismology, and geophysics in general. With the development of the world economy, the importance of the problem grows and acquires global significance.</p><p>Strong earthquakes (M ≥ M<sub>0</sub>, M<sub>0</sub> is the magnitude threshold starting from which earthquakes in the studied region are considered strong), as a rule, do not occur over the entire territory of the seismic region. Accordingly, the recognition of areas prone to future strong earthquakes is an urgent fundamental direction in research on the assessment of seismic hazard. Identification of potentially high seismicity zones in seismically active regions is important from both theoretical, and practical points of view. The currently available methods for recognition of high seismicity zones do not allow repeatedly correcting their results over time due to the invariability of the used set of recognition objects. In this work, a new system-analytical approach FCAZ (Formalized Clustering And Zoning) to the problem has been created. It uses the epicenters of rather weak earthquakes (M ≥ M<sub>R</sub>, M<sub>R</sub> is a certain magnitude threshold of weak earthquakes) as objects of recognition. This makes it possible to develop the recognition result of zones with increased seismic hazard after the appearance of new earthquake epicenters. The latter makes FCAZ a method of systems analysis.</p><p>The system-analytical method for analyzing geophysical data developed by the authors has led to the successful recognition of areas prone to the strongest, strong, and most significant earthquakes on the continents of North, and South America, Eurasia, and in the subduction zones of the Pacific Rim. At the same time, in particular, for the classical approach of strong earthquake-prone areas recognition EPA (Earthquake-Prone Areas), a new paradigm for recognition of high seismicity disjunctive nodes, and lineament intersections with training by one “reliable” class was created in the work.</p><p>In the regions studied in this work, FCAZ zones occupy a relatively small area compared to the field of general seismicity – 30% – 40% of the area of all seismicity, and 50% – 65% of the area where earthquakes with M ≥ M<sub>R</sub> occur. This illustrates the spatial nontriviality of the FCAZ results obtained in this work. The results of the work also show that weak seismicity can actually “manifest” the properties of geophysical fields, which in the classical EPA approach are used directly as characteristics of recognition objects (disjunctive nodes or intersections of the axes of morphostructural lineaments).</p><p>The reported study was funded by RFBR, project number 20-35-70054 «Systems approach to recognition algorithms for seismic hazard assessment».</p>

scholarly journals Seismic hazard assessment of the earth dams under strong earthquakes

2016 ◽  
pp. 18-21
Author(s):  
Sergey Petrovich Serebrennikov ◽  
◽  
Vasiliy Ionovich Dzhurik ◽  
Aleksandr Yurievich Eskin ◽  
Evgeniy Vladimovich Bryzhak ◽  
...  
Keyword(s):  
Seismic Hazard ◽  
Hazard Assessment ◽  
Seismic Hazard Assessment ◽  
Earth Dams ◽  
Strong Earthquakes ◽  
The Earth

scholarly journals ARCHEOSEISMOLOGICAL STUDY AT ANCIENT TAURIC CHERSONESOS (SEVASTOPOL, CRIMEA)

2016 ◽  
Author(s):  
А.В. Мараханов ◽  
А.С. Ларьков ◽  
А.Н. Овсюченко ◽  
А.М. Корженков ◽  
В.В. Хапаев
Keyword(s):  
Seismic Hazard ◽  
Hazard Assessment ◽  
Seismic Hazard Assessment ◽  
Military Operations ◽  
Strong Earthquakes ◽  
Archaeological Data ◽  
The Past ◽  
Unique Possibility

Руины хорошо изученного древнего города Херсонес Таврический дают уникальную возможность для восстановления сейсмической истории Южного Крыма за последние 2,5 тыс. лет. Специфические деформации в стенах Херсонеса Таврического однозначно свидетельствуют о неоднократных сильных землетрясениях, происходивших в далёком прошлом. В результате проведённых исследований удалось выявить следы, по крайней мере, двух или трех сильных землетрясений. Массовые разрушения в городе и его округе, не связанные с военными действиями, датируются: III в. н.э., V или VI в. н.э. и рубежом X−XI вв. н.э. Совместное использование исторических и археологических свидетельств открывает принципиально новые возможности для оценки сейсмической опасности Ruins of well studied ancient Tauric Chersonesos give unique possibility for restoration of Southern Crimea seismic history for last 2,5 thousand years. Specific deformations within the walls of Chersonesos clearly testify to the numerous strong earthquakes occurring far back in the past. As a result of the studies it was possible to reveal traces, at least, two or three strong earthquakes. Mass destructions in a city and its district, not connected with military operations, are dated: III century AD, V or VI century AD and a boundary X−XI centuries AD. Sharing of historical and archaeological data opens essentially new possibilities for seismic hazard assessment

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