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We focus on Swiss earthquakes in antiquity and the early medieval period before A.D. 1000. We have information on less than
half a dozen earthquakes within this era, since written records for the first half of the first millennium A.D. are minimal,
and there is little hope of finding more written evidence for earthquakes. Furthermore, interpreting...
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Citations
... As the historical period varies between countries and cultures, we consider the definition used in the original publications (e.g. In Switzerland, historical documents describe natural hazards already in the 6th century (Gisler et al., 2007) while in New Zealand the first written records are dated around 1840 CE (Clark et al., 2015)). Historical events related to human activity, e.g. ...
In freshwater systems (rivers and lakes), historical and recent tsunamis have been documented and their traces have been found in the geological record, but studies of paleotsunamis (prehistorical tsunamis) in such environments are still underrepresented. This contribution reviews paleotsunami studies with a focus on the post − 2011 period and uses historical events to highlight some areas of research that have received little attention. In the past decade, the number of paleotsunami studies has increased and this includes those carried out over freshwater settings. However, studies of lacustrine paleotsunamis compared to studies on marine paleotsunamis are still rare and those for rivers are to our knowledge non-existent. Similarly, studies of historical tsunamis generated by meteorological disturbances have been carried out but there have been none for their paleotsunami counterpart. Thus, within this review, to cover all different aspects of tsunami generation processes in freshwater systems, we have used several historical examples, although there is a notable focus on lacustrine paleotsunamis. This review shows that future studies of freshwater paleotsunamis are necessary in order to better understand their causes, frequencies and hazard potential.
... In this study, we use the term 'prehistoric' as the time before 1000 AD that marks in Switzerland the beginning of the available documentation of natural phenomena (Gisler et al. 2007). Before, only a few documents exist that are mentioning earthquakes back to 250 AD Gisler et al. 2007). ...
... In this study, we use the term 'prehistoric' as the time before 1000 AD that marks in Switzerland the beginning of the available documentation of natural phenomena (Gisler et al. 2007). Before, only a few documents exist that are mentioning earthquakes back to 250 AD Gisler et al. 2007). ...
Paleoseismological evidence is indispensable for the identification of large prehistoric earthquakes and the extension of the temporal coverage of historical and instrumental earthquake catalogues. In the geological record, diverse traces of past earthquakes are found. This study presents a database of potential primary and secondary evidence for seismic activity in the past 20,000 years in Switzerland. The database includes data from sedimentological, archaeological, speleological and geomorphological research. This unique dataset allows identifying periods during which the geologic record reveals enhanced occurrence of evidence that are further discussed as potentially earthquake-triggered. For the most recent 700 years, an increased occurrence of evidence features was found. This clustering is an effect of the historical earthquakes. Furthermore, periods with enhanced occurrence are identified at six phases during the past 20,000 years. Even though dating uncertainties for the geological record are large (e.g. 14C calibration range) and an unequivocal attribution of earthquakes as trigger mechanism for secondary evidence is not possible, the database reflects the natural-hazard potential of a region and represents valuable information for seismic hazard assessment. Furthermore, despite the uncertainty regarding the definition of the trigger mechanism, we propose that the database can be used to validate and improve earthquake-hazard models.
... These large uncertainties are mainly due to the estimation of the SED ages by down-core extrapolation of sedimentation rates determined in the upper sediment via 137 Cs and 210 Pb measurements and/or with 14 C ages and historical events. Age control in Lake Thun is based on 137 Cs dating, the horizon of the Kander River deviation (1714 AD) and a rockfall in 598/599 AD recorded in historic sources (Gisler et al., 2007;Wirth et al., 2011). The SEDs were dated via extrapolation of the sedimentation rate between 1714 and 598/99 to larger sediment depths. ...
In regions with moderate seismicity and large intervals between strong earthquakes, paleoseismological archives that exceed the historical and instrumental timescale are needed to establish reliable estimates of earthquake recurrence for long return periods. In several regions, lake sediments have shown to be suitable for paleoseismological studies by causally linking characteristic sedimentological features to historic earthquakes. Studies on single lakes, however, do neither allow determining the paleoepicentre nor the paleomagnitude for the potential paleoearthquakes. Here we compile, using shaking-induced mass movements and micro deformations (summarized as Sedimentary Event Deposits SEDs), the sedimentary paleoseismic record of 11 lakes from Switzerland over the last 10,000 years. The large dating uncertainty attributed to such deposits (up to 250 years) does not allow us to conclusively test for one large earthquake hypothesis when comparing the different lake records and therefore represents one of the major limitations of this approach. Instead, using a new approach of exploring the normalized frequency of occurrence averaged over a larger area, the compiled dataset reveals striking periods of enhanced occurrence of SEDs in the studied lakes during several phases of the past 10,000 years, centered at 9700, 6500 and during the last 4000 cal yr BP. Moreover, we use a calibrated intensity attenuation relation in order to model scenarios of possible epicentral areas and ranges of magnitudes of paleoearthquakes. We differentiate two cases: (i) a ‘single-earthquake’ scenario if SEDs occur simultaneously in various studied lakes, or (ii) a ‘multi-earthquake’ scenario if SEDs in the studied lakes cluster within a time interval. The modelled scenarios allow us to propose maximally possible magnitudes of large paleoearthquakes, constituting an important input for seismic hazard assessment in the Swiss Alps.
... The strongest documented earthquake (MW 6.6, EMS-98 epicentral intensity IX) to have occurred in central Europe was located in the region of Basel (at the border among Switzerland, France and Germany) in 1356, with significant destruction to the city (Fäh et al., 2009). Based on well documented historical seismicity in Switzerland (Gisler et al., 2003, Schwarz-Zanetti et al., 2003, Gisler et al., 2004a, Gisler et al., 2004b, Gisler et al., 2004c, Schwarz-Zanetti et al., 2004, Fritsche et al., 2006, Gisler et al., 2007, e.g., Fäh et al., 2009, Fritsche et al., 2012), seismic hazard is clearly an important issue to address. The topic has seen significant focus and progress in the last 15 years. ...
We present a strategy for the region‐specific assessment, adjustment, and weighting of ground‐motion prediction models, with application to the 2015 Swiss national seismic‐hazard maps. The models are provided within a logic‐tree framework adopted for the probabilistic seismic‐hazard analysis (PSHA). Through this framework, we consider both aleatory and epistemic uncertainties in ground‐motion prediction in Switzerland, a region of low‐to‐moderate seismicity and consequently data poor in terms of strong‐motion records. We use both empirical models developed using global strong‐motion data and stochastic simulation models calibrated to local seismicity, characteristic wave‐propagation effects, and site conditions. The empirical models were adjusted to account for (a) the selected hazard reference rock velocity model (using VS‐κ0 adjustments) and (b) the median instrumental ground‐motion data at low magnitudes. The use of a carefully calibrated simulation model and VS‐κ0 adjusted empirical ground‐motion prediction equations allowed us to precisely define the reference‐rock profile, upon which subsequent analyses, such as microzonation and site‐specific hazard, can be applied without uncertainty related to the reference condition. We implemented partially nonergodic aleatory uncertainties in ground‐motion prediction through the single‐station sigma approach. This strategy, complemented with the known reference rock condition, leads to significant reductions in the contribution of uncertainty in ground‐motion characterization to PSHA in Switzerland. However, the application of the methodological framework outlined herein extends to any region, particularly those of low‐to‐moderate seismicity.
... The strongest documented earthquake (MW 6.6, EMS-98 epicentral intensity IX) to have occurred in central Europe was located in the region of Basel (at the border among Switzerland, France and Germany) in 1356, with significant destruction to the city (Fäh et al., 2009). Based on well documented historical seismicity in Switzerland (Gisler et al., 2003, Schwarz-Zanetti et al., 2003, Gisler et al., 2004a, Gisler et al., 2004b, Gisler et al., 2004c, Schwarz-Zanetti et al., 2004, Fritsche et al., 2006, Gisler et al., 2007, e.g., Fäh et al., 2009, Fritsche et al., 2012), seismic hazard is clearly an important issue to address. The topic has seen significant focus and progress in the last 15 years. ...
We present a strategy for the region‐specific assessment, adjustment, and weighting of ground‐motion prediction models, with application to the 2015 Swiss national seismic‐hazard maps. The models are provided within a logic‐tree framework adopted for the probabilistic seismic‐hazard analysis (PSHA). Through this framework, we consider both aleatory and epistemic uncertainties in ground‐motion prediction in Switzerland, a region of low‐to‐moderate seismicity and consequently data poor in terms of strong‐motion records. We use both empirical models developed using global strong‐motion data and stochastic simulation models calibrated to local seismicity, characteristic wave‐propagation effects, and site conditions. The empirical models were adjusted to account for (a) the selected hazard reference rock velocity model (using VS‐κ0 adjustments) and (b) the median instrumental ground‐motion data at low magnitudes. The use of a carefully calibrated simulation model and VS‐κ0 adjusted empirical ground‐motion prediction equations allowed us to precisely define the reference‐rock profile, upon which subsequent analyses, such as microzonation and site‐specific hazard, can be applied without uncertainty related to the reference condition. We implemented partially nonergodic aleatory uncertainties in ground‐motion prediction through the single‐station sigma approach. This strategy, complemented with the known reference rock condition, leads to significant reductions in the contribution of uncertainty in ground‐motion characterization to PSHA in Switzerland. However, the application of the methodological framework outlined herein extends to any region, particularly those of low‐to‐moderate seismicity.
The Valais is the most seismically active region of Switzerland. Strong damaging events occurred in 1755, 1855, and 1946. Based on historical documents, we discuss two known damaging events in the sixteenth century: the 1524 Ardon and the 1584 Aigle earthquakes. For the 1524, a document describes damage in Ardon, Plan-Conthey, and Savièse, and a stone tablet at the new bell tower of the Ardon church confirms the reconstruction of the bell tower after the earthquake. Additionally, a significant construction activity in the Upper Valais churches during the second quarter of the sixteenth century is discussed that however cannot be clearly related to this event. The assessed moment magnitude Mw of the 1524 event is 5.8, with an error of about 0.5 units corresponding to one standard deviation. The epicenter is at 46.27 N, 7.27 E with a high uncertainty of about 50 km corresponding to one standard deviation. The assessed moment magnitude Mw of the 1584 main shock is 5.9, with an error of about 0.25 units corresponding to one standard deviation. The epicenter is at 46.33 N and 6.97 E with an uncertainty of about 25 km corresponding to one standard deviation. Exceptional movements in the Lake Geneva wreaked havoc along the shore of the Rhone delta. The large dimension of the induced damage can be explained by an expanded subaquatic slide with resultant tsunami and seiche in Lake Geneva. The strongest of the aftershocks occurred on March 14 with magnitude 5.4 and triggered a destructive landslide covering the villages Corbeyrier and Yvorne, VD.
The seismic record of recent sediments of the Rhone delta in Lake Geneva (Switzerland, France) presents a discontinuity over a large area of the delta. Previous studies hypothesized that sediments inducing this discontinuity could originate from a giant rock fait (named Tauredunumj that occurred in the Lake Geneva watershed in 583 AD. To verify this hypothesis, two long cores have been retrieved from the lake sediments in the region where the sediment pile thickness is reduced. The sediment sequence presented three major units, with an upper, fine grained and laminated sediments (Unit A), and intermediate unit consisting of altemating coarse and fine grained sediments (Unit B), and a lower unit (Unit C) with sediment characteristics comparable to Unit (A). Unit B was interpreted as sediments inducing the seismic discontinuity. Two organic remains were sampled in Unit B and Unit A, and dated by AMS 14C to 1390-1440 cal. AD and 1680-1780 cal. AD, respectively. The base of Unit B was dated by extrapolation to 1310 cal. AD that is more than six centuries after the Tauredunum rock fait. Moreover, the structure of the intermediate unit was interpreted as a succession of turbidite deposits and hemipelagic sedimentation. The mode of deposition of the sediments and, mainly, the AMS 14C dating of organic remains invalidate the hypothesis of an origin of the intermediate unit in relation to the Tauredunum rock fall. Possible processes are larger inputs (as compared to present time) of detrital material during the "Little/ce Age" and a shift in the sand lobes at the end of sub-lacustrine canyons.
In recent years the upper Rhone Valley has been one of the most intensively investigated regions by the Swiss Seismological Service. The high seismicity in the region encourages research in the seismological field and one main focus has been historical seismology. This report presents the state of the art of our historical investigations by giving an overview of the effects of four damaging earthquakes with intensity larger than VII, for which a fairly large number of documents could be found and analyzed. The overview includes the events of 1584 (Aigle, epicentral intensity VIII), 1755 (Brig, epicentral intensity VIII), 1855 (Visp, epicentral intensity VIII), and 1946 (Sierre, epicentral intensity VIII for the main shock and intensity VII for the largest aftershock). The paper focuses mainly on primary and secondary effects in the epicentral region, providing the key data and a general characterization of the event. Generally, primary effects such as the reaction of the population and impact on buildings took more focus in the past. Thus building damage is more frequently described in historic documents. However, we also found a number of sources describing secondary effects such as landslides, snow avalanches, and liquefaction. Since the sources may be useful, we include citations of these documents. The 1584 Aigle event, for example, produced exceptional movements in Lake Geneva, which can be explained by an expanded sub aquatic slide with resultant tsunami and seiche. The strongest of the aftershocks of the 1584 event triggered a destructive landslide covering the villages Corbeyrier and Yvorne, VD. All macroseismic data on the discussed events are accessible through the webpage of the Swiss Seismological Service (http://www.seismo.ethz.ch).
