Lake-sediment based paleoseismology: Limitations and perspectives from the Swiss Alps

Kremer, Katrina; Wirth, Stefanie B.; Reusch, Anna; Fäh, Donat; Bellwald, Benjamin; Anselmetti, Flavio S.; Girardclos, Stéphanie; Strasser, Michael

doi:10.1016/j.quascirev.2017.04.026

Cited by 73 publications

(89 citation statements)

References 60 publications

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“…Also the prehistoric event B, dated to 2250 cal yr B.P., might be linked to the well documented ~2200 cal yr B.P. earthquake (Kremer et al, ; Monecke et al, ; Strasser et al, ). This study at Lake Oeschinen shows that it might have had the potential to trigger rockfalls in the Bernese Oberland, which is also supported by Köpfli et al ().…”

Section: Discussionmentioning

confidence: 97%

Multistage Rock‐Slope Failures Revealed in Lake Sediments in a Seismically Active Alpine Region (Lake Oeschinen, Switzerland)

et al. 2018

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Late Glacial and Holocene rock‐slope failures occur often as multistage failures where paraglacial adjustment and stress adaptation are hypothesized to control phases of detachment. However, only limited data sets are available to decipher large multistage rock‐slope failures in detail. Here we apply sedimentology, radiocarbon dating, and geophysics to reconstruct multistage rock‐slope failure recorded in lake sediments. We present a unique inventory from Lake Oeschinen (Bernese Alps, Switzerland) covering ~2.5 kyr of rock‐slope failure history. The lake sediments have been investigated using sediment‐core analysis, radiocarbon dating, and seismic‐to‐core and core‐to‐core correlations, which were linked to (pre‐) historic and meteorological records. The results imply that the lake in its present extent is significantly younger than the ~9.5‐kyr‐old Kandersteg rock avalanche in the close vicinity. Up to eleven rock‐slope failure events could be identified and related to specific detachment scarps, which provided information for energy considerations. Four events likely coincided with (pre‐) historic earthquakes. At least six events detached from the same area, potentially initiated by prehistoric seismicity and later from stress‐relaxation processes. The data imply unexpected high recurrence rates (~1/300 years) and also help to understand the generation of a historical lake‐outburst flood. Here we show how polymethodical analysis of lake sediments can help to decipher massive multistage rock‐slope failures, which are often camouflaged in subaerial settings.

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Section: Discussionmentioning

confidence: 97%

Multistage Rock‐Slope Failures Revealed in Lake Sediments in a Seismically Active Alpine Region (Lake Oeschinen, Switzerland)

et al. 2018

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“…Thousands of years later, these imprints can remain preserved in the sedimentary infill of the basin. Moreover, epicenter locations and magnitudes of the responsible earthquakes have been estimated based on the appearance of simultaneously deposited landslides in different lakes (Kremer et al, 2017;Strasser et al, 2006). In some cases, observed MTDs in lakes and other basins could even be attributed to major prehistorical earthquakes linked to activated faults (Carrillo et al, 2008;McHugh et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

“…In some cases, observed MTDs in lakes and other basins could even be attributed to major prehistorical earthquakes linked to activated faults (Carrillo et al, 2008;McHugh et al, 2006). Moreover, epicenter locations and magnitudes of the responsible earthquakes have been estimated based on the appearance of simultaneously deposited landslides in different lakes (Kremer et al, 2017;Strasser et al, 2006). In many cases, these studies combine sediment cores with high-resolution seismic data, allowing identification, mapping, and dating of MTDs, as well as determination of their geographical and temporal distribution.…”

Section: Introductionmentioning

confidence: 99%

Holocene Event Record of Aysén Fjord (Chilean Patagonia): An Interplay of Volcanic Eruptions and Crustal and Megathrust Earthquakes

et al. 2018

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In the first months of 2007, the Aysén region in southern Chile was affected by a crustal seismic swarm. Its largest earthquake (Mw 6.2) occurred in April and had its epicenter in Aysén Fjord. Seismic intensities became so high that hundreds of onshore mass movements were triggered, several of which entered into the fjord, resulting in mass transport deposits (MTDs) preserved at the fjord bottom. Here we present a Holocene record of paleo‐earthquakes in the previously unstudied Patagonian fjordland based on MTD stratigraphy. High‐resolution seismic data retrieved using two different seismic systems (sparker and TOPAS) reveal multiple older MTDs on different stratigraphic levels. Correlation of the seismic stratigraphy with sedimentological data obtained from a long Calypso core (MD07‐3117) allows conclusion on the seismic origin of these deposits. Additionally, radiocarbon dating permits constructing an age model, validated by tephrochronology, providing an age for the different MTD levels. We thus present a highly detailed paleoseismological history of the Aysén region, including at least six major Holocene earthquakes, one of which is likely related to a known megathrust earthquake. Other earthquakes are related to activity of the Liquiñe‐Ofqui Fault Zone (LOFZ), forming the main source of seismic hazard in the area. We can infer a general average recurrence time for LOFZ earthquakes of ~2,100 years in the vicinity of Aysén Fjord with clustered events during the early and late Holocene. Finally, we argue that cascading events (causal link between volcanic and seismic events) may be a frequent phenomenon along the LOFZ.

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“…Strasser et al () reconstruct magnitudes and epicenter locations for historical earthquakes in the Swiss Alps by using subaqueous landslide deposits simultaneously present in the sedimentary record of two lakes, or absent in one of them, that is, positive and negative shaking evidence. Kremer et al () elaborate the previous study with more paleolacustrine records and also evaluate the influence of using different upper threshold values when no MTDs are triggered. In this study, we develop a probabilistic method to determine the most likely earthquake source(s) for a distribution of sites with positive and negative evidence of coseismic MTDs.…”

Section: Introductionmentioning

confidence: 99%

Probabilistic Evaluation of Fault Sources Based on Paleoseismic Evidence From Mass‐Transport Deposits: The Example of Aysén Fjord, Chile

2018

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Contemporaneous mass‐transport deposits (MTDs) recorded in lake and fjord sediments provide evidence of past seismic shaking. However, because they are usually not connected to a fault rupture, assessment of the earthquake source remains difficult. Based on observed coseismic mass wasting and associated seismic shaking, previous studies assigned minimum intensities required to trigger them. Attempts to infer their earthquake source relied on methods developed to estimate the location and magnitude of historical earthquakes using intensity prediction equations, but considered these thresholds as actual intensities. Here we develop a probabilistic method to infer the most likely earthquake sources from the spatial distribution (or absence) of MTDs. This approach simultaneously allows the triggering intensity to exceed the assumed threshold and takes into account intensity prediction equation uncertainties, two shortcomings of existing methods. Additionally, we consider known active faults rather than a grid of possible epicenters. We apply this method to Aysén Fjord (southern Chile), which is intersected by the Liquiñe‐Ofqui Fault Zone. In 2007, an MW = 6.2 earthquake hit the fjord with intensities of VIII+, causing major landslides entering the fjord. Seismic‐reflection profiles show that its sedimentary fill contains nine prehistoric MTD levels. Following a sensitivity analysis, application of the method to the MTD record allows identifying the most likely fault sections and magnitude range for most events, confirming that they are mainly attributed to crustal earthquakes on the Liquiñe‐Ofqui Fault Zone. We conclude that the method has good potential to constrain the size and location of paleoearthquakes for which only shaking evidence is available.

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Lake-sediment based paleoseismology: Limitations and perspectives from the Swiss Alps

Cited by 73 publications

References 60 publications

Multistage Rock‐Slope Failures Revealed in Lake Sediments in a Seismically Active Alpine Region (Lake Oeschinen, Switzerland)

Multistage Rock‐Slope Failures Revealed in Lake Sediments in a Seismically Active Alpine Region (Lake Oeschinen, Switzerland)

Holocene Event Record of Aysén Fjord (Chilean Patagonia): An Interplay of Volcanic Eruptions and Crustal and Megathrust Earthquakes

Probabilistic Evaluation of Fault Sources Based on Paleoseismic Evidence From Mass‐Transport Deposits: The Example of Aysén Fjord, Chile

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