Lake sediments as natural seismographs: A compiled record of Late Quaternary earthquakes in Central Switzerland and its implication for Alpine deformation

Abstract

Central Switzerland lies tectonically in an intraplate area and recurrence rates of strong earthquakes exceed the time span covered by historic chronicles. However, many lakes are present in the area that act as natural seismographs: their continuous, datable and high‐resolution sediment succession allows extension of the earthquake catalogue to pre‐historic times. This study reviews and compiles available data sets and results from more than 10 years of lacustrine palaeoseismological research in lakes of northern and Central Switzerland. The concept of using lacustrine mass‐movement event stratigraphy to identify palaeo‐earthquakes is showcased by presenting new data and results from Lake Zurich. The Late Glacial to Holocene mass‐movement units in this lake document a complex history of varying tectonic and environmental impacts. Results include sedimentary evidence of three major and three minor, simultaneously triggered basin‐wide lateral slope failure events interpreted as the fingerprints of palaeoseismic activity. A refined earthquake catalogue, which includes results from previous lake studies, reveals a non‐uniform temporal distribution of earthquakes in northern and Central Switzerland. A higher frequency of earthquakes in the Late Glacial and Late Holocene period documents two different phases of neotectonic activity; they are interpreted to be related to isostatic post‐glacial rebound and relatively recent (re‐)activation of seismogenic zones, respectively. Magnitudes and epicentre reconstructions for the largest identified earthquakes provide evidence for two possible earthquake sources: (i) a source area in the region of the Alpine or Sub‐Alpine Front due to release of accumulated north‐west/south‐east compressional stress related to an active basal thrust beneath the Aar massif; and (ii) a source area beneath the Alpine foreland due to reactivation of deep‐seated strike‐slip faults. Such activity has been repeatedly observed instrumentally, for example, during the most recent magnitude 4·2 and 3·5 earthquakes of February 2012, near Zug. The combined lacustrine record from northern and Central Switzerland indicates that at least one of these potential sources has been capable of producing magnitude 6·2 to 6·7 events in the past.

Historical seismicity of the Mont Dore volcanic province (Auvergne, France) unraveled by a regional lacustrine investigation: New insights about lake sensitivity to earthquakes

“…Among this volume, 56,000 m 3 may correspond to the 70 cm thick silty deposit identified at the top of the MWD. In core CHA13-7B, the sandy base and the fining upward sequence identified in unit T, in addition to a white lamina at its top, constitute evidences for a sedimentary event deposited during one short-term episode of turbidity current (i.e., turbidite, e.g., St-Onge et al, 2004;Strasser et al, 2013). The base-to-top decrease in sorting and skewness values indicates a decreasing energy during deposition at core site (Fig.…”

“…Over the last decades, lake sediments have been analyzed for their relevance to record seismic events and have been successfully used as natural seismographs for long-term record of earthquake-induced sedimentary disturbances (Strasser et al, 2013). Today, many studies use various forms of instantaneously formed sedimentary deposits or structures for qualitative and quantitative earthquake reconstructions in lacustrine systems during the Holocene, as long as the seismic origin of these deposits is clear.…”

“…Today, many studies use various forms of instantaneously formed sedimentary deposits or structures for qualitative and quantitative earthquake reconstructions in lacustrine systems during the Holocene, as long as the seismic origin of these deposits is clear. Most of these studies are concentrated in tectonically active regions such as the Alps (Beck et al, 1996;Schnellmann et al, 2002;Monecke et al, 2004;Nomade et al, 2005;Strasser et al, 2006Strasser et al, , 2013Wilhelm et al, 2015;Chapron et al, 2016), the Anatolian fault (Schwab et al, 2009;Avşar et al, 2014Avşar et al, , 2015 and around the Pacific where recurrent and large earthquakes have been recently experienced such as in Chile (Chapron et al, 2006;Bertrand et al, 2008;Moernaut et al, 2007Moernaut et al, , 2014, US western coast (Karlin et al, 2004;Maloney et al, 2013;Morey et al, 2013;Smith et al, 2013), Japan (Inouchi et al, 1996) or New Zealand (Howarth et al, 2014;Gomez et al, 2015). Moreover, recent limnogeological investigations in glacial lakes of the mid-continental North America underline the ability of sediment to archive earthquakes throughout the Holocene, despite the low to moderate magnitude of earthquakes that occurred in this intraplate domain (St-Onge et al, 2004;Doughty et al, 2014;Lajeunesse et al, in press;Locat et al, 2016).…”

A multi-centennial record of past floods and earthquakes in Valle d'Aosta, Mediterranean Italian Alps

“…return period of ∼ 35 years) suggests a high sensitivity of Lago Inferiore de Laures to earthquake shaking, as such a high frequency of earthquake-induced deposits has rarely been observed in the region (e.g. Guyard et al, 2007;Lauterbach et al, 2012;Simonneau et al, 2013;Strasser et al, 2013;Kremer et al, 2015;Chapron et al, 2016;Wilhelm et al, 2016b). All historical earthquakes are plotted in a "distance vs. epicentral MSK intensity" diagram (e.g.…”

“…Among them, lake sediments have shown to be valuable archives as they record past events in a continuous and high-resolution mode (e.g. Lauterbach et al, 2012;Wilhelm et al, 2012a;Strasser et al, 2013;Wirth et al, 2013;Amman et al, 2015;Van Daele et al, 2015). The greater hydraulic energy of flooded rivers increases their capacity to erode and transport sediments.…”