Effects of strong seismic shaking in lake sediments, and earthquake recurrence interval, Témiscaming, Quebec

Abstract

The magnitude 6.3 Timiskaming earthquake of 1935 resulted in discoloration in small lakes in the epicentral region. Sonar profiles for Lac Tee have shown that organic-rich gyttja has been removed from the sides and redeposited in the deep parts of the lake. Lake sediment cores from deep basins contain a 2–3 cm uppermost layer, which is interpreted as the normal accumulation of sediment since 1935. This is followed by a 20 cm chaotic zone of black gyttja mixed with partly tabular fragments of a previously formed silt layer, underlain by a dense 1–2 cm thick silt horizon. The latter is interpreted as having formed by rapid settling of the denser silicate portion of the resuspended sediment. This 20 cm zone is insufficient to account for the abnormal thickness of gyttja in the basins, so events of this kind would have had to have occurred repeatedly since deglaciation. The only major prehistoric event revealed by these ~100 cm cores is at a depth equivalent to about 1500 years ago, based on the amount of sediment deposited since 1935. A minor silting event occurred about 400 years ago. On this basis, the recurrence interval of magnitude 6 or greater earthquakes is longer at Témiscaming than at Charlevoix, Quebec (75 years historically), consistent with the present relative frequency of small earthquakes in these two regions.

Are great Cascadia earthquakes recorded in the sedimentary records from small forearc lakes?

“…The ages of the silt layers support the notion that they resulted from five historic earthquakes on nearby crustal faults (Doig, 1986(Doig, , 1991. The most common explanation for the presence of silt layers in sediment from Oregon and Washington lakes has been increased sediment transport from sources external to the lake, however subsequent investigations suggests these deposits result from shaking-induced failures.…”

“…The time span represented by these records is variable, but frequently surpasses 10 000 yr. Lacustrine turbidite palaeoseismology has been used to reconstruct earthquake chronologies around the world, including Switzerland (Schnellman et al, 2002;Arnaud et al, 2006;Strasser et al, 2006), Chile, (Arnaud et al, 2006;Moernaut et al, 2007;Bertrand et al, 2008;Charlet et al, 2008), Argentina (Waldmann et al, 2008), Venezuela (Carrillo et al, 2008), France (Chapron et al, 1999;Arnaud et al, 2002;Guyard et al, 2007;Beck, 2009), Kyrghyzstan (Bowman et al, 2004), Japan, (Shiki et al, 2000a), Russia (Nelson et al, 1995), Canada (Doig, 1986(Doig, , 1990(Doig, , 1991, New Zealand (Orpin et al, 2010;Howarth et al, 2012), California (Smoot et al, 2000;Seitz and Kent, 2005;Kent et al, 2005;Brothers et al, 2009), Arizona (Twitchell et al, 2005), as well as in the vicinity of the CSZ at Lake Washington, USA (Karlin et al, 2004;Abella, 1992, 1996). In favourable settings, reconstructions can reach 50 000 yr (late-Pleistocene Lake Lisan, palaeo-Dead Sea; Marco et al, 1996).…”

Seismically-triggered organic-rich layers in recent sediments from Göllüköy Lake (North Anatolian Fault, Turkey)

“…These resuspended sediments, generally organic rich, are deposited at distal parts of lakes with a gravitational segregation of the clastic and organic fractions; e.g. silt layer overlain by organic rich layer (Siegenthaler et al, 1987;Doig, 1990;1991;1998a;1998b). This mechanism is probably limited to environments having almost clay-free deposits because cohesive clayey-mud is unlikely to be resuspended by water oscillations.…”

Sedimentary records of past earthquakes in Boraboy Lake during the last ca 600 years (North Anatolian Fault, Turkey)

“…Moreover, seismicallyinduced water oscillations (i.e., seiche) may cause in-situ sediment resuspension and redeposition (e.g., Siegenthaler et al, 1987;Doig, 1990;1991;1998a;1998b), or transportation of material from lake shores (e.g., Avşar et al, 2014b). In addition to subaqueous mass-wasting, earthquakes may trigger landslides in lake catchments, which may enhance sediment flux into lakes and leave sedimentary traces in the sequence (e.g., Leroy et al, 2009;Hubert-Ferrari et al, 2012;Avşar et al, 2014a;Howarth et al, 2012;.…”