Supplementary material to "1997 Kronotsky earthquake and tsunami and their predecessors, Kamchatka, Russia"

Abstract

Kronotsky earthquake and tsunami and their predecessors, Kamchatka, Russia Earthquake and tsunami dataThis supplement includes a reproduction of the original figure by Gusev (2004) of source regions for large Kamchatka earthquakes since 1899 (Fig. S1). In our paper, we use a revised version of this figure and discuss the bases for our suggested revisions.Tsunamis have arrived to Kamchatka not only from local earthquakes but also from other regions, of which Kamchatka is particularly susceptible to tsunamis from Chile; Kamchatka is shadowed (protected) from nonlocal tsunamis originating in the North Pacific (Table S1; localities on Fig. S2). In order to interpret 20 th century tsunami deposits in our field sites, we use these data to evaluate the possibility that at least one of the deposits is from a far-field event, Chile 1960. Table S2 provides a summary of different researchers' assignments of moment magnitude, locations of mainshock epicenter and hypocenter, and centroid determinations for the December 1997 Kronotsky earthquake. There are some significant differences, which we discuss in our paper in terms of our documented evidence for tsunami runup averaging about 6 m along the coast north of Kronotsky Peninsula. Figure S3 is a version of a previously published photo and sketch interpretation of 1997 Kronotsky tsunami effects on Kronotsky Cape (Pinegina et al., 2003).The magnitudes of tsunamigenic and other large earthquakes originating along the Kamchatka subduction zone (and to its north) have been evaluated by Gusev and Shumilina (2004), with some suggested revisions to other catalogues (Table S3). One indicator of moment magnitude of earthquakes originating along the KurilKamchatka subduction zone is their tide-gage amplitude in Hilo, Hawaii, as shown in Table S3 for all historical earthquakes and in Figure S4 for events with a tide-gage record in Hilo.In A.D. 1923, there were two tsunamigenic earthquakes along the northern Kamchatka subduction zone. Table S4 is a compilation of information about those two tsunamis, which both affected Kamchatsky Bay. These observations and data help us evaluate which of these two tsunamis may have affected our field area in south Kamchatsky Bay. Methodology for reconstructing paleoshorelines (Figure S5)Many profiles show evidence of changes through time in beach-plain width and in surface elevation relative to sea level; that is, the shoreward, older parts of profiles are higher or lower than the seaward parts ( Figure S5). Ideally, a reconstruction of the prehistoric coast and hence of paleotsunami size (runup and inundation as approximated by deposit extent) will include an estimate of horizontal shifts of shoreline location for paleoinundation and an approximation of change in relative sea level for paleo-runup. We use tephra stratigraphy (as in Pinegina et al., 2013;MacInnes et al., 2016) and tephra mapping along profiles in order to reconstruct paleoprofiles. The reconstruction of the south Kamchatsky Bay profiles and their paleotsunamis was first performed and r...