Submarine Paleoseismology Based on Turbidite Records

Abstract

Many of the largest earthquakes are generated at subduction zones or other plate boundary fault systems near enough to the coast that marine environments may record evidence of them. During and shortly after large earthquakes in the coastal and marine environments, a spectrum of evidence may be left behind, mirroring onshore paleoseismic evidence. Shaking or displacement of the seafloor can trigger processes such as turbidity currents, submarine landslides, tsunami (which may be recorded both onshore and offshore), and soft-sediment deformation. Marine sites may also share evidence of fault scarps, colluvial wedges, offset features, and liquefaction or fluid expulsion with their onshore counterparts. This article reviews the use of submarine turbidite deposits for paleoseismology, focuses on the dating and correlation techniques used to establish stratigraphic continuity of marine deposits, and outlines criteria for distinguishing earthquake deposits and the strategies used to acquire suitable samples and data for marine paleoseismology.

Turbidite event history—Methods and implications for Holocene paleoseismicity of the Cascadia subduction zone

“…Although analysis of these data has not yet occurred, one obvious conclusion from them is that individual turbidites were clearly imaged in the records and can be linked to the core sites through which they pass. These individual units are traceable for long distances along the margin, demonstrating that while distal turbidites are channelized (for example, Cascadia Channel), proximal turbidites exist as sheet deposits along the base of the continental slope (Goldfinger, 2009(Goldfinger, , 2010(Goldfinger, , 2011a. We find that the correlated reflectors are not strongly linked to canyon/channel systems but apparently have been derived from sheet flows from the continental slope, as well as from the channelized flows we focused on in this study.…”

“…Neither technique uses fault outcrops because the faults are inaccessible, and both techniques must demonstrate that the events they are investigating are generated by earthquakes and not some other natural phenomenon. Nevertheless, these problems can be overcome, and both techniques can be powerful tools for deciphering the earthquake history along an active continental margin (Goldfinger, 2009(Goldfinger, , 2011a. These methods are complementary; the onshore record provides temporal precision for the most recent events by using radiocarbon dating, coral chronology, and dendrochronology (tree-ring dating), whereas the turbidite record extends farther back in time, at least 10,000 years in Cascadia, which is long enough to encompass many earthquake cycles.…”

Key Future Directions For Research On Turbidity Currents and Their Deposits

“…Turbidity currents and their deposits are in some cases an important record of other hazardous events, such as major earthquakes (Goldfinger 2011). However, not every major earthquake appears to produce a widespread sediment flow (Völker et al 2011;Sumner et al 2013b), and there is a need for more studies of the seafloor where it is known that a major earthquake occurred.…”

“…Slower-moving landslides are less tsunamigenic, and will disintegrate and form flows to a lesser extent. There is currently vigorous debate over the extent to which turbidites can be used as a record of major earthquakes (e.g., Goldfinger 2011;Atwater et al 2014), and why some major earthquakes fail to produce extensive slope failure and widespread turbidites (Sumner et al 2013b;Völker et al 2012). Recent work on volcanic island landslides suggests that they can occur in multiple prolonged stages, as shown by associated turbidites with numerous subunits (Hunt et al 2011), thereby reducing tsunami magnitude.…”

Accumulation of an earthquake-induced extremely turbid layer in a terminal basin of the Nankai accretionary prism

“…Sedimentary processes associated with earthquakes are crucial to the understanding of sedimentation systems in a subduction zone. Moreover, paleoseismic histories that can be deduced from sedimentary records and the assessment of tsunami hazards associated with submarine slope failures provide important information for disaster mitigation (e.g., Goldfinger 2011;Yamada et al 2012).…”