Highly variable recurrence of tsunamis in the 7,400 years before the 2004 Indian Ocean tsunami

Abstract

The devastating 2004 Indian Ocean tsunami caught millions of coastal residents and the scientific community off-guard. Subsequent research in the Indian Ocean basin has identified prehistoric tsunamis, but the timing and recurrence intervals of such events are uncertain. Here we present an extraordinary 7,400 year stratigraphic sequence of prehistoric tsunami deposits from a coastal cave in Aceh, Indonesia. This record demonstrates that at least 11 prehistoric tsunamis struck the Aceh coast between 7,400 and 2,900 years ago. The average time period between tsunamis is about 450 years with intervals ranging from a long, dormant period of over 2,000 years, to multiple tsunamis within the span of a century. Although there is evidence that the likelihood of another tsunamigenic earthquake in Aceh province is high, these variable recurrence intervals suggest that long dormant periods may follow Sunda megathrust ruptures as large as that of the 2004 Indian Ocean tsunami.

Using molluscan assemblages from paleotsunami deposits to evaluate the influence of topography on the magnitude of late Holocene mega-tsunamis on Ishigaki Island, Japan

“…The inset photograph shows tsunami deposits T-I and T-II Morales et al 2008;Richmond et al 2011). This is also commonly true of microfossils, such as foraminifera (e.g., Nanayama and Shigeno 2006;Sugawara et al 2009;Rubin et al 2017) and diatoms (e.g., Sawai et al 2009;Goff et al 2012). Kortekaas and Dawson (2007) and Donato et al (2008) found that molluscan assemblages are characterized by a high percentage of articulated bivalve shells if the sediment source includes a bivalve habitat.…”

Modern and historical tropical cyclone and tsunami deposits at the coast of Myanmar: Implications for their identification and preservation in the geological record

“…Numerical models indicate that the 2004 IOT was close to the worst‐case scenario for tsunamis triggered at the North‐Sumatra–Andaman zone (Okal & Synolakis, ; Poisson et al ., ). Geological evidence and slip rate calculations point to a mean recurrence interval of 400 to 600 years for events of similar magnitude (Løvholt et al ., ; Jankaew et al ., ; Brill et al ., ), although the variability of tsunamigenic earthquakes along this segment may cover intervals between less than 100 years and up to 2000 years (Rubin et al ., ).…”

“…Onshore deposits generated by tsunamis and TCs have successfully extended instrumental and historical records in many regions of the world (e.g. Donnelly & Woodruff, 2007;Engel et al, 2016;Garrett et al, 2016;May et al, 2017;Rubin et al, 2017). Under favourable conditions, they may not only provide information about the timing of events, but also about their intensity in terms of flooding extent, flow depth and flow velocity (e.g.…”

The sediment‐fill of Pago Pago Bay (Tutuila Island, American Samoa): New insights on the sediment record of past tsunamis

“…Studying tsunami deposits, like those left behind by the 2009 SPT, is crucial to understanding the impact of such devastating events, including coastal erosion, sediment movement and water flows (Jaffe & Gelfenbaum, 2002;Jaffe & Gelfenbuam, 2007). Knowledge gained from the study of recent deposits can also be used to identify older events in the geological record, thereby helping to reconstruct the palaeo-tsunami record over long periods of time (Pinegina & Bourgeois, 2001;Monecke et al, 2008;Ishimura & Miyauchi, 2015;Rubin et al, 2017). Such information could help to understand the morphological evolution of studied areas and future risk assessment (Atwater, 1987;Jaffe & Gelfenbaum, 2002;Nanayama et al, 2003;Williams et al, 2011).…”