Abstract
Subduction megathrusts host the Earth’s greatest earthquakes as the 1960 Valdivia (Mw 9.5, Chile), the largest earthquake instrumentally recorded, and the recent 2004 Sumatra-Andaman (Mw 9.2, Indonesia), 2010 Maule (Mw 8.8, Chile), and 2011 Tohoku-Oki (Mw 9.1, Japan) earthquakes triggering devastating tsunamis and representing a major hazard to society. Unravelling the spatio-temporal pattern of these events is thus a key for seismic hazard assessment of subduction zones. This paper reviews the current state of knowledge of two research areas–empirical analysis of global-scale natural data and experimental data from an analogue seismotectonic modelling—devoted to study cause-effect relationships between subduction zone parameters and the megathrust seismogenic behavior. The combination of the two approaches overcomes the observational bias and inherent sampling limitations of geological processes (i.e., shortness of instrumental and historical data, decreasing completeness and resolution with time into the past) and allows drawing appropriately from multiple disciplines with the aim of highlighting the geodynamic conditions that may favor the occurrence of giant megathrust earthquakes.
Highlights
Most of the global seismicity and the largest earthquakes occur at subduction zones where oceanic lithosphere is recycled as it sinks into the underlying mantle
The instrumental seismic record is limited to the last century, a very short time interval compared to the recurrence time of great earthquakes, which ranges from centuries to millennia (e.g., McCaffrey, 2008)
We focus our brief overview on the state of the art of the analysis from global-scale natural data and experimental data from analogue seismotectonic modelling, highlighting the advantages of their use and the great potential for future developments in the study of the earthquake process that can be drawn from the close interaction and reciprocal feedback between the two methods
Summary
Most of the global seismicity and the largest earthquakes occur at subduction zones where oceanic lithosphere is recycled as it sinks into the underlying mantle. Empirical Subduction Zone Seismicity Analysis increased rate with respect to the last century (e.g., Ammon et al, 2010) often revealing unexpected characteristics (e.g., Stein and Okal 2011; Yue and Lay 2013) and resulting in catastrophic direct and indirect (e.g., tsunamis) effects as in Sumatra (2004) (e.g., Subaraya et al, 2006), and Tohoku-Oki 2011 (e.g., Romano et al, 2012) The attention for these events has recently increased, raising interest on factors controlling their spatio-temporal pattern, including their potential maximum magnitude and return periods which are fundamental parameters in earthquake and tsunami hazard assessment. While numerical simulations proved useful for testing hypothesis and mapping a wide parameter space, it is the emergent behavior of analogue models which makes them appealing for an empirical analysis as addressed in this review
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