Non-volcanic Tremor: A Window into the Roots of Fault Zones

Abstract

The recent discovery of non-volcanic tremor in Japan and the coincidence of tremor with slow-slip in Cascadia have made earth scientists reevaluate our models for the physical processes in subduction zones and on faults in general. Subduction zones have been studied very closely since the discovery of slow-slip and tremor. This has led to the discovery of a number of related phenomena including low frequency earthquakes and very low frequency earthquakes. All of these events fall into what some have called a new class of events that are governed under a different frictional regime than simple brittle failure. While this model is appealing to many, consensus as to exactly what process generates tremor has yet to be reached. Tremor and related events also provide a window into the deep roots of subduction zones, a poorly understood region that is largely devoid of seismicity. Given that such fundamental questions remain about non-volcanic tremor, slow-slip, and the region in which they occur, we expect that this will be a fruitful field for a long time to come.

Teleseismic constraints on the geological environment of deep episodic slow earthquakes in subduction zone forearcs: A review

“…1), although there may be a gap between the slow earthquake source region and the seismogenic zone in some cases (Hyndman et al, 2015). Their occurrence may be induced by fluid flow and fluid processes at the plate interface and within the overlying plate (Rubinstein et al, 2010, and references therein). Low frequency earthquakes (LFEs) have also been observed in coincidence with the slow slip and tremor in subduction zones, with focal mechanism and location consistent with interplate slip (Shelly et al 2006(Shelly et al , 2007.…”

“…Several reviews on the observations of slow earthquakes have been published recently (Beroza and Ide, 2011;Gomberg et al, 2010;Rubinstein et al, 2010;Schwartz and Rokowski, 2007). In this review we focus on the structural and geological environment in which slow earthquakes occur as inferred primarily from teleseismic studies.…”

Multiple damage zone structure of an exhumed seismogenic megasplay fault in a subduction zone - a study from the Nobeoka Thrust Drilling Project

“…The slip budget within seismogenic zones in subduction settings is accommodated by coseismic slip, aseismic creep, lowfrequency earthquakes, episodic volcanic/non-volcanic tremor, and slow slip events that occur along plate boundary faults (e.g., Ito and Obara 2006;Rubinstein et al 2010). The width of the deformation zone is one of the parameters that characterize the mode of fault slip, frictional instability, displacement, and fault evolution (e.g., Rice et al 2014).…”

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“…Only since the advent of dense, plate boundary-scale geodetic networks in the last decade has the importance of these events as a significant mode of fault slip been recognized. The observation of SSEs and associated seismic phenomena at subduction megathrusts worldwide (see review in Schwartz and Rokosky, 2007) has ignited one of the most dynamic fields of research in seismology today (e.g., Rubinstein et al, 2010;Peng and Gomberg, 2010;Wech and Creager, 2011). Although SSEs appear to bridge the gap between typical earthquake behavior and steady, aseismic slip on faults, the physical mechanisms that lead to SSEs and their relationship to destructive, seismic slip on subduction thrusts are poorly known.…”