Subduction-zone processes play a central role in shaping the land- and sea-scapes along convergent plate margins. Storms and earthquake-shaking mobilize rocks, sediment and soil, which are continuously transported seaward by the ebb and flow of flooding rivers and offshore currents. Catastrophic and punctuated erosional pulses across land- and sea-scapes can initiate complicated responses and continuous adjustments that persist for years or even decades following the events that precipitated the geomorphic cascade. Slope failures from volcanic sector collapse, earthquake land-level changes, and storms can all dam river channels, leading to continuous adjustments in response to changes in sediment supply, or outburst floods that rapidly alter river channel morphology – both of which can impact downstream communities. The generation of large volumes of detritus from subduction-zone disturbances can modify river networks for decades to years, changing both their forms and processes in ways that may produce more frequent flooding and promote channel widening.  Faulting and folding of rock lying within the region between the subduction trench and the volcanic arc can build topography and produce earthquakes, whose proximity to humans and their enterprises makes them especially potent hazards.

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Understanding these disturbances and their cascading impacts have enormous practical importance because they pose substantial risks to the ecosystems, communities, and infrastructure within subduction-zone land- and sea-scapes. Despite this, we still lack understanding of the controls on the amount of subduction-zone convergence that is taken up between the trench and arc, when catastrophic surface disturbances might be initiated, where the detritus produced by these events might go, and how long and far the cascading impacts that are produced by these disturbances might extend.

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