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.  The Land- and Sea-Scapes component of the SZ4D proposes to leverage a suite of new observational technologies, computational capabilities, and algorithmic developments to address the following key research questions:

Can we anticipate the impacts of great subduction zone earthquakes and volcanic eruptions on sediment generation and transport across landscapes and seascapes?

• What are the fundamental controls on the initiation and runout of landslides, turbidity currents, and volcanic mudflows?

• How do surface processes produce cascading and persistent impacts as material is transported across the land- and sea-scape?

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What fraction of a subduction zone’s energy budget goes into building and shaping subduction zone land- and seascapes?

• How much permanent deformation is absorbed in the forearc and what factors control this?

• How do upper plate structures that modify land- and seascapes contribute to subduction zone hazards?

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* Steering Committee Member

June 2020 Webinar
Planning for the SZ4D Initiative: Meet the Landscapes & Seascapes Working Group

Interest Group Contacts:

Alison Duvall - aduvall@uw.edu

George Hilley - hilley@stanford.edu