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1. Imaging the Garlock Fault Zone With a Fiber: A Limited Damage Zone and Hidden Bimaterial Contrast

   https://doi.org/10.1029/2024JB028900  

   Atterholt, James; Zhan, Zhongwen; Yang, Yan; Zhu, Weiqiang (July 2024, Journal of Geophysical Research: Solid Earth)

   Abstract The structure of fault zones and the ruptures they host are inextricably linked. Fault zones are narrow, which has made imaging their structure at seismogenic depths a persistent problem. Fiber‐optic seismology allows for low‐maintenance, long‐term deployments of dense seismic arrays, which present new opportunities to address this problem. We use a fiber array that crosses the Garlock Fault to explore its structure. With a multifaceted imaging approach, we peel back the shallow structure around the fault to see how the fault changes with depth in the crust. We first generate a shallow velocity model across the fault with a joint inversion of active source and ambient noise data. Subsequently, we investigate the fault at deeper depths using travel‐time observations from local earthquakes. By comparing the shallow velocity model and the earthquake travel‐time observations, we find that the fault's low‐velocity zone below the top few hundred meters is at most unexpectedly narrow, potentially indicating fault zone healing. Using differential travel‐time measurements from earthquake pairs, we resolve a sharp bimaterial contrast at depth that suggests preferred westward rupture directivity. 

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2. REWTCrunch: A Modeling Framework for Vegetation Induced Reactive Zone Processes in the Critical Zone

   https://doi.org/10.1029/2021JG006562  

   Roque‐Malo, Susana; Druhan, Jennifer L.; Kumar, Praveen (February 2022, Journal of Geophysical Research: Biogeosciences)

   Abstract Vegetation optimizes its geochemical environment for resource management via root exudation. We refer to the soil zone where biogeochemical behavior is significantly influenced, directly or indirectly, by root processes as the vegetation induced reactive zone (VIRZ). Root exudates react with VIRZ soil substrates creating temporally variable chemical environments through depth that extend below the rooting zone, impacting weathering, and releasing solutes and gases. We present a new framework, REWTCrunch, to capture VIRZ dynamics by integrating three modeling advances: the multicomponent reactive transport model CrunchFlow, the root exudation model REWT, and the multilayer canopy‐root ecohydrologic model MLCan. REWTCrunch's high‐resolution, process‐based simulation of root exudation, and the transport and transformation of carbon (C) and nutrients according to mass‐balanced and charge‐balanced reaction networks gives new insight into vertically resolved root‐soil‐microbe‐water interactions and their influence on solute fluxes at a daily timescale. We benchmark REWT and CrunchFlow, illustrate coupling mechanisms, and present REWTCrunch simulations for an agricultural site in the US Midwest. Results demonstrate root‐sourced reactive C can augment or reduce solute concentrations in the soil by several orders of magnitude. Silicate weathering products illustrate after‐harvest effects of plant C inputs in leaching patterns. Calcium simulations reveal the development of a stable weathering front. Aluminum concentrations are particularly responsive to root‐sourced reactivity, and analysis of leaching concentration versus leaching flux indicates hysteresis behavior. REWTCrunch significant improves our ability to simulate the link between root processes and soil biogeochemistry, thereby filling an important gap in the numerical simulation of root processes, weathering, and long‐term soil health. 

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3. Can a barrier zone stop invasion of a population?

   https://doi.org/10.1007/s00285-020-01541-7  

   Li, Bingtuan; Zhang, Minghua; Coffman, Bradley (November 2020, Journal of Mathematical Biology)
4. Hyporheic zone influences on concentration-discharge relationships in a headwater sandstone stream: HYPORHEIC ZONE AND CQ

   https://doi.org/10.1002/2016WR019717  

   Hoagland, Beth; Russo, Tess A.; Gu, Xin; Hill, Lillian; Kaye, Jason; Forsythe, Brandon; Brantley, Susan L. (June 2017, Water Resources Research)
5. Animating the critical zone: beavers as critical zone engineers

   https://doi.org/10.3389/frwa.2025.1547094  

   Adamchak, Clifford; Lininger, Katherine B; Hinckley, Eve-Lyn S (February 2025, Frontiers in Water)

   Beavers (Castor canadensis) have not been adequately included in critical zone research, yet they can affect multiple critical zone processes across the terrestrial-aquatic interface of river corridors. River corridors (RC) provide a disproportionate amount of ecosystem services. Over time, beaver activity, including submersion of woody vegetation, burrowing, dam building, and abandonment, can impact critical zone processes in the river corridor by influencing landscape evolution, biodiversity, geomorphology, hydrology, primary productivity, and biogeochemical cycling. In particular, they can effectively restore degraded riparian areas and improve water quality and quantity, causing implications for many important ecosystem services. Beaver-mediated river corridor processes in the context of a changing climate require investigation to determine how both river corridor function and critical zone processes will shift in the future. Recent calls to advance river corridor research by leveraging a critical zone perspective can be strengthened through the explicit incorporation of animals, such as beavers, into research projects over space and time. This article illustrates how beavers modify the critical zone across different spatiotemporal scales, presents research opportunities to elucidate the role of beavers in influencing Western U.S. ecosystems, and, more broadly, demonstrates the importance of integrating animals into critical zone science. 

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