TY - JOUR A1 - Grieve, Stuart W. D. A1 - Hales, Tristram C. A1 - Parker, Robert N. A1 - Mudd, Simon M. A1 - Clubb, Fiona J. T1 - Controls on Zero-Order Basin Morphology JF - Journal of geophysical research : Earth surface N2 - Zero-order basins are common features of soil-mantled landscapes, defined as unchanneled basins at the head of a drainage network. Their geometry and volume control how quickly sediment may reaccumulate after landslide evacuation and, more broadly, zero order basins govern the movement of water and sediment from hillslopes to the fluvial network. They also deliver water and sediment to the uppermost portions of the fluvial network. Despite this role as the moderator between hillslope and fluvial processes, little analysis on their morphology has been conducted at the landscape scale. We present a method to identify zero-order basins in landscapes and subsequently quantify their geometric properties using elliptical Fourier analysis. We deploy this method across the Coweeta Hydrologic Laboratory, USA. Properties such as length, relief, width, and concavity follow distinct probability distributions, which may serve as a basis for testing predictions of future landscape evolution models. Surprisingly, in a landscape with an orographic precipitation gradient and large hillslope to channel relief, we observe no correlation between elevation or spatial location and basin geometry. However, we find that two physiographic units in Coweeta have distinct zero-order basin morphologies. These are the steep, thin soiled, high-elevation Nantahala Escarpment and the lower-gradient, lower-elevation, thick soiled remainder of the basin. Our results indicate that basin slope and area negatively covary, producing the distinct forms observed between the two physiographic units, which we suggest arise through competition between spatially variable soil creep and stochastic landsliding. KW - zero-order basin KW - landslide KW - hillslope geomorphology KW - landscape evolution modeling KW - lidar KW - hillslope sediment transport Y1 - 2018 U6 - https://doi.org/10.1029/2017JF004453 SN - 2169-9003 SN - 2169-9011 VL - 123 IS - 12 SP - 3269 EP - 3291 PB - American Geophysical Union CY - Washington ER - TY - JOUR A1 - Fan, Xuanmei A1 - Scaringi, Gianvito A1 - Korup, Oliver A1 - West, A. Joshua A1 - van Westen, Cees J. A1 - Tanyas, Hakan A1 - Hovius, Niels A1 - Hales, Tristram C. A1 - Jibson, Randall W. A1 - Allstadt, Kate E. A1 - Zhang, Limin A1 - Evans, Stephen G. A1 - Xu, Chong A1 - Li, Gen A1 - Pei, Xiangjun A1 - Xu, Qiang A1 - Huang, Runqiu T1 - Earthquake-Induced Chains of Geologic Hazards BT - Patterns, Mechanisms, and Impacts JF - Reviews of geophysics N2 - Large earthquakes initiate chains of surface processes that last much longer than the brief moments of strong shaking. Most moderate‐ and large‐magnitude earthquakes trigger landslides, ranging from small failures in the soil cover to massive, devastating rock avalanches. Some landslides dam rivers and impound lakes, which can collapse days to centuries later, and flood mountain valleys for hundreds of kilometers downstream. Landslide deposits on slopes can remobilize during heavy rainfall and evolve into debris flows. Cracks and fractures can form and widen on mountain crests and flanks, promoting increased frequency of landslides that lasts for decades. More gradual impacts involve the flushing of excess debris downstream by rivers, which can generate bank erosion and floodplain accretion as well as channel avulsions that affect flooding frequency, settlements, ecosystems, and infrastructure. Ultimately, earthquake sequences and their geomorphic consequences alter mountain landscapes over both human and geologic time scales. Two recent events have attracted intense research into earthquake‐induced landslides and their consequences: the magnitude M 7.6 Chi‐Chi, Taiwan earthquake of 1999, and the M 7.9 Wenchuan, China earthquake of 2008. Using data and insights from these and several other earthquakes, we analyze how such events initiate processes that change mountain landscapes, highlight research gaps, and suggest pathways toward a more complete understanding of the seismic effects on the Earth's surface. KW - earthquake-induced landslides KW - debris flows KW - geohazards KW - landscape evolution KW - sediment cascade KW - continental earthquakes Y1 - 2019 U6 - https://doi.org/10.1029/2018RG000626 SN - 8755-1209 SN - 1944-9208 VL - 57 IS - 2 SP - 421 EP - 503 PB - American Geophysical Union CY - Washington ER -