Earthquakes drive focused denudation along a tectonically active mountain front

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.

show abstract

“…• Focusing denudation along seismically active mountain fronts (Li et al, ) reorganizing drainage basins (Dahlquist et al, ; Hovius et al, )…”

Section: The Lasting Legacy Of Eqtlsmentioning

confidence: 99%

Earthquake‐Induced Chains of Geologic Hazards: Patterns, Mechanisms, and Impacts

Fan

Scaringi

Korup

et al. 2019

Reviews of Geophysics

Self Cite

618

325

View full text Add to dashboard Cite

show abstract

“…Geophysical surveys suggest that the weakening and recovery of substrate strength occurs relatively rapidly, that is, within around 1–10 years following the main shock, as inferred from changes in seismic velocity (e.g., Brenguier et al, ; Gassenmeier et al, ). We also acknowledge that earthquakes may affect landscape erodibility (Vanmaercke et al, ) and nonlandsliding erosional flux, but we expect a minor influence given the dominant role of landslides in sustaining long‐term erosional flux in steep mountains (Hovius et al, ; Keefer, ; Li et al, ; Marc et al, ). Overall, we expect that these factors contribute a minor part to the total earthquake‐caused erosional budget compared to coseismic landslides, but we recognize that they are also important mechanisms by which earthquakes may affect erosion.…”

Section: Model Summary Approximations and Simplificationsmentioning

confidence: 96%

“…The input parameters are T e , fault dip θ , normalized landslide failure susceptibility δ sn , mean rupture depth R 0 , landscape gradient, and landslide spatial decay factor β . We choose the ranges of the input parameters as observed in real geological settings ( R 0 : 2–40 km, T e : 2–40 km, log 10 δ sn : −1~1, θ : 10–70°, S mod : 20–40°, 1/ β : 0–5; Li et al, ; Marc, Hovius, Meunier, Gorum, et al, ; Meunier et al, ; Watts, ). For a series of earthquake magnitudes from M w = 6 to M w = 9 and different seismological landslide‐triggering factors that give different groups of M h , e 5 , e 6 , and e 7 , we fix all parameters at their medians, vary one parameter by 10% of the full sampling range at a time, and calculate the corresponding percentage deviation of V ls , V up seismic , Ω, and V up isostasy / V ls .…”

Section: Model Setup and Parameterizationmentioning

confidence: 99%

“…Postseismic relaxation also distributes coseismic uplift and subsidence to the far field. Thus, we expect erosion to be focused near range‐bounding faults (Li et al, ), while uplift and subsidence extend over wide areas. This pattern of concentrated erosion and distributed uplift and subsidence is consistent with the structure of a range‐basin system where erosion is focused along mountain fronts and uplift and subsidence are distributed broadly, demonstrating that earthquakes can produce such tectonic features.…”

Section: Postseismic Processes and Wavelengths Of Deformationsmentioning

confidence: 99%

“…These studies have been able to describe how first‐order topographic forms can emerge from repeated earthquake sequences, but they lacked quantitative constraints on earthquake‐triggered erosion. This gap can be filled by recent understanding of the earthquake balance problem (Hovius et al, ; Li et al, ; Marc, Hovius, & Meunier, ; Parker et al, ), informed by models describing landslide volumes (Marc, Hovius, Meunier, Gorum, et al, ) and observations that landslides are a dominant contributor to orogenic erosion (Keefer, ; Li et al, ; Malamud et al, ). Using this foundation to constrain the erosional term in models akin to that developed by King et al () promises a holistic, seismologically based description of topographic growth associated with seismic activity and affords the opportunity for a more complete consideration of the volume balance problem over full earthquake cycles.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Competing Effects of Mountain Uplift and Landslide Erosion Over Earthquake Cycles

West

Qiu

2019

JGR Solid Earth

Self Cite

View full text Add to dashboard Cite

Large earthquakes can construct mountainous topography by inducing rock uplift but also erode mountains by causing landslides. Observations following the 2008 Wenchuan earthquake show that landslide volumes in some cases match seismically induced uplift, raising questions about how the actions of individual earthquakes accumulate to build topography. Here we model the two-dimensional surface displacement field generated over a full earthquake cycle accounting for coseismic deformation, postseismic relaxation, landslide erosion, and erosion-induced isostatic compensation. We explore the related volume balance across different seismotectonic and topographic conditions and revisit the Wenchuan case in this context. The ratio (Ω) between landslide erosion and uplift is most sensitive to parameters determining landslide volumes (particularly earthquake magnitude M w , seismic energy source depth, and failure susceptibility, as well as the seismological factor responsible for triggering landslides), and is moderately sensitive to the effective elastic thickness of lithosphere, T e . For a specified magnitude, more erosive events (higher Ω) tend to occur at shallower depth, in thicker-T e lithosphere, and in steeper, more landslide-prone landscapes. For given landscape and seismotectonic conditions, the volumes of both landslides and uplift to first order positively scale with M w and seismic moment M o . However, higher M w earthquakes generate lower landslide and uplift volumes per unit M o , suggesting lower efficiency in the use of seismic energy to drive topographic change. With our model, we calculate the long-term average seismic volume balance for the eastern Tibetan region and find that the net topographic effect of earthquakes in this region tends to be constructive rather than erosive. Overall, destructive events are rare when considering processes over the full earthquake cycle, although they are more likely if only considering the coseismic volume budget (as was the case for the 2008 Wenchuan earthquake where landsliding substantially offset coseismic uplift). Irrespective of the net budget, our results suggest that the erosive power of earthquakes plays an important role in mountain belt evolution, including by influencing structures and spatial patterns of deformation, for example affecting the wavelength of topography.

show abstract