Horizontal strain-rates and throw-rates across breached relay zones, central Italy: Implications for the preservation of throw deficits at points of normal fault linkage

Walker, Joanna Faure; Roberts, Gerald; Cowie, P. A.; Papanikolaou, Ioannis; Sammonds, Peter; Michetti, Alessandro Maria; Phillips, R. J.

doi:10.1016/j.jsg.2009.06.011

Cited by 59 publications

(54 citation statements)

References 41 publications

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“…These data were extended and reanalyzed by Schlagenhauf et al [2010], who accounted for several additional influences on the 36 Cl production rate. The results of their study imply that samples near the top of the ∼7 m high (∼10 m along plane) smooth and well‐preserved portion of the basal scarp (as opposed to the degraded upper portions [ Faure Walker et al , 2009]) have been exposed for about 7.2 ka, supporting the widely held view that these scarps are postglacial features. They also concluded that the well‐preserved portion of the scarp reflects a minimum of five earthquakes.…”

Section: Field Setting and Fault Scarp Observationsmentioning

confidence: 76%

“…A stronger test will require a fault with an unusually well‐characterized late Quaternary slip‐rate profile, combined with high‐resolution topographic data. One important caveat is that the hillslope angle is not set by the slip rate directly, but rather by the rate of exhumation of the fault plane, which can be influenced by net erosion or deposition in the hanging wall [ Whittaker et al , 2007] as well as by the dip and strike of the fault plane [ Faure Walker et al , 2009]. For that reason it is important to identify locations where the footwall has been relatively stable over the time period of interest, and to document carefully the local fault plane geometry.…”

Section: Discussionmentioning

confidence: 99%

“…The gray shading around the regression line (Figure 7) encompasses the sum of errors due the uncertainty in measured pit depth (±1 cm) and the uncertainty in the age of each band of the scarp (±0.5 ka). Note that older ages [e.g., Faure Walker et al , 2009] would reduce both the Holocene scarp erosion rate and the inferred longer‐term erosion rate, and therefore would not change the relative difference between them.…”

Section: Methodsmentioning

confidence: 99%

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Geomorphic significance of postglacial bedrock scarps on normal-fault footwalls

et al. 2011

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[1] The existence of well-preserved Holocene bedrock fault scarps along active normal faults in the Mediterranean region and elsewhere suggests a dramatic reduction in rates of rock weathering and erosion that correlates with the transition from glacial to interglacial climate. We test and quantify this interpretation using a case study in the Italian Central Apennines. Holocene rates are derived from measurements of weathering-pit depth along the Magnola scarp, where previous cosmogenic 36 Cl analyses constrain exposure history. To estimate the average hillslope erosion rate over ∼10 5 years, we introduce a simple geometric model of normal-fault footwall slope evolution. The model predicts that the gradient of a weathering-limited footwall hillslope is set by fault dip angle and the ratio of slip rate to erosion rate; if either slip or erosion rate is known, the other can be derived. Applying this model to the Magnola fault yields an estimated average weathering rate on the order of 0.2-0.4 mm/yr, more than 10 times higher than either the Holocene scarp weathering rate or modern regional limestone weathering rates. A numerical model of footwall growth and erosion, in which erosion rate tracks the oxygen-isotope curve, reproduces the main features of hillslope and scarp morphology and suggests that the hillslope erosion rate has varied by about a factor of 30 over the past one to two glacial cycles. We conclude that preservation of carbonate fault scarps reflects strong climatic control on rock breakdown by frost cracking.

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Section: Field Setting and Fault Scarp Observationsmentioning

confidence: 76%

Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Geomorphic significance of postglacial bedrock scarps on normal-fault footwalls

et al. 2011

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“…The asymmetry in boulder trails populations may, perhaps, be related to this. A speculative interpretation might be that slip‐distributions for each of the individual marsquake ruptures that produced these boulder‐trail anomalies were skewed toward the tips of fault segments, so that the largest coseismic displacements, and hence highest levels of ground acceleration, were located close to the en echelon step‐over between the fault segments, as occurs on the Earth (Faure Walker et al, ).…”

Section: Discussionmentioning

confidence: 99%

Possible Evidence for Variation in Magnitude for Marsquakes From Fallen Boulder Populations, Grjota Valles, Mars

Brown

Roberts

2019

JGR Planets

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Following observations of mobilized boulder trail populations from Cerberus Fossae, Mars, that have been interpreted as possible evidence of large‐magnitude marsquakes rupturing for distances of ~207 km along exposed active faults, additional boulder trail populations were measured along shorter faults within the region of Grjota Valles (50‐ to 150‐km length) to test the hypotheses that (1) these faults are also candidate locations for marsquakes and (2) that marsquake magnitude might be smaller, limited by fault dimensions available for rupture. For a region containing two en echelon graben, boulder trail data define two anomalies with maxima in (a) boulder trails per kilometer and (b) maximum width of boulder trails, one that is ~116 km in length along strike and the other ~70 km in length along strike. Values for the maxima are 45 trails per kilometer and 5‐m mean trail width for the 70‐km‐long anomaly and 115 trails per kilometer with 5.3‐m mean trail width for the 116‐km‐long anomaly, above background values measured elsewhere along these faults of zero trails per kilometer with zero boulder trail widths. If combined with published data from Cerberus Fossae with an ~207‐km‐long anomaly in boulder trails per km (125 trails per kilometer maxima) and maximum mean boulder trail width (8.5‐m maximum trail width), the three data sets suggest correlations between the (a) along‐strike length of boulder trail anomalies, (b) boulder trails per kilometer, and (c) maximum boulder trail width. If interpreted as due to single marsquakes, and if the dimensions of these anomalies are a proxy for rupture length, when combined, one interpretation of this is that boulders have been mobilized by marsquakes and that the marsquake magnitude is proportional to the along‐strike length of the anomalies. In other words, the data suggest that marsquake magnitude, if that is the cause of the anomalies, is limited by fault length as expected for terrestrial seismically active faults. Such findings suggest that the Martian surface may have been shaken, in the very recent past, by large‐magnitude marsquakes. We discuss this in terms of the seismicity of Mars.

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“…Spatially transient temporal clusters of seismicity in the region over 10 2 –10 3 years (Figure ) [ Schlagenhauf et al , ; Benedetti et al , ; Tesson et al , ], and shorter‐term clusters of earthquakes (e.g., the 2016 central Italy earthquake sequence) suggest that faults are interacting over a range of timescales. Furthermore, the region has exceptional constraints on (i) the long record of historical earthquakes (Figure ) which appears to be complete for events M > 5.8 since 1349 A.D. [ Guidoboni et al , ], (ii) the constraints on the mechanism controlling fault slip rates over multiple seismic cycles where slip rates appear to be controlled by viscous deformation at depth in response to long wavelength topographic uplift [ Faure Walker et al , ; Cowie et al , ], (iii) the extensive record of Holocene fault slip rates in the region where nearly every fault has a slip rate derived from offset geomorphic features dating from 15 ± 3 ka (Figure a) [e.g., Roberts and Michetti , ; Faure Walker et al , ], and (iv) the extensive record of fault geometries and kinematics across faults in the region (Figure b) [ Roberts and Michetti , ; Faure Walker et al , , ]. We use these constraints and records of earthquake activity in the central Apennines to model interseismic and coseismic stress interactions to explore the characteristics of an actively interacting distributed fault network and to determine whether Coulomb stress changes can explain observations of transient fault slip rates and irregular earthquake recurrence intervals.…”

Section: Introductionmentioning

confidence: 99%

A 667 year record of coseismic and interseismic Coulomb stress changes in central Italy reveals the role of fault interaction in controlling irregular earthquake recurrence intervals

et al. 2017

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Current studies of fault interaction lack sufficiently long earthquake records and measurements of fault slip rates over multiple seismic cycles to fully investigate the effects of interseismic loading and coseismic stress changes on the surrounding fault network. We model elastic interactions between 97 faults from 30 earthquakes since 1349 A.D. in central Italy to investigate the relative importance of co‐seismic stress changes versus interseismic stress accumulation for earthquake occurrence and fault interaction. This region has an exceptionally long, 667 year record of historical earthquakes and detailed constraints on the locations and slip rates of its active normal faults. Of 21 earthquakes since 1654, 20 events occurred on faults where combined coseismic and interseismic loading stresses were positive even though ~20% of all faults are in “stress shadows” at any one time. Furthermore, the Coulomb stress on the faults that experience earthquakes is statistically different from a random sequence of earthquakes in the region. We show how coseismic Coulomb stress changes can alter earthquake interevent times by ~103 years, and fault length controls the intensity of this effect. Static Coulomb stress changes cause greater interevent perturbations on shorter faults in areas characterized by lower strain (or slip) rates. The exceptional duration and number of earthquakes we model enable us to demonstrate the importance of combining long earthquake records with detailed knowledge of fault geometries, slip rates, and kinematics to understand the impact of stress changes in complex networks of active faults.

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Horizontal strain-rates and throw-rates across breached relay zones, central Italy: Implications for the preservation of throw deficits at points of normal fault linkage

Cited by 59 publications

References 41 publications

Geomorphic significance of postglacial bedrock scarps on normal-fault footwalls

Geomorphic significance of postglacial bedrock scarps on normal-fault footwalls

Possible Evidence for Variation in Magnitude for Marsquakes From Fallen Boulder Populations, Grjota Valles, Mars

A 667 year record of coseismic and interseismic Coulomb stress changes in central Italy reveals the role of fault interaction in controlling irregular earthquake recurrence intervals

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