scholarly journals The impact of earthquake cycle variability on neotectonic and paleoseismic slip rate estimates

2018 ◽  
Author(s):  
Richard Styron
Keyword(s):  
Late Quaternary ◽  
Slip Rate ◽  
Earthquake Recurrence ◽  
Coseismic Slip ◽  
Slip Rates ◽  
Rate Study ◽  
Recurrence Intervals ◽  
Short Time ◽  
Fault Displacement ◽  
The Impact

Abstract. Because of the natural variability (aleatoric uncertainty) in earthquake recurrence intervals and coseismic displacements on a fault, cumulative slip on a fault does not increase linearly or perfectly step-wise with time; instead, some amount of variability in shorter-term slip rates results. Though this variability could greatly affect the accuracy of neotectonic (i.e., late Quaternary) and paleoseismic slip rate estimates, these effects have not been quantified. In this study, idealized faults with four different, representative earthquake recurrence distributions are created with equal mean recurrence intervals (1,000 years) and coseismic slip distributions, and the variability in slip rate measurements over 500 to 100,000 year measurement windows is calculated for all faults through Monte Carlo simulations. The recurrence distributions used are quasi-periodic, unclustered and clustered lognormal distributions, and an unclustered exponential distribution. The results demonstrate that the most important parameter is the coefficient of variation (COV = standard deviation/mean) of the recurrence distributions rather than the shape of the distribution itself. Slip rate variability over short time scales ( 5 mean earthquake cycles (as in a neotectonic slip rate study). These uncertainties are independent of, and should be propagated with uncertainties in fault displacement and geochronologic measurements used to estimate slip rates. They may then aid in the comparison of slip rates from different methods or the evaluation of potential slip rate changes over time.

scholarly journals The impact of earthquake cycle variability on neotectonic and paleoseismic slip rate estimates

Solid Earth ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 15-25 ◽  
Author(s):  
Richard Styron
Keyword(s):  
Late Quaternary ◽  
Epistemic Uncertainty ◽  
Slip Rate ◽  
Earthquake Recurrence ◽  
Coseismic Slip ◽  
Slip Rates ◽  
True Value ◽  
Recurrence Intervals ◽  
The Impact ◽  
Earthquake Cycles

Abstract. Because of the natural (aleatoric) variability in earthquake recurrence intervals and coseismic displacements on a fault, cumulative slip on a fault does not increase linearly or perfectly step-wise with time; instead, some amount of variability in shorter-term slip rates results. Though this variability could greatly affect the accuracy of neotectonic (i.e., late Quaternary) and paleoseismic slip rate estimates, these effects have not been quantified. In this study, idealized faults with four different, representative, earthquake recurrence distributions are created with equal mean recurrence intervals (1000 years) and coseismic slip distributions, and the variability in slip rate estimates over 500- to 100 000-year measurement windows is calculated for all faults through Monte Carlo simulations. Slip rates are calculated as net offset divided by elapsed time, as in a typical neotectonic study. The recurrence distributions used are quasi-periodic, unclustered and clustered lognormal distributions, and an unclustered exponential distribution. The results demonstrate that the most important parameter is the coefficient of variation (CV = standard deviation ∕ mean) of the recurrence distributions rather than the shape of the distribution itself. Slip rate variability over short timescales (< 5000 years or 5 mean earthquake cycles) is quite high, varying by a factor of 3 or more from the mean, but decreases with time and is close to stable after ∼40 000 years (40 mean earthquake cycles). This variability is higher for recurrence distributions with a higher CV. The natural variability in the slip rate estimates compared to the true value is then used to estimate the epistemic uncertainty in a single slip rate measurement (as one would make in a geological study) in the absence of any measurement uncertainty. This epistemic uncertainty is very high (a factor of 2 or more) for measurement windows of a few mean earthquake cycles (as in a paleoseismic slip rate estimate), but decreases rapidly to a factor of 1–2 with > 5 mean earthquake cycles (as in a neotectonic slip rate study). These uncertainties are independent of, and should be propagated with, uncertainties in fault displacement and geochronologic measurements used to estimate slip rates. They may then aid in the comparison of slip rates from different methods or the evaluation of potential slip rate changes over time.

Complex Slip Distribution of the 2021 Mw 7.4 Maduo, China, Earthquake: An Event Occurring on the Slowly Slipping Fault

2021 ◽  
Author(s):  
Rumeng Guo ◽  
Hongfeng Yang ◽  
Yu Li ◽  
Yong Zheng ◽  
Lupeng Zhang
Keyword(s):  
Slip Rate ◽  
Slip Distribution ◽  
Seismic Gap ◽  
Seismogenic Fault ◽  
Coseismic Slip ◽  
Slip Rates ◽  
Kunlun Mountain ◽  
Coulomb Failure ◽  
Main Fault ◽  
Large Earthquakes

Abstract The 21 May 2021 Maduo earthquake occurred on the Kunlun Mountain Pass–Jiangcuo fault (KMPJF), a seismogenic fault with no documented large earthquakes. To probe its kinematics, we first estimate the slip rates of the KMPJF and Tuosuo Lake segment (TLS, ∼75 km north of the KMPJF) of the East Kunlun fault (EKLF) based on the secular Global Positioning System (GPS) data using the Markov chain Monte Carlo method. Our model reveals that the slip rates of the KMPJF and TLS are 1.7 ± 0.8 and 7.1 ± 0.3 mm/yr, respectively. Then, we invert high-resolution GPS and Interferometric Synthetic Aperture Radar observations to decipher the fault geometry and detailed coseismic slip distribution associated with the Maduo earthquake. The geometry of the KMPFJ significantly varies along strike, composed of five fault subsegments. The most slip is accommodated by two steeply dipping fault segments, with the patch of large sinistral slip concentrated in the shallow depth on a simple straight structure. The released seismic moment is ∼1.5×1020  N·m, equivalent to an Mw 7.39 event, with a peak slip of ∼9.3 m. Combining the average coseismic slip and slip rate of the main fault, an earthquake recurrence period of ∼1250−400+1120  yr is estimated. The Maduo earthquake reminds us to reevaluate the potential of seismic gaps where slip rates are low. Based on our calculated Coulomb failure stress, the Maduo earthquake imposes positive stress on the Maqin–Maqu segment of the EKLF, a long-recognized seismic gap, implying that it may accelerate the occurrence of the next major event in this region.

Bounds on the Average Recurrence Interval of Major Earthquakes Along the Haiyuan Fault In North-Central China

1988 ◽  
Vol 59 (3) ◽  
pp. 81-89 ◽  
Author(s):  
Zhang Peizhen ◽  
Peter Molnar ◽  
Zhang Weigi ◽  
Deng Qidong ◽  
Wang Yipeng ◽  
...  
Keyword(s):  
Slip Rate ◽  
Recurrence Interval ◽  
Central China ◽  
Great Earthquake ◽  
Average Amount ◽  
Earthquake Recurrence ◽  
Surface Rupture ◽  
North Central ◽  
Recurrence Intervals ◽  
Historic Record

Abstract Evidence of surface rupture has been found in trenches near Caiyuan and Shaomayin along the Haiyuan fault, where a great earthquake occurred in 1920. In addition to the 1920 earthquake, faulting occurred at least once between 2590 ± 190 years and 1525 ± 170 years B.P. in Caiyuan, and there probably was another event since 1525 ± 170 years B.P. The formation and later tilting of fault-related, scarp-derived colluvial wedges in the Shaomayin trench appear to record the occurrence of two pre-1920 events in the last 2200–3700 years, but there could have been three or more events. The average recurrence interval for great earthquakes along the Haiyuan fault probably exceeds 700 years, for the 1920 Haiyuan earthquake is the only major event to have been reported in this area in as many years of recorded history. Using a Holocene slip rate along this fault of 8 ± 2 mm/yr, and 8 m as the average amount of offset associated with past great events that have been determined by our previous studies, the resultant earthquake recurrence intervals would be from 800 to 1400 years. The results from our trenches and the historic record are consistent with this range.

scholarly journals A systems-based approach to parameterise seismic hazard in regions with little historical or instrumental seismicity: The South Malawi Active Fault Database

2020 ◽  
Author(s):  
Jack N. Williams ◽  
Hassan Mdala ◽  
Åke Fagereng ◽  
Luke N. J. Wedmore ◽  
Juliet Biggs ◽  
...  
Keyword(s):  
Seismic Hazard ◽  
Active Fault ◽  
Slip Rate ◽  
Fault Slip ◽  
Slip Rates ◽  
Scaling Relationships ◽  
Regional Strain ◽  
Earthquake Scaling ◽  
Recurrence Intervals ◽  
Fault Slip Rate

Abstract. Seismic hazard is frequently characterised using instrumental seismic records. However, in regions where the instrumental record is short relative to earthquake repeat times, extrapolating it to estimate seismic hazard can misrepresent the probable location, magnitude, and frequency of future large earthquakes. Although paleoseismology can address this challenge, this approach requires certain geomorphic settings and carries large inherent uncertainties. Here, we outline how fault slip rates and recurrence intervals can be estimated through an approach that combines fault geometry, earthquake-scaling relationships, geodetically derived regional strain rates, and geological constraints of regional strain distribution. We then apply this approach to the southern Malawi Rift where, although no on-fault slip rate measurements exist, there are theoretical and observational constraints on how strain is distributed between border and intrabasinal faults. This has led to the development of the South Malawi Active Fault Database (SMAFD), the first database of its kind in the East African Rift System (EARS) and designed so that the outputs can be easily incorporated into Probabilistic Seismic Hazard Analysis. We estimate earthquake magnitudes of MW 5.4–7.2 for individual fault sections in the SMAFD, and MW 6.0–7.8 for whole fault ruptures. These potentially high magnitudes for continental normal faults reflect southern Malawi's 11–140 km long faults and thick (30–35 km) seismogenic crust. However, low slip rates (intermediate estimates 0.05–0.8 mm/yr) imply long recurrence intervals between events: 102–105 years for border faults and 103–106 years for intrabasinal faults. Sensitivity analysis indicates that the large range of these estimates can be reduced most significantly from an improved understanding of the rate and partitioning of rift-extension in southern Malawi, earthquake scaling relationships, and earthquake rupture scenarios. Hence these are critical areas for future research. The SMAFD provides a framework for using geological and geodetic information to characterize seismic hazard in low strain rate settings with few on-fault slip rate measurements, and could be adapted for use elsewhere in the EARS or globally.

scholarly journals Effects of Erosion and Deposition on Constraining Vertical Slip Rates of Thrust Faults: A Case Study of the Minle–Damaying Fault in the North Qilian Shan, NE Tibetan Plateau

2021 ◽  
Vol 9 ◽  
Author(s):  
Qingri Liu ◽  
Huiping Zhang ◽  
Youli Li ◽  
Feipeng Huang ◽  
Xudong Zhao ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Slip Rate ◽  
Simulation Method ◽  
The Tibetan Plateau ◽  
Stratigraphic Sequence ◽  
Erosion And Deposition ◽  
Slip Rates ◽  
The North ◽  
Vertical Fault ◽  
Fault Displacement

The height of a thrust-fault scarp on a fluvial terrace would be modified due to erosion and deposition, and these surface processes can also influence the dating of terraces. Under such circumstances, the vertical slip rate of a fault can be misestimated due to the inaccurate displacement and/or abandonment age of the terrace. In this contribution, considering the effect of erosion and deposition on fault scarps, we re-constrained the vertical slip rate of the west end of the Minle–Damaying Fault (MDF), one of the thrusts in the north margin of the Qilian Shan that marks the northeastern edge of the Tibetan Plateau. In addition, we tried to explore a more reliable method for obtaining the vertical fault displacement and the abandonment age of terraces with AMS 14C dating. The heights of the surface scarps and the displacements of the fluvial gravel layers exposed on the Yudai River terraces were precisely measured with the Structure from Motion (SfM) photogrammetry and the real-time kinematic (RTK) GPS. The Monte Carlo simulation method was used to estimate the uncertainties of fault displacements and vertical slip rates. Based on comparative analysis, the dating sample from the fluvial sand layer underlying the thickest loess in the footwall was suggested to best represent the abandonment age of the terrace, and the fluvial gravel layer could better preserve the original vertical fault displacement compared with the surface layer. Using the most reliable ages and vertical offsets, the vertical slip rate of the MDF was estimated to be 0.25–0.28 mm/a since 42.3 ± 0.5 ka (T10) and 0.14–0.24 mm/a since 16.1 ± 0.2 ka (T7). The difference between the wrong vertical slip rate and the right one can even reach an order of magnitude. We also suggest that if the built measuring profile is long enough, the uncertainties in the height of a surface scarp would be better constrained and the result can also be taken as the vertical fault displacement. Furthermore, the consistency of chronology with stratigraphic sequence or with terrace sequence are also key to constraining the abandonment ages of terraces. The fault activity at the study site is weaker than that in the middle and east segments of the MDF, which is likely due to its end position.

Estimating the probability of occurrences of surface faulting earthquakes on the Wasatch fault zone, Utah

1980 ◽  
Vol 70 (5) ◽  
pp. 1463-1478
Author(s):  
Lloyd S. Cluff ◽  
Ashok S. Patwardhan ◽  
Kevin J. Coppersmith
Keyword(s):  
Fault Zone ◽  
Late Quaternary ◽  
Probabilistic Approach ◽  
Historical Seismicity ◽  
Generation Process ◽  
Large Magnitude ◽  
Earthquake Recurrence ◽  
Slip Rates ◽  
Geological Information ◽  
Wasatch Fault

abstract Although geological and geomorphic evidence strongly suggests that the Wasatch fault zone has generated large-magnitude earthquakes in late Quaternary time, the fault zone has not been associated with earthquakes greater than magnitude 512 in the past 133 yr. Therefore, realistic estimates of the likelihood of future damaging earthquakes must be based on more than historical seismicity data. The data base can be expanded by collecting site-specific geological information on earthquake recurrence and fault slip rates and by using this information in a model of the earthquake generation process. Uncertainties in both the physical basis for the model and in the geological parameters dictate a probabilistic approach. A semi-Markov model provides real-time probabilities of occurrence of at least one moderate to large (magnitude 612 or larger) earthquake at either of two sites for given elapsed times. Probabilities derived for the entire Wasatch fault zone are based on earthquake recurrence data on individual fault segments and are especially sensitive to elapsed times on individual segments.

scholarly journals OSL dating of the late Quaternary slip rate on the Gyaring co Fault in central Tibet

2016 ◽  
Vol 43 (1) ◽  
pp. 162-173 ◽  
Author(s):  
Duo Wang ◽  
Gong-Ming Yin ◽  
Xu-Long Wang ◽  
Chun-Ru Liu ◽  
Fei Han ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Late Quaternary ◽  
Slip Rate ◽  
Strike Slip ◽  
Alluvial Fan ◽  
Osl Dating ◽  
The Tibetan Plateau ◽  
Slip Rates ◽  
Absolute Age ◽  
Central Tibet

Abstract The Gyaring Co Fault (GCF) is an active right-lateral strike-slip fault in central Tibet that accommodates convergence between India and Asia in the interior of the Tibetan Plateau. The average long-term slip rate of the fault remains controversial, given the absence of absolute age data of faulted geomorphic features. We have applied optically stimulated luminescence (OSL) dating to the northern segment of the GCF, revealing that the GCF has displaced alluvial fans at Aerqingsang by 500 ± 100 m since their deposition at ~109 ka, yielding a slip rate of 4.6 ± 1.0 mm/yr. A slip rate of 3.4 ± 0.4 mm/yr is inferred from analysis of an alluvial fan with an offset of 65 ± 5 m (~19 ka) at Quba site 1. The Holocene slip rate is estimated to be 1.9 ± 0.3 mm/yr, as inferred from the basal age (~8.3 ka) of terrace T1 that has a gully displacement of 16 ± 2 m at Quba site 2. These slip rates are generally lower early estimates (10–20 mm/yr), but are consistent with more recent results (2.2–4.5 mm/yr) and GPS data for other strike-slip faults in this region, indicating that deformation may be distributed across the entire Tibetan Plateau. Moreover, we suggest that the slip rate along the GCF may have decreased slightly during the late Quaternary.

scholarly journals Geologic and geodetic constraints on the seismic hazard of Malawi’s active faults: The Malawi Seismogenic Source Database (MSSD)

2021 ◽  
Author(s):  
Jack N. Williams ◽  
Luke N. J. Wedmore ◽  
Åke Fagereng ◽  
Maximilian J. Werner ◽  
Hassan Mdala ◽  
...  
Keyword(s):  
Seismic Hazard ◽  
Active Fault ◽  
Active Faults ◽  
Slip Rate ◽  
Slip Rates ◽  
Source Database ◽  
Seismogenic Sources ◽  
Seismogenic Source ◽  
Recurrence Intervals ◽  
Seismic Reflector

Abstract. Active fault data are commonly used in seismic hazard assessments, but there are challenges in deriving the slip rate, geometry, and frequency of earthquakes along active faults. Herein, we present the open-access geospatial Malawi Seismogenic Source Database (MSSD), which describes the seismogenic properties of faults that have formed during East African rifting in Malawi. We first use empirical observations to geometrically classify active faults into section, fault, and multi-fault seismogenic sources. For sources in the North Basin of Lake Malawi, slip rates can be derived from the vertical offset of a seismic reflector that is estimated to be 75 ka based on dated core. Elsewhere, slip rates are constrained from advancing a ‘systems-based’ approach that partitions geodetically-derived rift extension rates in Malawi between seismogenic sources using a priori constraints on regional strain distribution in magma-poor continental rifts. Slip rates are then combined with source geometry and empirical scaling relationships to estimate earthquake magnitudes and recurrence intervals, and their uncertainty is described from the variability of outcomes from a logic tree used in these calculations. We find that for sources in the Lake Malawi’s North Basin, where slip rates can be derived from both the geodetic data and the offset seismic reflector, the slip rate estimates are within error of each other, although those from the offset reflector are higher. Sources in the MSSD are 5–200 km long, which implies that large magnitude (MW 7–8) earthquakes may occur in Malawi. Low slip rates (0.05–2 mm/yr), however, mean that the frequency of such events will be low (recurrence intervals ~103–104 years). The MSSD represents an important resource for investigating Malawi’s increasing seismic risks and provides a framework for incorporating active fault data into seismic hazard assessment in other tectonically active regions.

scholarly journals Constraining Central Washington’s Potential Seismic Hazard

Eos ◽  
2018 ◽  
Vol 99 ◽  
Author(s):  
Terri Cook
Keyword(s):  
Seismic Hazard ◽  
Slip Rate ◽  
Fault Geometry ◽  
Earthquake Recurrence ◽  
Recurrence Intervals

Fault geometry and slip rate analyses show deformation in the Yakima Fold Province accelerated in the Pleistocene and has remained elevated, offering new insights into earthquake recurrence intervals.

New constraints on Quaternary slip partitioning near the eastern termination of the Altyn Tagh Fault 

2021 ◽  
Author(s):  
Nimrod Wieler ◽  
Amit Mushkin ◽  
Eitan Shelef ◽  
Huiping Zhang ◽  
Amir Sagy ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Late Quaternary ◽  
Slip Rate ◽  
Alluvial Fan ◽  
Luminescence Dating ◽  
The Tibetan Plateau ◽  
Altyn Tagh Fault ◽  
Slip Rates ◽  
Altyn Tagh ◽  
Slip Partitioning

&lt;p&gt;Slip partitioning along the northern boundary of the Tibetan Plateau is essential for understanding regional deformation and the seismic potential of the different faults that accommodate it. Within this framework the Altyn Tagh Fault (ATF) is commonly viewed as the primary structure that separates the Tibetan Plateau from the stable Gobi-Alashan block to the north. Late Quaternary sinistral slip rates of 8-12 mm/yr across the central ATF between 86&amp;#176; and 93&amp;#176;E decrease eastwards to zero as the fault approaches its mid-continental termination at ~97&amp;#176;E. To better understand how late Quaternary slip is partitioned along the ATF&amp;#8217;s eastern termination we obtained new slip-rate measurements&amp;#160; for the ~200-km-long left-lateral ENE striking Sanweishan Fault (SSF) located ~60 km north of the ATF between 94&amp;#176;-96&amp;#176;E near the town of Dunhuang.&lt;/p&gt;&lt;p&gt;Multiple sinistral offsets ranging up to 600 m were identified by linking the clast assemblage of offset alluvial fan remnants with their provenance upstream of the fault. &amp;#160;Luminescence dating revealed depositional ages ranging from 100 - 200 ka for the offset features and time-invariant minimum sinistral slip of 2.5&amp;#177;1 mm/yr during the last ~200 ka, which is approximately an order of magnitude higher than previously reported slip-rates for the SSF. Our results indicate that the SSF and the eastern segment of the ATF accommodate comparable magnitudes of late Quaternary slip. Considering this substantial transfer of lateral slip as far as 60 km north of the eastern ATF we propose that the SSF may represent juvenile northeastward expansion of the Tibetan Plateau into previously stable parts of the Gobi-Alashan block.&lt;/p&gt;

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