scholarly journals Time‐Invariant Late Quaternary Slip Rates Along the Agua Blanca Fault, Northern Baja California, Mexico

Tectonics ◽  
2020 ◽  
Vol 39 (9) ◽  
Author(s):  
P. O. Gold ◽  
W. M. Behr ◽  
J. M. Fletcher ◽  
T. K. Rockwell ◽  
P. M. Figueiredo
Keyword(s):  
Baja California ◽  
Late Quaternary ◽  
Slip Rates ◽  
Agua Blanca Fault ◽  
Time Invariant

scholarly journals Late Quaternary slip-rates along the Moxi and Zheduotang segments of the SE Xianshuihe fault, eastern Tibet, and geodynamic implications

2021 ◽  
Author(s):  
Marie-Luce Chevalier ◽  
mingkun bai ◽  
Shiguang Wang ◽  
Jiawei Pan ◽  
Philippe Hervé Leloup ◽  
...  
Keyword(s):  
Late Quaternary ◽  
Slip Rates ◽  
Eastern Tibet

A study of microseismicity in Northern Baja California, Mexico

1976 ◽  
Vol 66 (6) ◽  
pp. 1921-1929 ◽  
Author(s):  
Tracy L. Johnson ◽  
Juan Madrid ◽  
Theodore Koczynski
Keyword(s):  
Fault Zone ◽  
Focal Mechanism ◽  
Baja California ◽  
Surface Deformation ◽  
Normal Faults ◽  
East Side ◽  
Composite Focal Mechanism ◽  
Agua Blanca Fault ◽  
Eastern Edge ◽  
Low Activity

abstract Five microearthquake instruments were operated for 2 months in 1974 in a small mobile array deployed at various sites near the Agua Blanca and San Miguel faults. An 80-km-long dection of the San Miguel fault zone is presently active seismically, producing the vast majority of recorded earthquakes. Very low activity was recorded on the Agua Blanca fault. Events were also located near normal faults forming the eastern edge of the Sierra Juarez suggesting that these faults are active. Hypocenters on the San Miguel fault range in depth from 0 to 20 km although two-thirds are in the upper 10 km. A composite focal mechanism showing a mixture of right-lateral and dip slip, east side up, is similar to a solution obtained for the 1956 San Miguel earthquake which proved consistent with observed surface deformation.

scholarly journals A physics-based approach of deep interseismic creep for viscoelastic strike-slip earthquake cycle models

2019 ◽  
Vol 220 (1) ◽  
pp. 79-95
Author(s):  
Lucile Bruhat
Keyword(s):  
Surface Deformation ◽  
Slip Rate ◽  
Strike Slip ◽  
Dynamic Rupture ◽  
Crust And Upper Mantle ◽  
Slip Rates ◽  
Region I ◽  
Best Fitting ◽  
Time Invariant ◽  
Analytical Expressions

SUMMARY Most geodetic inversions of surface deformation rates consider the depth distribution of interseismic fault slip-rate to be time invariant. However, some numerical simulations show downdip penetration of dynamic rupture into regions with velocity-strengthening friction, with subsequent updip propagation of the locked-to-creeping transition. Recently, Bruhat and Segall developed a new method to characterize interseismic slip rates, that allows slip to penetrate up dip into the locked region. This simple model considered deep interseismic slip as a crack loaded at its downdip end, and provided analytical expressions for stress drop within the crack, slip and slip rate along the fault. This study extends this approach to strike-slip fault environments, and includes coupling of creep to viscoelastic flow in the lower crust and upper mantle. I use this model to investigate interseismic deformation rates along the Carrizo Plain section of the San Andreas fault. This study reviews possible models, elastic and viscoelastic, for fitting horizontal surface rates. Using this updated approach, I develop a physics-based solution for deep interseismic creep which accounts for possible slow vertical propagation, and investigate how it improves the fit of the horizontal deformation rates in the Carrizo Plain region. I found solutions for fitting the surface deformation rates that allow for reasonable estimates for earthquake rupture depth and coseismic displacement and improves the overall fit to the data. Best-fitting solutions present half-space relaxation time around 70 yr, and very low propagation speeds, less than a metre per year, suggesting a lack of creep propagation.

scholarly journals Late Quaternary eruption of the Ranau Caldera and new geological slip rates of the Sumatran Fault Zone in Southern Sumatra, Indonesia

2017 ◽  
Vol 4 (1) ◽  
Author(s):  
Danny Hilman Natawidjaja ◽  
Kyle Bradley ◽  
Mudrik R. Daryono ◽  
Sonny Aribowo ◽  
Jason Herrin
Keyword(s):  
Fault Zone ◽  
Late Quaternary ◽  
Slip Rates ◽  
Sumatran Fault

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.

scholarly journals Quantifying rates of “rifting while drifting” in the southern Gulf of California: The role of the southern Baja California microplate and its eastern boundary zone

Lithosphere ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 122-132
Author(s):  
Paul J. Umhoefer ◽  
C. Plattner ◽  
R. Malservisi
Keyword(s):  
Relative Motion ◽  
Gulf Of California ◽  
Baja California ◽  
Late Quaternary ◽  
Plate Boundary ◽  
Seafloor Spreading ◽  
Gravitational Potential Energy ◽  
Boundary Zone ◽  
Eastern Boundary ◽  
Topographic Relief

Abstract The southern Baja California (Mexico) microplate has been rapidly moving away from the North America plate since ca. 12 Ma. This relative motion toward the northwest developed an oblique-divergent plate boundary that formed the Gulf of California. The rift-drift hypothesis postulates that when a continent ruptures and seafloor spreading commences, rifting on the plate margins ceases, and the margins start to drift, subside, and accumulate postrift sediments, eventually becoming a passive margin. In contrast to this hypothesis, the southern part of the Baja California microplate (BCM), and in particular its actively deforming eastern boundary zone, has continued significant rifting for millions of years after seafloor spreading initiated within the southern Gulf of California at 6–2.5 Ma. This is a process we call “rifting-while-drifting.” Global positioning system (GPS)–based data collected from 1998 to 2011 show relative motion across the eastern boundary zone up to ∼2–3.2 mm/yr with respect to a stable BCM. Furthermore, the velocity directions are compatible with normal faulting across the eastern boundary zone nearly perpendicular to the trend of the plate boundary at the latitude of La Paz and therefore a highly strain partitioned domain. North of 25°N latitude up to the Loreto area, there is a domain with no strain partitioning, and northwest-directed transtensional deformation dominates. From long-term geologic and paleoseismology studies, late Quaternary faulting rates are equal to or less than the GPS-derived rates, while geologic rates older than 1–2 Ma are commonly much higher. We suggest that the “rifting-while-drifting” process may be caused by the large topographic relief across the BCM margin, which created a significant gradient in gravitational potential energy that helps in driving continued relatively slow faulting. The relief was inherited from the much faster faulting of the BCM eastern boundary zone before plate motions largely localized along the modern transform–spreading centers in the axis of the Gulf of California. The low sediment flux from the small drainages and arid climate on the southern Baja California Peninsula result in the maintenance of underfilled to starved basins, and the relatively slow late Quaternary active faulting promotes continued topographic relief over millions of years.

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