scholarly journals Intermittent tremor migrations beneath Guerrero, Mexico, and implications for fault healing within the slow slip zone

2017 ◽  
Vol 44 (2) ◽  
pp. 760-770 ◽  
Author(s):  
Yajun Peng ◽  
Allan M. Rubin
Keyword(s):  
Slip Zone ◽  
Slow Slip ◽  
Fault Healing

Fault healing plays a key role in creating the spectrum of tectonic faulting styles from seismic to aseismic slip

2020 ◽  
Author(s):  
Chris Marone
Keyword(s):  
Potential Energy ◽  
Stress Drop ◽  
Elastic Strain ◽  
Stability Boundary ◽  
Fault Slip ◽  
Slow Slip ◽  
Stick Slip ◽  
Slow Earthquakes ◽  
The Stability ◽  
Fault Healing

<p>Tectonic faults fail in a broad spectrum of modes ranging from aseismic creep to fast, ordinary, earthquakes modulated by elastodynamic rupture processes. Laboratory friction experiments with repetitive stick-slip failure have reproduced this complete range of modes with failure durations spanning several orders of magnitude. These works show that the frictional weakening rate with slip (i.e., the rheological critical stiffness <em>k<sub>c</sub> =σ<sub>n</sub>(b-a)/D<sub>c</sub></em>, where <em>σ<sub>n</sub></em> is effective fault normal stress, <em>D<sub>c</sub></em> is the friction critical slip distance and <em>(b-a)</em> represents the friction rate parameter) is the primary control on the mode of slip, but higher-order effects are also important including variation of <em>k<sub>c</sub>  </em>with slip velocity.  Far from the stability boundary, stick-slip occurs when the rate of elastic unloading with slip <em>k</em> is small compared to the frictional weakening rate (i.e., <em>k</em><<<em>k<sub>c</sub></em>). Potential energy, in the form of stored elastic strain, drives rapid fault acceleration. Near the stability boundary, when <em>k ~ k<sub>c</sub></em>, lab experiments document slow and quasi-dynamic failure events, consistent with the observation that earthquake stress drop is negligible for slow earthquakes. Lab data show that stick-slip stress drop decreases systematically as <em>k/k<sub>c</sub></em> approaches 1 from below. There are two possible scenarios for slow slip near the stability boundary, although they are degenerate in most cases. 1) Fault slip relieves elastic stresses prior to failure and thus the potential energy needed to drive fast rupture is absent. 2) Elastic strain accumulates but the fault rheology is velocity strengthening or otherwise inconsistent with rapid slip, for example because the frictional weakening rate <em>k<sub>c</sub></em>  is low.  In Scenario 1, slip can occur early in the seismic cycle, as creep, or later in the cycle when shear stress reaches a critical value for precursory slip.  In either case, slip occurs because the rate of fault healing is low compared to the stressing rate. A low rate of fault healing can also explain Scenario 2 because the friction state evolution parameter <em>b</em> scales directly with the rate of fault healing and <em>k<sub>c</sub></em>. Given that the friction parameter <em>a</em> is positive definite, the frictional healing rate (<em>b</em>) sets the scale of <em>k<sub>c</sub></em> for a given value of <em>D<sub>c</sub></em>. Thus, while these two scenarios for slow slip appear distinct they both derive from the rate of fault healing.  Exceptions would involve faults that are strongly velocity weakening <em>(b-a)</em> >>0 yet have negligible healing rates (<em>b</em> ~ 0), which is indeed rare.  The rate of fault healing is expected to vary with mineralogy, effective stress, temperature and other factors. Thus, while we expect a systematic variation of seismic style with depth, associated with changes in <em>k<sub>c</sub></em>, we should not be surprised to find a spectrum of faulting styles throughout the lithosphere, including a range of styles at a given location.  Discoveries of seismic tremor, low frequency earthquakes, and other modes of fault slip are challenging our views of tectonic faulting and they highlight the need for close connections between field observations, detailed laboratory work and theoretical studies of friction and faulting.</p>

scholarly journals Long-lived shallow slow-slip events on the Sunda megathrust

2021 ◽  
Author(s):  
Rishav Mallick ◽  
Aron J. Meltzner ◽  
Louisa L. H. Tsang ◽  
Eric O. Lindsey ◽  
Lujia Feng ◽  
...  
Keyword(s):  
Slow Slip ◽  
Slow Slip Events

scholarly journals Configuration and structure of the Philippine Sea Plate off Boso, Japan: constraints on the shallow subduction kinematics, seismicity, and slow slip events

2019 ◽  
Vol 71 (1) ◽  
Author(s):  
Aki Ito ◽  
Takashi Tonegawa ◽  
Naoki Uchida ◽  
Yojiro Yamamoto ◽  
Daisuke Suetsugu ◽  
...  
Keyword(s):  
Receiver Function ◽  
Function Analysis ◽  
Philippine Sea Plate ◽  
Slow Slip ◽  
Low Velocity ◽  
Slow Slip Events ◽  
Philippine Sea ◽  
Receiver Function Analysis ◽  
Eastern Edge ◽  
Upper Boundary

Abstract We applied tomographic inversion and receiver function analysis to seismic data from ocean-bottom seismometers and land-based stations to understand the structure and its relationship with slow slip events off Boso, Japan. First, we delineated the upper boundary of the Philippine Sea Plate based on both the velocity structure and the locations of the low-angle thrust-faulting earthquakes. The upper boundary of the Philippine Sea Plate is distorted upward by a few kilometers between 140.5 and 141.0°E. We also determined the eastern edge of the Philippine Sea Plate based on the delineated upper boundary and the results of the receiver function analysis. The eastern edge has a northwest–southeast trend between the triple junction and 141.6°E, which changes to a north–south trend north of 34.7°N. The change in the subduction direction at 1–3 Ma might have resulted in the inflection of the eastern edge of the subducted Philippine Sea Plate. Second, we compared the subduction zone structure and hypocenter locations and the area of the Boso slow slip events. Most of the low-angle thrust-faulting earthquakes identified in this study occurred outside the areas of recurrent Boso slow slip events, which indicates that the slow slip area and regular low-angle thrust earthquakes are spatially separated in the offshore area. In addition, the slow slip areas are located only at the contact zone between the crustal parts of the North American Plate and the subducting Philippine Sea Plate. The localization of the slow slip events in the crust–crust contact zone off Boso is examined for the first time in this study. Finally, we detected a relatively low-velocity region in the mantle of the Philippine Sea Plate. The low-velocity mantle can be interpreted as serpentinized peridotite, which is also found in the Philippine Sea Plate prior to subduction. The serpentinized peridotite zone remains after the subduction of the Philippine Sea Plate and is likely distributed over a wide area along the subducted slab.

scholarly journals In Situ Shear Test for Revealing the Mechanical Properties of the Gravelly Slip Zone Soil

Sensors ◽  
2020 ◽  
Vol 20 (22) ◽  
pp. 6531 ◽  
Author(s):  
Zongxing Zou ◽  
Qi Zhang ◽  
Chengren Xiong ◽  
Huiming Tang ◽  
Lei Fan ◽  
...  
Keyword(s):  
Mechanical Property ◽  
Plastic Deformation ◽  
Shear Test ◽  
Slip Zone ◽  
Three Gorges Reservoir Area ◽  
Silty Clay ◽  
Sigmoid Function ◽  
In Situ Test ◽  
Deformation Stage

Slip zone soil is usually composed of clay or silty clay; in some special geological environments, it contains gravels, which make the properties of the slip zone soil more complex. Unfortunately, in many indoor shear tests, gravels are removed to meet the demands of apparatus size, and the in situ mechanical property of the gravelly slip zone soil is rarely studied. In this study, the shear mechanical property of the gravelly slip zone soil of Huangtupo landslide in the Three Gorges Reservoir area of China was investigated by the in situ shear test. The test results show that the shear deformation process of the gravelly slip zone soil includes an elastic deformation stage, elastic–plastic deformation stage, and plastic deformation stage. Four functions were introduced to express the shear constitutive model of the gravelly slip zone soil, and the asymmetric sigmoid function was demonstrated to be the optimum one to describe the relationship of the shear stress and shear displacement with a correlation coefficient of 0.986. The comparison between the in situ test and indoor direct shear test indicates that gravels increase the strength of the slip zone soil. Therefore, the shear strength parameters of the gravelly slip zone soil obtained by the in situ test are more preferable for evaluating the stability of the landslide and designing the anti-slide structures.

Carbonization of Carbonates and Fractionation of Stable Carbon Isotopes in a Dynamic Slip Zone

2020 ◽  
Vol 58 (9) ◽  
pp. 981-993
Author(s):  
Yu. A. Morozov ◽  
V. S. Sevastianov ◽  
A. Yu. Yurchenko ◽  
O. V. Kuznetsova
Keyword(s):  
Carbon Isotopes ◽  
Stable Carbon Isotopes ◽  
Slip Zone ◽  
Stable Carbon ◽  
Dynamic Slip

Estimation of frictional properties and slip evolution on a long-term slow slip event fault with the ensemble Kalman filter: numerical experiments

2019 ◽  
Vol 219 (3) ◽  
pp. 2074-2096 ◽  
Author(s):  
Kazuro Hirahara ◽  
Kento Nishikiori
Keyword(s):  
Surface Displacement ◽  
Slip Rate ◽  
Slow Slip ◽  
Slow Slip Events ◽  
Actual Distribution ◽  
Frictional Properties ◽  
Data Analyses ◽  
Bungo Channel ◽  
Megathrust Faults ◽  
Gnss Data

Summary A variety of slow slip events at subduction zones have been observed. They can be stress meters for monitoring the stress state of megathrust faults during their earthquake cycles. In this study, we focus on long-term slow slip events (LSSEs) recurring at downdip portions of megathrust faults among such slow earthquakes. Data analyses and simulation studies of LSSEs have so far been executed independently. In atmosphere and ocean sciences, data assimilations that optimally combine data analyses and simulation studies have been developed. We develop a method for estimating frictional properties and monitoring slip evolution on an LSSE fault, with a sequential data assimilation method, the ensemble Kalman filter (EnKF). We executed numerical twin experiments for the Bungo Channel LSSE fault in southwest Japan to validate the method. First, based on a rate- and state-dependent friction law, we set a rate-weakening circular LSSE patch on the rate-strengthening flat plate interface, whose critical nucleation size is larger than that of the patch, and reproduced the observed Bungo Channel LSSEs with recurrence times of approximately 7 yr and slip durations of 1 yr. Then, we synthesized the observed data of surface displacement rates at uniformly distributed stations with noises from the simulated slip model. Using our EnKF method, we successfully estimated the frictional parameters and the slip rate evolution after a few cycles. Secondly, we considered the effect of the megathrust fault existing in the updip portion of the LSSE fault, as revealed by kinematic inversion studies of Global Navigation Satellite System (GNSS) data and added this locked region with a slip deficit rate in the model. We estimated the slip rate on the locked region only kinematically, but the quasi-dynamic equation of motion in each LSSE fault cell includes the stress term arising from the locked region. Based on this model, we synthesized the observed surface displacement rate data for the actual distribution of GNSS stations and executed EnKF estimations including the slip rate on the locked region. The slip rate on the locked region could be quickly retrieved. Even for the actual distribution of GNSS stations, we could successfully estimate frictional parameters and slip evolution on the LSSE fault. Thus, our twin numerical experiments showed the validity of our EnKF method, although we need further studies for actual GNSS data analyses.

scholarly journals Segmentation of Slow Slip Events in South Central Alaska Possibly Controlled by a Subducted Oceanic Plateau

2018 ◽  
Vol 123 (1) ◽  
pp. 418-436 ◽  
Author(s):  
Haotian Li ◽  
Meng Wei ◽  
Duo Li ◽  
Yajing Liu ◽  
YoungHee Kim ◽  
...  
Keyword(s):  
Slow Slip ◽  
Slow Slip Events ◽  
Oceanic Plateau ◽  
South Central

scholarly journals COEXISTENCE OF FAST AND SLOW SLIP EVENTS IN LABORATORY SEISMIC CYCLES

2020 ◽  
Author(s):  
Kseniya G. Morozova ◽  
Vadim K. Markov ◽  
Dmitry V. Pavlov ◽  
Maxim F. Popov ◽  
Alexey A. Ostapchuk
Keyword(s):  
Slow Slip ◽  
Slow Slip Events ◽  
Seismic Cycles
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