scholarly journals Slow slip events in the roots of the San Andreas fault

2019 ◽  
Vol 5 (2) ◽  
pp. eaav3274 ◽  
Author(s):  
Baptiste Rousset ◽  
Roland Bürgmann ◽  
Michel Campillo
Keyword(s):  
Global Positioning System ◽  
San Andreas Fault ◽  
Slow Slip ◽  
Slow Slip Events ◽  
San Andreas ◽  
Global Positioning ◽  
The Moment ◽  
Episodic Tremor ◽  
Seismic Signature

Episodic tremor and accompanying slow slip are observed at the down-dip edge of subduction seismogenic zones. While tremors are the seismic signature of this phenomenon, they correspond to a small fraction of the moment released; thus, the associated fault slip can be quantified only by geodetic observations. On continental strike-slip faults, tremors have been observed in the roots of the Parkfield segment of the San Andreas fault. However, associated transient aseismic slip has never been detected. By making use of the timing of transient tremor activity and the dense Parkfield-area global positioning system network, we can detect deep slow slip events (SSEs) at 16-km depth on the Parkfield segment with an average moment equivalent toMw4.90 ± 0.08. Characterization of transient SSEs below the Parkfield locked asperity, at the transition with the creeping section of the San Andreas fault, provides new constraints on the seismic cycle in this region.

scholarly journals Connecting a broad spectrum of transient slip on the San Andreas fault

2020 ◽  
Vol 6 (33) ◽  
pp. eabb2489
Author(s):  
Yen Joe Tan ◽  
David Marsan
Keyword(s):  
Broad Spectrum ◽  
San Andreas Fault ◽  
Low Frequency ◽  
Small Deformation ◽  
Slow Slip ◽  
Rupture Velocity ◽  
Slow Slip Events ◽  
Temporal Decay ◽  
San Andreas ◽  
Aftershock Sequences

Strain accumulated on the deep extension of some faults is episodically released during transient slow-slip events, which can subsequently load the shallow seismogenic region. At the San Andreas fault, the characteristics of slow-slip events are difficult to constrain geodetically due to their small deformation signal. Slow-slip events (SSEs) are often accompanied by coincident tremor bursts composed of many low-frequency earthquakes. Here, we probabilistically estimate the spatiotemporal clustering properties of low-frequency earthquakes detected along the central San Andreas fault. We find that tremor bursts follow a power-law spatial and temporal decay similar to earthquake aftershock sequences. The low-frequency earthquake clusters reveal that the underlying slow-slip events have two modes of rupture velocity. Compared to regular earthquakes, these slow-slip events have smaller stress drop and rupture velocity but follow similar magnitude-frequency, moment-area, and moment-duration scaling. Our results connect a broad spectrum of transient fault slip that spans several orders of magnitude in rupture velocity.

scholarly journals Estimating Vehicle Movement Direction from Smartphone Accelerometers Using Deep Neural Networks

Sensors ◽  
2018 ◽  
Vol 18 (8) ◽  
pp. 2624 ◽  
Author(s):  
Sara Hernández Sánchez ◽  
Rubén Fernández Pozo ◽  
Luis Hernández Gómez
Keyword(s):  
Global Positioning System ◽  
Driving Forces ◽  
Movement Direction ◽  
Motion Sensors ◽  
Forward Movement ◽  
Significant Acceleration ◽  
Global Positioning ◽  
Vehicle Movement

Characterization of driving maneuvers or driving styles through motion sensors has become a field of great interest. Before now, this characterization used to be carried out with signals coming from extra equipment installed inside the vehicle, such as On-Board Diagnostic (OBD) devices or sensors in pedals. Nowadays, with the evolution and scope of smartphones, these have become the devices for recording mobile signals in many driving characterization applications. Normally multiple available sensors are used, such as accelerometers, gyroscopes, magnetometers or the Global Positioning System (GPS). However, using sensors such as GPS increase significantly battery consumption and, additionally, many current phones do not include gyroscopes. Therefore, we propose the characterization of driving style through only the use of smartphone accelerometers. We propose a deep neural network (DNN) architecture that combines convolutional and recurrent networks to estimate the vehicle movement direction (VMD), which is the forward movement directional vector captured in a phone’s coordinates. Once VMD is obtained, multiple applications such as characterizing driving styles or detecting dangerous events can be developed. In the development of the proposed DNN architecture, two different methods are compared. The first one is based on the detection and classification of significant acceleration driving forces, while the second one relies on longitudinal and transversal signals derived from the raw accelerometers. The final success rate of VMD estimation for the best method is of 90.07%.

scholarly journals Distant Quake Triggered Slow Slip on Southern San Andreas

Eos ◽  
2019 ◽  
Vol 100 ◽  
Author(s):  
Terri Cook
Keyword(s):  
High Resolution ◽  
San Andreas Fault ◽  
Slow Slip ◽  
San Andreas ◽  
Surface Displacements ◽  
High Resolution Map ◽  
Resolution Map

A high-resolution map of surface displacements indicates that the 2017 Chiapas earthquake caused substantial creep along a segment of the San Andreas Fault, located 3,000 kilometers away.

scholarly journals A preliminary catalogue of Hikurangi, New Zealand, Slow Slip Earthquakes, from January 2000 to February 2014

2021 ◽  
Author(s):  
◽  
B. Peter Baxter
Keyword(s):  
New Zealand ◽  
Temporal Evolution ◽  
Processing Route ◽  
Slow Slip ◽  
Slow Slip Events ◽  
Slip Rates ◽  
The North ◽  
General Terms ◽  
Significant Step

<p>This thesis documents processing carried out on cGPS data from 115 sites in the North Island and the top of the South Island of New Zealand in order to produce a catalogue of slow slip events (SSEs) for the Hikurangi Margin covering the period Jan 2000 to Feb 2014. It covers the background to the concept of SSEs and the reporting to date on their occurrence along the Margin, the methods used in the processing and analysis, the results of each significant step, and discussion of the results.  It has been shown that the processing route adopted in this work has reduced the average noise levels in the cGPS data by up to 67%, and has eliminated virtually all correlated (“pink”) noise, thus enabling the detection of small-amplitude events (~ 2mm in cGPS signals).  One hundred and fifty events are catalogued in total, of which 137 are considered likely to be SSEs or similar. The catalogue includes estimates of the uncertainty in each parameter and is thus considered the most comprehensive to date. Sixteen of the inversion results were able to be directly compared with published information and showed satisfactory agreement on location and equivalent moment magnitudes.  The important aspects of the project that have been developed further than has been documented to date in the literature include: partitioning of the secular velocity field over the margin to allow the underlying tectonic signal to be better understood; detailed characterization of the temporal evolution of the SSEs; the identification of approximately 40 events that show slips in the opposite direction to that expected; and some preliminary conclusions concerning event scaling.  One of the objectives of the project was to identify whether there were fundamental differences in the characteristics of SSEs in the northeast and southwest of the margin. On the basis of the analyses to date, it appears that the events form a continuum, at least in terms of depth, temporal evolution, source slip rates and scaling, but in general terms the events in the southwest have been confirmed to be of longer duration than those in the northeast.  The project has identified further work that needs to be carried out or is ongoing in order to maximize the value of these new results.</p>

scholarly journals Detection of Deep Low-frequency Earthquakes in the Nankai Subduction Zoneover 11 Years Usingamatched Filter Technique

2020 ◽  
Author(s):  
Aitaro Kato ◽  
Shigeki Nakagawa
Keyword(s):  
Matched Filter ◽  
Low Frequency ◽  
Slow Slip ◽  
Slow Slip Events ◽  
Filter Technique ◽  
Strike Direction ◽  
Episodic Tremor And Slip ◽  
Spatio Temporal ◽  
Episodic Tremor

Abstract To improve our understanding of the long-term behavior of low-frequency earthquakes (LFEs) along the tremor belt of the Nankai subduction zone, we applied a matched filter technique to continuous seismic data recorded by a dense and highly sensitive seismic network over an 11year window, April 2004 to August 2015. We detected a total of ~510,000 LFEs, or ~23× the number of LFEs in the JMA catalog for the same period. During long-term slow slip events (SSEs) in the Bungo Channel, a series of migrating LFEbursts intermittently occurred along the fault-strike direction, with slow hypocenter propagation. Elastic energy released by long-term SSEs appears to control the extent of LFE activity. We identify slowlymigrating fronts of LFEs during major episodic tremor and slip (ETS)events, which extend over distances of up to 100 km and follow diffusion-like patterns of spatial evolution with a diffusion coefficient of ~104 m2/s. This migration pattern closely matches the spatio-temporal evolution of tectonictremors reported by previous studies. At shorter distances, up to 15 km, we discovered rapid diffusion-like migrationof LFEs with a coefficient of ~105 m2/s. We also recognize that rapid migration of LFEs occurred intermittently in many streaks during major ETS episodes. These observations suggest that slow slip transients contain a multitude of smaller, temporally clustered fault slip events whose evolution is controlled by a diffusional process.

scholarly journals Daily measurement of slow slip from low-frequency earthquakes is consistent with ordinary earthquake scaling

2019 ◽  
Vol 5 (10) ◽  
pp. eaaw9386 ◽  
Author(s):  
William B. Frank ◽  
Emily E. Brodsky
Keyword(s):  
Full Range ◽  
Low Frequency ◽  
Blind Spot ◽  
Earthquake Activity ◽  
Slow Slip ◽  
Earthquake Cycle ◽  
Slow Slip Events ◽  
Event Time ◽  
Earthquake Scaling ◽  
The Moment

Slow slip transients on faults can last from seconds to months and stitch together the earthquake cycle. However, no single geophysical instrument is able to observe the full range of slow slip because of bandwidth limitations. Here, we connect seismic and geodetic data from the Mexican subduction zone to explore an instrumental blind spot. We establish a calibration of the daily median amplitude of the seismically recorded low-frequency earthquakes to the daily geodetically recorded moment rate of previously established slow slip events. This calibration allows us to use the precise evolution of low-frequency earthquake activity to quantitatively measure the moment of smaller, subdaily slip events that are unresolvable by geodesy alone. The resulting inferred slow slip moments scale with duration and inter-event time like ordinary earthquakes. These new quantifications help connect slow and fast events in a broad spectrum of transient slip and suggest that slow slip events behave much like ordinary earthquakes.

scholarly journals Slow Slip Event On the Southern San Andreas Fault Triggered by the 2017 M w 8.2 Chiapas (Mexico) Earthquake

2019 ◽  
Vol 124 (9) ◽  
pp. 9956-9975 ◽  
Author(s):  
Ekaterina Tymofyeyeva ◽  
Yuri Fialko ◽  
Junle Jiang ◽  
Xiaohua Xu ◽  
David Sandwell ◽  
...  
Keyword(s):  
San Andreas Fault ◽  
Slow Slip ◽  
Slow Slip Event ◽  
San Andreas ◽  
Slip Event ◽  
Mexico Earthquake
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