scholarly journals Adjoint slip inversion under a constrained optimization framework: revisiting the 2006 guerrero slow slip event

2021 ◽  
Author(s):  
J Tago ◽  
V M Cruz-Atienza ◽  
C Villafuerte ◽  
T Nishimura ◽  
V Kostoglodov ◽  
...  
Keyword(s):  
Model Space ◽  
Seismogenic Zone ◽  
Inversion Method ◽  
Seismic Gap ◽  
Slow Slip ◽  
Inversion Algorithm ◽  
Plate Interface ◽  
Tectonic Plates ◽  
Slow Slip Event ◽  
Slip Event

Summary To shed light on the prevalently slow, aseismic slip interaction between tectonic plates, we developed a new static slip inversion strategy, the ELADIN (ELastostatic ADjoint INversion) method, that uses the adjoint elastostatic equations to compute the gradient of the cost function. ELADIN is a 2-step inversion algorithm to efficiently handle plausible slip constraints. First it finds the slip that best explains the data without any constraint, and then refines the solution by imposing the constraints through a Gradient Projection Method. To obtain a selfsimilar, physically-consistent slip distribution that accounts for sparsity and uncertainty in the data, ELADIN reduces the model space by using a von Karman regularization function that controls the wavenumber content of the solution, and weights the observations according to their covariance using the data precision matrix. Since crustal deformation is the result of different concomitant interactions at the plate interface, ELADIN simultaneously determines the regions of the interface subject to both stressing (i.e., coupling) and relaxing slip regimes. For estimating the resolution, we introduce a mobile checkerboard analysis that allows to determine lower-bound fault resolution zones for an expected slip-patch size and a given stations array. We systematically test ELADIN with synthetic inversions along the whole Mexican subduction zone and use it to invert the 2006 Guerrero Slow Slip Event (SSE), which is one of the most studied SSEs in Mexico. Since only 12 GPS stations recorded the event, careful regularization is thus required to achieve reliable solutions. We compared our preferred slip solution with two previously published models and found that our solution retains their most reliable features. In addition, although all three SSE models predict an upward slip penetration invading the seismogenic zone of the Guerrero seismic gap, our resolution analysis indicates that this penetration might not be a reliable feature of the 2006 SSE.

scholarly journals Slow slip on the northern Hikurangi subduction interface, New Zealand

2021 ◽  
Author(s):  
A Douglas ◽  
J Beavan ◽  
L Wallace ◽  
John Townend
Keyword(s):  
New Zealand ◽  
Surface Displacement ◽  
Seismogenic Zone ◽  
Gps Data ◽  
Slow Slip ◽  
Slow Slip Event ◽  
Slip Event ◽  
American Geophysical ◽  
Continuous Gps ◽  
American Geophysical Union

In October 2002, a surface displacement episode of 20-30 mm magnitude was observed over a ∼10 day period on two continuous Global Positioning System (GPS) instruments near Gisborne, North Island, New Zealand. We interpret this to result from slow slip on the northern Hikurangi subduction interface. Using ten years of regional campaign GPS (1995-2004) and recent continuous GPS data, we estimate the recurrence interval for similar events to be 2-3 yrs. In November 2004, a similar slow slip event occurred within this recurrence period. The 2002 event can be modeled by ∼18 cm of slow slip near the down-dip end of the seismogenic zone on the subduction interface offshore of Gisborne. The campaign GPS data show that the 2002 slow slip event had little effect on regional strain patterns. Copyright 2005 by the American Geophysical Union.

scholarly journals Shallow slow earthquakes to decipher future catastrophic earthquakes in the Guerrero seismic gap.

2020 ◽  
Author(s):  
Raymundo Plata-Martínez ◽  
Satoshi Ide ◽  
Masanao Shinohara ◽  
Emmanuel Soliman Garcia Mortel ◽  
Naoto Mizuno ◽  
...  
Keyword(s):  
Seismogenic Zone ◽  
Seismic Gap ◽  
Slow Slip ◽  
Dynamic Rupture ◽  
Plate Interface ◽  
Slow Slip Events ◽  
Repeating Earthquakes ◽  
Slow Earthquakes ◽  
Slip Area ◽  
Large Earthquakes

Abstract The Guerrero seismic gap is presumed to be a major source of seismic and tsunami hazard along the Mexican subduction zone. Until recently, there were limited observations to describe the shallow portion of the plate interface in Guerrero. For this reason, we deployed offshore instrumentation to gain new seismic data and identify the extent of the seismogenic zone inside the Guerrero gap. We discovered episodic shallow tremors and potential slow slip events which, together with repeating earthquakes, seismicity, residual gravity and residual bathymetry suggest that a portion of the shallow plate interface in the Guerrero seismic gap undergoes stable slip. This mechanical condition may not only explain the long return period of large earthquakes with origins inside the Guerrero seismic gap, but also reveal why the rupture from past M<8 earthquakes on adjacent megathrust fault segments did not propagate into the gap to encompass a larger slip area. Nevertheless, a large enough earthquake initiating nearby could rupture through the entire Guerrero seismic gap if driven by dynamic rupture effects.

scholarly journals Shallow slow earthquakes to decipher future catastrophic earthquakes in the Guerrero seismic gap

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
R. Plata-Martinez ◽  
S. Ide ◽  
M. Shinohara ◽  
E. S. Garcia ◽  
N. Mizuno ◽  
...  
Keyword(s):  
Seismogenic Zone ◽  
Seismic Gap ◽  
Slow Slip ◽  
Dynamic Rupture ◽  
Plate Interface ◽  
Slow Slip Events ◽  
Repeating Earthquakes ◽  
Residual Gravity ◽  
Slow Earthquakes ◽  
Large Earthquakes

AbstractThe Guerrero seismic gap is presumed to be a major source of seismic and tsunami hazard along the Mexican subduction zone. Until recently, there were limited observations at the shallow portion of the plate interface offshore Guerrero, so we deployed instruments there to better characterize the extent of the seismogenic zone. Here we report the discovery of episodic shallow tremors and potential slow slip events in Guerrero offshore. Their distribution, together with that of repeating earthquakes, seismicity, residual gravity and bathymetry, suggest that a portion of the shallow plate interface in the gap undergoes stable slip. This mechanical condition may not only explain the long return period of large earthquakes inside the gap, but also reveals why the rupture from past M < 8 earthquakes on adjacent megathrust segments did not propagate into the gap to result in much larger events. However, dynamic rupture effects could drive one of these nearby earthquakes to break through the entire Guerrero seismic gap.

scholarly journals Slow slip on the northern Hikurangi subduction interface, New Zealand

2021 ◽  
Author(s):  
A Douglas ◽  
J Beavan ◽  
L Wallace ◽  
John Townend
Keyword(s):  
New Zealand ◽  
Surface Displacement ◽  
Seismogenic Zone ◽  
Gps Data ◽  
Slow Slip ◽  
Slow Slip Event ◽  
Slip Event ◽  
American Geophysical ◽  
Continuous Gps ◽  
American Geophysical Union

In October 2002, a surface displacement episode of 20-30 mm magnitude was observed over a ∼10 day period on two continuous Global Positioning System (GPS) instruments near Gisborne, North Island, New Zealand. We interpret this to result from slow slip on the northern Hikurangi subduction interface. Using ten years of regional campaign GPS (1995-2004) and recent continuous GPS data, we estimate the recurrence interval for similar events to be 2-3 yrs. In November 2004, a similar slow slip event occurred within this recurrence period. The 2002 event can be modeled by ∼18 cm of slow slip near the down-dip end of the seismogenic zone on the subduction interface offshore of Gisborne. The campaign GPS data show that the 2002 slow slip event had little effect on regional strain patterns. Copyright 2005 by the American Geophysical Union.

scholarly journals Adjoint Slip Inversion under a Constrained Optimization Framework: Revisiting the 2006 Guerrero Slow Slip Event

2020 ◽  
Author(s):  
Josué Tago ◽  
Víctor M. Cruz-Atienza ◽  
Carlos Villafuerte ◽  
Takuya Nishimura ◽  
Vladimir Kostoglodov ◽  
...  
Keyword(s):  
Constrained Optimization ◽  
Slow Slip ◽  
Slow Slip Event ◽  
Optimization Framework ◽  
Slip Event

Observing seismic signatures of slow slip events with unsupervised learning

2021 ◽  
Author(s):  
Leonard Seydoux ◽  
Michel Campillo ◽  
René Steinmann ◽  
Randall Balestriero ◽  
Maarten de Hoop
Keyword(s):  
Clustering Algorithm ◽  
Low Frequency ◽  
Seismic Signal ◽  
Geodetic Data ◽  
Slow Slip ◽  
Slow Slip Events ◽  
Slow Slip Event ◽  
Intermittent Behavior ◽  
Slow Earthquakes ◽  
Slip Event

&lt;p&gt;Slow slip events are observed in geodetic data, and are occasionally associated with seismic signatures such as slow earthquakes (low-frequency earthquakes, tectonic tremors). In particular, it was shown that swarms of slow earthquake can correlate with slow slip events occurrence, and allowed to reveal the intermittent behavior of several slow slip events. This observation was possible thanks to detailed analysis of slow earthquakes catalogs and continuous geodetic data, but in every case, was limited to particular classes of seismic signatures. In the present study, we propose to infer the classes of seismic signals that best correlate with the observed geodetic data, including the slow slip event. We use a scattering network (a neural network with wavelet filters) in order to find meaningful signal features, and apply a hierarchical clustering algorithm in order to infer classes of seismic signal. We then apply a regression algorithm in order to predict the geodetic data, including slow slip events, from the occurrence of inferred seismic classes. This allow to (1) identify seismic signatures associated with the slow slip events as well as (2) infer the the contribution of each classes to the overall displacement observed in the geodetic data. We illustrate our strategy by revisiting the slow-slip event of 2006 that occurred beneath Guerrero, Mexico.&lt;/p&gt;

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