scholarly journals Seismicity and shallow slab geometry in the central Vanuatu subduction zone

2015 ◽  
Vol 120 (8) ◽  
pp. 5606-5623 ◽  
Author(s):  
Christian Baillard ◽  
Wayne C. Crawford ◽  
Valérie Ballu ◽  
Marc Régnier ◽  
Bernard Pelletier ◽  
...  
Keyword(s):  
Subduction Zone ◽  
Slab Geometry

scholarly journals Seismic Imaging of the Alaska Subduction Zone: Implications for Slab Geometry and Volcanism

2018 ◽  
Vol 19 (11) ◽  
pp. 4541-4560 ◽  
Author(s):  
Robert Martin‐Short ◽  
Richard Allen ◽  
Ian D. Bastow ◽  
Robert W. Porritt ◽  
Meghan S. Miller
Keyword(s):  
Subduction Zone ◽  
Seismic Imaging ◽  
Slab Geometry

scholarly journals Along-strike variation in slab geometry at the southern Mariana subduction zone revealed by seismicity through ocean bottom seismic experiments

2019 ◽  
Vol 218 (3) ◽  
pp. 2122-2135 ◽  
Author(s):  
Gaohua Zhu ◽  
Hongfeng Yang ◽  
Jian Lin ◽  
Zhiyuan Zhou ◽  
Min Xu ◽  
...  
Keyword(s):  
High Resolution ◽  
Subduction Zone ◽  
Matched Filter ◽  
Near Field ◽  
Broad Band ◽  
Velocity Model ◽  
Ocean Bottom ◽  
Slab Geometry ◽  
Seismicity Distribution ◽  
Geodynamic Processes

SUMMARYWe have conducted the first passive Ocean Bottom Seismograph (OBS) experiment near the Challenger Deep at the southernmost Mariana subduction zone by deploying and recovering an array of 6 broad-band OBSs during December 2016–June 2017. The obtained passive-source seismic records provide the first-ever near-field seismic observations in the southernmost Mariana subduction zone. We first correct clock errors of the OBS recordings based on both teleseismic waveforms and ambient noise cross-correlation. We then perform matched filter earthquake detection using 53 template events in the catalogue of the US Geological Survey and find >7000 local earthquakes during the 6-month OBS deployment period. Results of the two independent approaches show that the maximum clock drifting was ∼2 s on one instrument (OBS PA01), while the rest of OBS waveforms had negligible time drifting. After timing correction, we locate the detected earthquakes using a newly refined local velocity model that was derived from a companion active source experiment in the same region. In total, 2004 earthquakes are located with relatively high resolution. Furthermore, we calibrate the magnitudes of the detected earthquakes by measuring the relative amplitudes to their nearest relocated templates on all OBSs and acquire a high-resolution local earthquake catalogue. The magnitudes of earthquakes in our new catalogue range from 1.1 to 5.6. The earthquakes span over the Southwest Mariana rift, the megathrust interface, forearc and outer-rise regions. While most earthquakes are shallow, depths of the slab earthquakes increase from ∼100 to ∼240 km from west to east towards Guam. We also delineate the subducting interface from seismicity distribution and find an increasing trend in dip angles from west to east. The observed along-strike variation in slab dip angles and its downdip extents provide new constraints on geodynamic processes of the southernmost Mariana subduction zone.

Geometric controls on megathrust earthquakes

2020 ◽  
Vol 222 (2) ◽  
pp. 1270-1282
Author(s):  
Steven M Plescia ◽  
Gavin P Hayes
Keyword(s):  
Subduction Zone ◽  
Subduction Zones ◽  
Earthquake Hazard ◽  
Earthquake Rupture ◽  
Primary Control ◽  
Slab Geometry ◽  
Megathrust Earthquakes ◽  
Maximum Earthquake Magnitude ◽  
Maximum Earthquake

SUMMARY The role of subduction zone geometry in the nucleation and propagation of great-sized earthquake ruptures is an important topic for earthquake hazard, since knowing how big an earthquake can be on a given fault is fundamentally important. Past studies have shown subducting bathymetric features (e.g. ridges, fracture zones, seamount chains) may arrest a propagating rupture. Other studies have correlated the occurrence of great-sized earthquakes with flat megathrusts and homogenous stresses over large distances. It remains unclear, however, how subduction zone geometry and the potential for great-sized earthquakes (M 8+) are quantifiably linked—or indeed whether they can be. Here, we examine the potential role of subduction zone geometry in limiting earthquake rupture by mapping the planarity of seismogenic zones in the Slab2 subduction zone geometry database. We build from the observation that historical great-sized earthquakes have preferentially occurred where the surrounding megathrust is broadly planar, and we use this relationship to search for geometrically similar features elsewhere in subduction zones worldwide. Assuming geometry exerts a primary control on earthquake propagation and termination, we estimate the potential size distribution of large (M 7+) earthquakes and the maximum earthquake magnitude along global subduction faults based on geometrical features alone. Our results suggest that most subduction zones are capable of hosting great-sized earthquakes over much of their area. Many bathymetric features previously identified as barriers are indistinguishable from the surrounding megathrust from the perspective of slab curvature, meaning that they either do not play an important role in arresting earthquake rupture or that their influence on slab geometry at depth is not resolvable at the spatial scale of our subduction zone geometry models.

scholarly journals Density structure and geometry of the Costa Rican subduction zone from 3-D gravity modeling and local earthquake data

Solid Earth ◽  
2015 ◽  
Vol 6 (4) ◽  
pp. 1169-1183 ◽  
Author(s):  
O. H. Lücke ◽  
I. G. Arroyo
Keyword(s):  
Costa Rica ◽  
Subduction Zone ◽  
Gravity Modeling ◽  
Northwestern Part ◽  
Intraplate Seismicity ◽  
Gradual Change ◽  
Slab Geometry ◽  
Local Networks ◽  
Volcanic Arc ◽  
Dehydration Reactions

Abstract. The eastern part of the oceanic Cocos Plate presents a heterogeneous crustal structure due to diverse origins and ages as well as plate-hot spot interactions which originated the Cocos Ridge, a structure that converges with the Caribbean Plate in southeastern Costa Rica. The complex structure of the oceanic plate directly influences the dynamics and geometry of the subduction zone along the Middle American Trench. In this paper an integrated interpretation of the slab geometry in Costa Rica is presented based on 3-D density modeling of combined satellite and surface gravity data, constrained by available geophysical and geological data and seismological information obtained from local networks. The results show the continuation of steep subduction geometry from the Nicaraguan margin into northwestern Costa Rica, followed by a moderate dipping slab under the Central Cordillera toward the end of the Central American Volcanic Arc. Contrary to commonly assumed, to the southeast end of the volcanic arc, our preferred model shows a steep, coherent slab that extends up to the landward projection of the Panama Fracture Zone. Overall, a gradual change in the depth of the intraplate seismicity is observed, reaching 220 km in the northwestern part, and becoming progressively shallower toward the southeast, where it reaches a maximum depth of 75 km. The changes in the terminal depth of the observed seismicity correlate with the increased density in the modeled slab. The absence of intermediate depth (> 75 km) intraplate seismicity in the southeastern section and the higher densities for the subducted slab in this area, support a model in which dehydration reactions in the subducted slab cease at a shallower depth, originating an anhydrous and thus aseismic slab.

scholarly journals Tectonic tremors in the Northern Mexican subduction zone remotely triggered by the 2017 Mw8.2 Tehuantepec earthquake

2021 ◽  
Vol 73 (1) ◽  
Author(s):  
Masatoshi Miyazawa ◽  
Miguel Ángel Santoyo
Keyword(s):  
Subduction Zone ◽  
Dynamic Strain ◽  
Plate Boundaries ◽  
Maximum Magnitude ◽  
Slab Geometry ◽  
Plate Interface ◽  
Wavefield Simulation ◽  
Stress Changes ◽  
Triggered Tremor ◽  
Mexican Subduction Zone

AbstractSurface waves from the 2017 Mw8.2 Tehuantepec earthquake remotely triggered tectonic tremors in the Jalisco region, approximately 1000 km WNW in the northern Mexican subduction zone. This is the first observation of tremor triggering in this region and one of the largest known examples of a triggered tremor in the world. Although prior studies have found tectonic tremors triggered by teleseismic waves in subduction zones and plate boundaries, further investigation of tremor triggering is crucially important for understanding the causative mechanism. We calculate the stress and strain changes across the three-dimensional plate interface attributable to seismic waves from the earthquake by full wavefield simulation. The maximum magnitude of the dynamic strain tensor eigenvalues on the plate interface, where tremors likely occur, is approximately 10–6. The subducting slab geometry effectively amplifies triggering waves. The triggering Coulomb failure stress changes resolved for a thrust fault plane consistent with the geometry are estimated to be approximately 10–40 kPa. The relationship between the triggering stress and triggered tremor amplitude may indicate that the aσ of the rate–state-dependent friction law is 10–100 kPa.

scholarly journals Incorporating teleseismic tomography data into models of upper mantle slab geometry

2018 ◽  
Vol 215 (1) ◽  
pp. 325-332 ◽  
Author(s):  
Daniel Evan Portner ◽  
Gavin P Hayes
Keyword(s):  
Subduction Zone ◽  
Upper Mantle ◽  
Seismic Velocity ◽  
Slab Model ◽  
Slab Geometry ◽  
Teleseismic Tomography ◽  
Subducting Slab ◽  
Tomography Data

SUMMARY Earthquake-based models of slab geometry are limited by the distribution of earthquakes within a subducting slab, which is often heterogeneous. The fast seismic velocity signature of slabs in tomography studies is independent of the distribution of earthquakes within the slab, providing a critical constraint on slab geometry when earthquakes are absent. In order to utilize this constraint, researchers typically hand-contour images of subducting slabs in tomography models, leading to a subjective final slab model. With this paper, we present an automated procedure for extracting slab geometry from teleseismic tomography volumes that limits this subjectivity and provides constraints on the structure of aseismic segments of slabs. This procedure is designed as a complement to earthquake-based slab models rather than as a replacement, which can help to broaden the extent of existing subduction zone geometry databases.

scholarly journals Tectonic Tremors in the Northern Mexican Subduction Zone Remotely Triggered by the 2017 Mw8.2 Tehuantepec Earthquake

2020 ◽  
Author(s):  
Masatoshi Miyazawa ◽  
Miguel Ángel Santoyo
Keyword(s):  
Subduction Zone ◽  
Dynamic Strain ◽  
Plate Boundaries ◽  
Maximum Magnitude ◽  
Slab Geometry ◽  
Plate Interface ◽  
Wavefield Simulation ◽  
Stress Changes ◽  
Triggered Tremor ◽  
Mexican Subduction Zone

Abstract Surface waves from the 2017 Mw8.2 Tehuantepec earthquake remotely triggered tectonic tremors in the Jalisco region, approximately 1000 km WNW in the northern Mexican subduction zone. This is the first observation of tremor triggering in this region and one of the largest known examples of a triggered tremor in the world. Although prior studies have found tectonic tremors triggered by teleseismic waves in subduction zones and plate boundaries, further investigation of tremor triggering is crucially important for understanding the causative mechanism. We calculate the stress and strain changes across the three-dimensional plate interface attributable to seismic waves from the earthquake by full wavefield simulation. The maximum magnitude of the dynamic strain tensor eigenvalues on the plate interface, where tremors likely occur, is approximately 10 -6 . The subducting slab geometry effectively amplifies triggering waves. The triggering Coulomb failure stress changes resolved for a thrust fault plane consistent with the geometry are estimated to be approximately 10-40 kPa. The relationship between the triggering stress and triggered tremor amplitude may indicate that the [[EQUATION]] of the rate-state-dependent friction law is 10 to 100 kPa.

scholarly journals Tectonic Tremors in the Northern Mexican Subduction Zone Remotely Triggered by the 2017 Mw8.2 Tehuantepec Earthquake

2020 ◽  
Author(s):  
Masatoshi Miyazawa ◽  
Miguel Ángel Santoyo
Keyword(s):  
Subduction Zone ◽  
Dynamic Strain ◽  
Plate Boundaries ◽  
Maximum Magnitude ◽  
Slab Geometry ◽  
Plate Interface ◽  
Wavefield Simulation ◽  
Stress Changes ◽  
Triggered Tremor ◽  
Mexican Subduction Zone

Abstract Surface waves from the 2017 Mw8.2 Tehuantepec earthquake remotely triggered tectonic tremors in the Jalisco region, approximately 1000 km WNW in the northern Mexican subduction zone. This is the first observation of tremor triggering in this region and one of the largest known examples of triggered tremor in the world. While prior studies found tectonic tremors triggered by teleseismic waves in subduction zones and plate boundaries, further investigation of tremor triggering is crucially important for understanding the causative mechanism. We calculate the stress and strain changes across the three-dimensional plate interface attributable to seismic waves from the earthquake by full wavefield simulation. The maximum magnitude of the dynamic strain tensor eigenvalues on the plate interface, where tremors likely occur, is approximately 10-6. The subducting slab geometry effectively amplifies triggering waves. The triggering Coulomb failure stress changes resolved for a thrust fault plane consistent with the geometry are estimated at approximately 10-40 kPa. The relationship between the triggering stress and triggered tremor amplitude may indicate that the aσ of the rate-state-dependent friction law is 10 to 100 kPa.

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