P and S wave travel time tomography of the SE Asia-Australia collision zone

Zenonos, A.; Siena, Luca De; Widiyantoro, Sri; Rawlinson, Nicholas

doi:10.1016/j.pepi.2019.05.010

Cited by 40 publications

(85 citation statements)

References 51 publications

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“…This approach has the advantage of allowing for more direct comparison between the V p , V s , and

\frac{V p}{V s}

models, which will all have similar raypath coverage. Potentially higher resolution models can be obtained for V p and V s by using all available data, and these are also presented in the supporting information (see Figures S1 and S2) along with comparable models, produced by Zenonos et al () (see Figures S3 and S4).…”

Section: Datasupporting

confidence: 53%

“…This approach is nonrobust and tends to produce

\frac{V_{p}}{V_{s}}

models which are dominated by anomalies that are present in the V p model. This is due to the lower number of raypaths and hence poorer resolution of the V s model in most local or regional earthquake tomography studies (e.g., Zenonos et al, ), as well as the ad hoc regularization that is imposed, which results in poorly constrained amplitudes. For d ( V p / V s ) (perturbations from a reference

\frac{V_{p}}{V_{s}}

model), the relative amplitudes of V p and V s are of great importance, and different regularization choices introduce arbitrary anomalies in d ( V p / V s ).…”

Section: Methodsmentioning

confidence: 99%

“…All events were relocated using the EHB algorithm (Engdahl et al, ), in which a nonlinear relocation scheme is applied in the presence of the radially stratified ak135 velocity model developed by Kennett et al (). The same selection criteria outlined in Zenonos et al (), Bijwaard et al (), and Amaru () were applied to arrival times contained in the data set; these criteria permit the use of arrival time residuals from local events (<25°) which are less than 7.5 s for P and S and teleseismic arrival time anomalies (>25°) which are less than 3.5 s for P and 7.5 s for S . The aforementioned criteria were determined empirically from density plots of ISC delay times versus epicentral distance (Bijwaard et al, ).…”

Section: Datamentioning

confidence: 99%

“…In both cases, the differences are not significant, particularly above ∼300 km depth. It is worth noting that a slightly different approach to choosing the optimum damping and smoothing parameters was used in the previous models of Zenonos et al (), which explains why their anomaly amplitudes tend to be smaller, particularly at greater depth where path coverage is lower. P wave, S wave, and

d ()(, \frac{V_{p}}{V_{s}})

models produced in this study using P and S wave arrival time data sets with identical source‐receiver combinations are shown in Figures S16–S18 from 100 to 600 km depth.…”

Section: Solution Stability and Model Resolutionmentioning

confidence: 99%

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Direct Inversion of S‐P Differential Arrival Times for Ratio in SE Asia

et al. 2020

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Southeast Asia lies within one of the most complex tectonic settings on Earth and exhibits a range of features, including strongly curved subduction zones, arc‐continent collision, and slab break‐off, which are not well understood. To help gain insight into mantle structure and processes beneath this region, we perform an inversion for variations in Vp, Vs, and VpVs structure using arrival time information from the ISC‐EHB catalog. The oceanic lithosphere subducting beneath Java is imaged as a positive dVp and negative d(Vp/Vs) anomaly. At 200 km depth, the forearc mantle beneath Sumatra and Java is revealed by positive dVp and d(Vp/Vs) anomalies which cease at Sumba island, where negative d(Vp/Vs) anomalies mark the presence of cold Australian lithosphere (down to 200–250 km depth) which is colliding with Sundaland. These negative d(Vp/Vs) anomalies depict a ∼WE trending structure that appears to correspond with the underthrusting of Australian continental crust. One notable salient has a location and shape which appears to coincide with those of ancient terranes or a Gondwana‐related microcontinent reconstructed by paleogeographic studies and may have been entrained in the subduction process. The velocity and d(Vp/Vs) patterns beneath the Banda Arc support the existence of a single curved subducting slab associated with rollback. The extreme extensional strike‐slip setting in Seram produces the highest positive d(Vp/Vs) anomalies in the model which may be due to one or more of widespread serpentinization, high concentrations of intraslab fluid‐filled faulting, and mantle upwelling.

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“…This approach has the advantage of allowing for more direct comparison between the V p , V s , and

\frac{V p}{V s}

Section: Datasupporting

confidence: 53%

“…This approach is nonrobust and tends to produce

\frac{V_{p}}{V_{s}}

\frac{V_{p}}{V_{s}}

model), the relative amplitudes of V p and V s are of great importance, and different regularization choices introduce arbitrary anomalies in d ( V p / V s ).…”

Section: Methodsmentioning

confidence: 99%

Section: Datamentioning

confidence: 99%

d ()(, \frac{V_{p}}{V_{s}})

models produced in this study using P and S wave arrival time data sets with identical source‐receiver combinations are shown in Figures S16–S18 from 100 to 600 km depth.…”

Section: Solution Stability and Model Resolutionmentioning

confidence: 99%

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Direct Inversion of S‐P Differential Arrival Times for Ratio in SE Asia

et al. 2020

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“…Because the slab on profile AA′ abuts the northern boundary of the model, the slab beneath the northern tip of Sumatra may continue beyond the northern boundary of the study area and penetrate to a deeper depth; however, referring to the slab on profile BB′ (on which the slab just penetrates across the 410‐km discontinuity), we do not consider that the slab on profile AA′ penetrates to a much deeper depth beyond the 410‐km discontinuity. Nevertheless, some P wave tomography models in the literature show that the slab beneath the northern tip of Sumatra penetrates to a depth of at least 500 km (Hall & Spakman, ; Pesicek et al, ; Richards et al, ; Zenonos et al, ), although some other studies suggest that the slab penetrates to a much shallower depth (approximately 250 km; Huang et al, ). Toward the SE, the slabs on profiles BB′, CC′, and DD′ (Figures b–d) begin to cross the 410‐km discontinuity.…”

Section: Resultsmentioning

confidence: 99%

Slab Morphology Beneath Northern Sumatra Revealed by Regional and Teleseismic Traveltime Tomography

et al. 2019

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An eikonal equation-based tomography method is used to invert the high-quality regional and teleseismic traveltime data recorded by 26 broadband seismic stations in northern Sumatra, following which we obtain the P and S wave velocity structures of the crust and mantle down to a depth of 800 km. The results of both P and S wave tomography clearly show that the Indo-Australian oceanic plate continuously penetrates downward beneath northern Sumatra and the maximum penetration depth varies approximately from 400 km at the northern tip of Sumatra to about 800 km around the southern boundary of our study area. Significant slab folding or bending reported in the literature as the main feature of the subducted slab beneath northern Sumatra is not found in our results. Instead, our tomographic images demonstrate only a less curved slab that mimics the shape of the Sunda Trench and volcanic arc and generally extends over depths from 120 to 450 km. P wave tomography shows broad and pronounced low-velocity anomalies beneath the island of Sumatra in the lower crust and uppermost mantle. Our model also reveals a slab tear approximately at 120-km depth, which has been documented in previous studies and considered to be related to the eruption of the Toba supervolcano.

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SASSY21: A 3-D seismic structural model of the lithosphere and underlying mantle beneath Southeast Asia from multi-scale adjoint waveform tomography

Wehner

Blom

Rawlinson

et al. 2021

Preprint

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We present the first continental-scale seismic model of the lithosphere and underlying mantle beneath Southeast Asia obtained from adjoint waveform tomography (often referred to as full-waveform inversion or FWI), using seismic data filtered at periods from 20 to 150 s. Based on >3,000 hr of analyzed waveform data gathered from ∼13,000 unique source-receiver pairs, we image isotropic P-wave velocity, radially anisotropic S-wave velocity and density via an iterative non-linear inversion that begins from a 1-D reference model. At each iteration, the full 3-D wavefield is determined through an anelastic Earth, accommodating effects of topography, bathymetry and ocean load. Our data selection aims to maximize sensitivity to deep structure by accounting for body wave arrivals separately. SASSY21, our final model after 87 iterations across seven period bands, is able to explain true-amplitude data from events and receivers not included in the inversion. The trade-off between inversion parameters is estimated through an analysis of the Hessian-vector product. SASSY21 reveals detailed anomalies down to the mantle transition zone, including multiple subduction zones. The most prominent feature is the (Indo-)Australian plate descending beneath Indonesia, which is imaged as one continuous slab along the 180° curvature of the Banda Arc. The tomography confirms the existence of a hole in the slab beneath Mount Tambora and locates a high S-wave velocity zone beneath northern Borneo that may be associated with subduction termination in the mid-late Miocene. A previously undiscovered feature beneath the east coast of Borneo is also revealed, which may be a signature of post-subduction processes, delamination or underthrusting from the formation of Sulawesi.Plain Language Summary Southeast Asia is one of the world's most tectonically active regions, as evidenced by frequent large earthquakes and volcanic eruptions. We present a large-scale 3-D seismic structural model of this region down to a depth of 800 km that reveals a variety of primary features, including beneath the poorly understood islands of Borneo and Sulawesi. This is possible thanks to the use of a sizable data set of earthquakes recorded by a large number of permanent and temporary stations located in Southeast Asia, and advanced imaging methodology that is better able to capture the true physics of seismic wave propagation compared to more traditional methods. Our new model is capable of resolving variations in seismic properties associated with ongoing subduction (when one tectonic plate descends into the mantle below another plate), particularly along the northern margin of the Australian plate beneath the Sunda Arc. More subtle anomalies associated with remnant subduction, which correspond to plate fragments that remain once subduction stops, can also be imaged. These results are important for achieving a better understanding of the subduction cycle, which plays a central role in plate tectonics, and has important implications for, among other things, the evolut...

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P and S wave travel time tomography of the SE Asia-Australia collision zone

Cited by 40 publications

References 51 publications

Direct Inversion of S‐P Differential Arrival Times for Ratio in SE Asia

Direct Inversion of S‐P Differential Arrival Times for Ratio in SE Asia

Slab Morphology Beneath Northern Sumatra Revealed by Regional and Teleseismic Traveltime Tomography

SASSY21: A 3-D seismic structural model of the lithosphere and underlying mantle beneath Southeast Asia from multi-scale adjoint waveform tomography

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