scholarly journals Initial Result of P Wave Tomography Model in Sunda-Banda Arc Transition using FMTOMO

2021 ◽  
Vol 873 (1) ◽  
pp. 012057
Author(s):  
P T Brilianti ◽  
Haolia ◽  
M I Sulaiman ◽  
S S Angkasa ◽  
S Widyanti ◽  
...  
Keyword(s):  
Velocity Structure ◽  
Tectonic Setting ◽  
Shallow Depth ◽  
P Wave ◽  
Benioff Zone ◽  
Target Area ◽  
Fast Marching Method ◽  
Eurasian Plate ◽  
Fast Marching ◽  
Banda Arc

Abstract Our study area is located near island Sumbawa, Sumba, Flores, West Timor, Indonesia and East Timor, popularly known as Sunda-Banda arc transition zone. The tectonic setting is mainly controlled by the movement of the oceanic lithosphere Indo-Australian plate subducting the Eurasian plate and Northward migration of Australian continental lithosphere into western Banda-arc in the region of Flores, Sumba and Timor island. We tried to image velocity structure beneath these regions using regional events and tomography inversion model. We collected 5 years of regional events from the Indonesian Agency of Meteorology, Climatology and Geophysics. In total, we reserved 3186 events recorded on 29 stations. For data processing, we used fast marching method as ray tracing between sources and receiver. We then employed subspace inversion as the tomography procedure to estimate the best velocity model representing the tectonic model in the region. Hypocenter data distribution is concentrated on shallow parts of the region and along the Benioff zone down to a maximum depth of 400 km. One of challenge of this study is that although events are abundance, the stations used are mostly located onshore and does not extend in the south-north direction that leads us to under determined problem in the inversion process. However, checker-board models show most our target area can be retrieved to its initial model with sign of smearing effects shown start from a depth of 50 km. After six iteration and optimized selection of damping and smoothing parameters, we observed low velocity anomaly under Bali, Lombok, Sumba, East Nusa Tenggara at shallow depth that may be related with volcanic activity. Deeper low anomaly can also be seen that may be related with partial melting process. A band of fast velocity is clearly seen that goes deepen to the north depicting subducting slabs own to a depth of 300 km. We also observed a possible of fast velocity in the northern part of our stations at shallow depth that we believe may represent the back arc thrust.

scholarly journals Preliminary Model of P-Wave Tomography Beneath Central Java using FMTOMO

2021 ◽  
Vol 873 (1) ◽  
pp. 012064
Author(s):  
M Yasir ◽  
P T Brilianti ◽  
S S Angkasa ◽  
S Widyanti ◽  
I Herawati ◽  
...  
Keyword(s):  
Tectonic Setting ◽  
P Wave ◽  
Benioff Zone ◽  
Good Resolution ◽  
Ocean Bottom Seismometer ◽  
Low Velocity ◽  
Fast Marching ◽  
Megathrust Earthquakes ◽  
Central Java ◽  
Wave Tomography

Abstract The tectonic setting of Java Island is mainly controlled by the collision of Indo-Australian plate subducting the Eurasian plate. The high collision activity of Eurasian and Indo-Australian plates often causes megathrust earthquakes and the rise of arc magmatism that includes volcanic eruption. This study aims to determine the tectonic pattern beneath Central Java based on P-wave tomography inversion. We used the fast-marching method as ray tracing and subspace inversion to image subsurface velocity model to a depth of 150 km. The data used in this study are catalogue events data derived from a temporary seismometer network MERAMEX installed around central Java and DOMERAPI installed surround Mt. Merapi and Mt. Merbabu. We also include events collected from the International Seismological Centre. In total, we processed 563 earthquake events to illustrate velocity structures under central Java. The checker-board model shows that good resolutions can be identified at shallow depth, including offshore south Java contributed from Ocean Bottom Seismometer data. In vertical axis, good resolution models can be expected down to a depth 150 km following rich events from the Benioff zone. Current P wave model show a distinct low velocity zone under Mt Merapi that can be seen down to a depth of 40 km, suggesting a possible separated deep magma reservoir. To the south of Mt Merapi area also shows a low-velocity band that may be related with the southern mountain arc. Additionally, the northern part of Mt. Merapi displays a band of strong low-velocity anomaly to the East and West with the anomaly in the Eastern Part seems to have a deeper extension to a depth of ~50 km. We related this anomaly with Merapi Lawu Anomaly and Kendeng basin. Our results show a similar result with the previous tomography models in this region.

scholarly journals Preliminary Results of Double Difference Tomography at Sunda-Banda Arc

2021 ◽  
Vol 873 (1) ◽  
pp. 012067
Author(s):  
Haolia ◽  
M. I. Sulaiman ◽  
P. T. Brilianti ◽  
R. P. Nugroho ◽  
I. Madrinovella ◽  
...  
Keyword(s):  
Tectonic Setting ◽  
Active Volcano ◽  
P Wave ◽  
Double Difference ◽  
Benioff Zone ◽  
Good Resolution ◽  
S Wave ◽  
Low Velocity ◽  
The North ◽  
Banda Arc

Abstract The Sunda-Arc transition to the Banda Arc is located on the south of the Flores Island, Indonesia, where the Australian lithosphere is moving to the north direction. On-going subduction process dictates the tectonic setting though some studies also suggest a collision and obduction may occur in the past due to of plate buoyancy. This area has active seismicity with frequent large magnitude events. To better understand the tectonic system in this region, we performed double-difference tomography inversion using regional events. We obtained the data catalog from the Indonesian Agency of Meteorology, Climatology, and Geophysics ranging from 116° to 125° east longitude and -6.5° to 12.5° latitude. We collected 4312 events data, detected from 15 stations from January 2015 to December 2019. Final relocated hypocenters showed a reduced fixed-depth problem and a more clustered event, although some deep events disappear. Most events are related to the subducting Benioff zone with some clustered events in the northern area may be related to back-arc thrust. We also observed clustered events near active volcano region and reduced shallow seismicity region to the west of the Timor Island. Resolution test using the checkerboard and Derivative weigh Sum (DWS) shows that fair P wave resolution can be achieved until 300 km, although a smearing start to show at a deeper depth. However, due to lack of arrival S wave data, the resolution test suggest good resolution can only be seen until a depth of 100 km. Tomogram P and S wave models show a clear dipping subducting slab from south to North down to a 250 km. We also spot a fast velocity band near the Timor Island area that similar to the previous tomography study, interpreted as sliver forearm. We spotted a band of lower Vp, lower Vs and higher Vp/Vs at shallow depth close to the volcanic line and we interpreted this as a zone of higher temperature, that may relate to magmatic activity in this region. We also noticed a zone of low velocity and higher Vp/Vs that may relate with dehydration and partial melting. However, we feel this still uncertain due to low Vs resolution.

scholarly journals Comparison of P-Wave Tomography Model in Sunda-Banda Arc by Using Data from BMKG and ISC

2021 ◽  
Vol 873 (1) ◽  
pp. 012058
Author(s):  
P T Brilianti ◽  
M S Haq ◽  
Haolia ◽  
M I Sulaiman ◽  
R P Nugroho ◽  
...  
Keyword(s):  
Delay Time ◽  
Tectonic Setting ◽  
Depth Estimation ◽  
P Wave ◽  
Eurasian Plate ◽  
Low Velocity ◽  
Data Set ◽  
Local Agency ◽  
Eastern Area ◽  
Shallow Part

Abstract The tectonic setting of our study area is located between the Island of Java and Timor Leste. The complexity of this region is started with two different plates, The Indo-Australian plate and the Eurasian plate that move with different orientations and convergence rate. This area also shows active seismic activity and has a series of active volcanoes as a product of subduction and collision. To deepen understand this area, we perform delay time tomography using FMTOMO package that includes 3-D finite-difference based ray tracing and sub-space inversion procedure. We used two different sets of data, the first one is 4 years data catalog from the Indonesian Agency of Meteorology, Climatology and Geophysics, and the second one is 47 years of data from the International Seismological Centre. Data from the local Indonesian show agency shows a fewer number of events but more focus clusters. Meanwhile, the data from ISC catalog has more events and evenly distributed data. However, we also noticed that data from ISC has cluster events located at the same depth that can be improved with events relocation for better depth estimation. The Checkerboard models from both data set show a comparable result, though data from ISC show a better recovered model at a deeper depth and shallow part in the eastern area. The checkerboard from the local Agency shows slightly better results in the shallow part. Next, we invert delay time for each data set using we optimized damping and smoothing parameters. Final tomogram models show that data from the local Agency show a more continuous fast velocity band representing a downgoing subducting slab and possible back-arc thrust while results from the ISC data show a more detached fast velocity band that could be contributed from fixed depth problem in the data set. However, we noticed that data from ISC show a higher amplitude low-velocity anomaly especially in the shallow depth

scholarly journals Complex structure of the lithospheric slab beneath the Banda arc, eastern Indonesia depicted by a seismic tomographic model

2011 ◽  
Vol 1 (1) ◽  
pp. 1 ◽  
Author(s):  
Sri Widiyantoro ◽  
Jeremy D. Pesicek ◽  
Clifford H. Thurber
Keyword(s):  
Upper Mantle ◽  
Velocity Structure ◽  
Complex Structure ◽  
P Wave ◽  
Zone Structure ◽  
Study Region ◽  
Tomographic Images ◽  
P Wave Velocity ◽  
Banda Arc ◽  
Back Arc

Seismic tomography with a non-linear approach has been successfully applied to image the P-wave velocity structure beneath the Banda arc in detail. Nearly one million compressional phases including the surfacereflected depth phases pP and pwP from events within the Indonesian region have been used. The depth phases have been incorporated in order to improve the sampling of the uppermantle structure, particularly below the Banda Sea in the back-arc regions. For the model parameterization, we have combined a highresolution regional inversion with a low-resolution global inversion to allow detailed images of slab structures within the study region and to minimize the mapping of distant aspherical mantle structure into the volume under study. In this paper, we focus our discussion on the upper mantle and transition zone structure beneath the curved Banda arc. The tomographic images confirm previous observations of the twisting of the slab in the upper mantle, forming a spoon-shaped structure beneath the Banda arc. A slab lying flat on the 660 km discontinuity beneath the Banda Sea is also well imaged. Further interpretations of the resulting tomograms and seismicity data support the scenario of the Banda arc subduction rollback.

scholarly journals Microseismic P-Wave Travel Time Computation and 3D Localization Based on a 3D High-Order Fast Marching Method

Sensors ◽  
2021 ◽  
Vol 21 (17) ◽  
pp. 5815
Author(s):  
Yijia Li ◽  
Jing Wang ◽  
Zhengfang Wang ◽  
Qingmei Sui ◽  
Ziming Xiong
Keyword(s):  
Travel Time ◽  
Dimensional Space ◽  
Three Dimensional ◽  
High Order ◽  
P Wave ◽  
Fast Marching Method ◽  
Fast Marching ◽  
Velocity Models ◽  
Wave Travel ◽  
Three Dimensional Space

The travel time computation of microseismic waves in different directions (particularly, the diagonal direction) in three-dimensional space has been found to be inaccurate, which seriously affects the localization accuracy of three-dimensional microseismic sources. In order to solve this problem, this research study developed a method of calculating the P-wave travel time based on a 3D high-order fast marching method (3D_H_FMM). This study focused on designing a high-order finite-difference operator in order to realize the accurate calculation of the P-wave travel time in three-dimensional space. The method was validated using homogeneous velocity models and inhomogeneous layered media velocity models of different scales. The results showed that the overall mean absolute error (MAE) of the two homogenous models using 3D_H_FMM had been reduced by 88.335%, and 90.593% compared with the traditional 3D_FMM. On that basis, the three-dimensional localization of microseismic sources was carried out using a particle swarm optimization algorithm. The developed 3D_H_FMM was used to calculate the travel time, then to conduct the localization of the microseismic source in inhomogeneous models. The mean error of the localization results of the different positions in the three-dimensional space was determined to be 1.901 m, and the localization accuracy was found to be superior to that of the traditional 3D_FMM method (mean absolute localization error: 3.447 m) with the small-scaled inhomogeneous model.

scholarly journals Early Results of P Wave Regional Tomography Study at Sunda-Banda Arc using BMKG Seismic Network

2021 ◽  
Vol 873 (1) ◽  
pp. 012065
Author(s):  
M S Haq ◽  
Haolia ◽  
M I Sulaiman ◽  
I Madrinovella ◽  
S Satiawan ◽  
...  
Keyword(s):  
Northern Region ◽  
P Wave ◽  
Eurasian Plate ◽  
Lower Velocity ◽  
Seismicity Pattern ◽  
Early Results ◽  
Australian Plate ◽  
Banda Arc ◽  
Australian Continent ◽  
Back Arc

Abstract The plate movement, geological structure, magmatism, and seismic activity in the area of Bali to East Nusa Tenggara are mainly related with the subducting of Indo-Australian Plate underneath the Eurasian plate. The complexity is added with the recent collision of Australian continent lithosphere with the western Banda arc, along the islands of Flores, Sumba and Timor island. Our study area is known as the Sunda-Banda arc transition. With the aim of imaging subsurface structure, we perform seismic tomography inversion using regional events. We collected 5 years of earthquake data (January 2015 – December 2019) from the Indonesian Agency of Meteorology, Climatology, and Geophysics (BMKG). The output of our data processing is not limited to only P wave velocity model, but also relocated seismicity pattern in the region. In general, seismicity pattern shows dominant shallow events in the south that progressively shift into deeper events in the north down to a few 500 km, marking a dipping subduction zone in this region. A group of shallow events down to a depth of 50 km is also seen at the norther region that may relate to back-arc thrust activity. P wave tomogram model show a lower velocity perturbation at a depth of 30 km that could be associated with magmatic activity along the volcanic front line. Higher P wave perturbation model are spotted at two different zones, the first one is marking a dipping Indo-Australian plate down to depth of 400 km. We noticed that the angle of dipping is steeper in the Eastern part compared to the Western part. The second a relatively flat at shallow depth at the northern region from the island of Lombok to Nusa Tenggara Timur that may mark the back-arc thrust region

scholarly journals 1-D velocity structure modelling of the Earth's Crust in the NW Dinarides

2021 ◽  
Author(s):  
Gregor Rajh ◽  
Josip Stipčević ◽  
Mladen Živčić ◽  
Marijan Herak ◽  
Andrej Gosar ◽  
...  
Keyword(s):  
Crustal Structure ◽  
Velocity Structure ◽  
Pannonian Basin ◽  
Stable Solution ◽  
P Wave ◽  
Small Scale ◽  
Depth Range ◽  
Eurasian Plate ◽  
Low Velocity ◽  
Velocity Models

Abstract. The investigated area of the NW Dinarides is located at the NE corner of the Adriatic microplate and is bordered by the Adriatic foreland, the Southern Alps, and the Pannonian basin. Its complex crustal structure is the result of interactions among different tectonic units, mainly the Eurasian plate and the Adriatic microplate. Despite numerous seismic studies in this tectonically complex area, there is still a need for a detailed, small scale study focusing mainly on the upper, brittle part of the crust. We investigated the crustal velocity structure with 1-D simultaneous hypocenter-velocity inversion using routinely picked P wave arrival times. Most of the computed models converged to a stable solution in the depth range between 0 and 26 km. We further evaluated the inversion results with hypocenter shift tests, high and low velocity tests, and relocations. This helped us to select two best performing velocity models for the whole study area. Based on these results and the seismicity distribution, we further divided the study area into three parts, redefined the earthquake-station geometry, and performed inversion for each part separately to gain better insight into the crustal structure of each subregion. Median velocities in the upper 20 km of the crust in the eastern subregion are lower compared to the regional median and the median of the other two subregions. The northwestern and southwestern subregions are very similar in terms of crustal structure between about 8 and 23 km depth. The largest difference between them is observed in the upper 8 km, with higher median velocities in the southwestern subregion. Compared to the model currently used at Slovenian Environment Agency to locate earthquakes, the velocity models obtained show higher velocities in the upper 30 km depth and agree very well with some of the previous studies. In addition to general structural implications and a potential for improving seismic tomography results, the new 1-D velocity models can also be used for fast routine earthquake location and for detecting systematic travel time errors in seismological bulletins.

scholarly journals Structure of the SW Iberian Margin from Combined Wide-angle and Multichannel Seismic Reflection Data (FRAME Project)

2020 ◽  
Author(s):  
Ricardo Correia ◽  
Manel Prada ◽  
Valenti Sallares ◽  
Irene Merino ◽  
Alcinoe Calahorrano ◽  
...  
Keyword(s):  
Velocity Structure ◽  
Tectonic Setting ◽  
P Wave ◽  
Ocean Bottom ◽  
Wide Angle ◽  
Thrust Faults ◽  
Acoustic Basement ◽  
Seismic Reflection Data ◽  
The North ◽  
Iberian Margin

<p>The SW Iberian Margin has a complex tectonic setting and crustal structure derived from a succession of rift events related to the opening of North Atlantic and Neotethys, from the Mesozoic to the Lower Cretaceous, and subsequent compression between Africa and Eurasia from the Lower Oligocene to present. This setting led to the reactivation of pre-existing strike-slip and extensional faults enhancing the seismogenic and tsunamigenic potential of the area. Thus, understanding of lithospheric structure along the SW Iberian Margin is not only important to study the rifting evolution but also to characterize the distribution of major lithospheric-scale boundaries, currently active and potentially capable of generating great seismic events of similar magnitude to the catastrophic 1755 Lisbon tsunamigenic earthquake, with estimated M<sub>W</sub>>8.5.</p><p>To this end, we use spatially coincident wide-angle seismic (WAS) and multichannel seismic (MCS) data collected along a ~320 km-long, NW-SE trending transect across the SW Iberian margin, during the FRAME survey in 2018. WAS data were recorded with by 24 ocean bottom seismometers and hydrophones (OBS/H), deployed each ~10km, while MCS data was recorded with a 6 km-long streamer. From NW to SE, the transect runs from the Tagus Abyssal plain to the westernmost extension of the Gulf of Cadiz area, across three major thrust faults: the Marquês de Pombal fault, São Vicente fault, and Horseshoe fault.</p><p>We applied joint refraction and reflection travel-time tomography using a combination of WAS refractions and reflections and MCS reflections to invert for the 2D P-wave velocity structure of the crust and uppermost mantle, and the geometry of the main seismic interfaces, namely the top of the acoustic basement and the Moho. The combination of WAS and MCS reflection travel-times brings a significant increase in the resolution of the tomographic model, and especially in the definition of the geometry of the inverted reflectors (i.e. top of the basement), because MCS data has a higher spatial sampling than WAS data in these shallow regions.</p><p>In the preliminary model, the Moho shallows beneath the north-eastward continuation of the Horseshoe Basin and the Gorringe Bank, coinciding with the location of the three major thrust faults mentioned before, and defining three major crustal blocks along the model. Further analysis of deep seismic phases from WAS records should provide additional information on the geometry and extent of these three major thrust faults.</p>

scholarly journals A Comparison of Local Path Planning Techniques of Autonomous Surface Vehicles for Monitoring Applications: The Ypacarai Lake Case-study

Sensors ◽  
2020 ◽  
Vol 20 (5) ◽  
pp. 1488
Author(s):  
Federico Peralta ◽  
Mario Arzamendia ◽  
Derlis Gregor ◽  
Daniel G. Reina ◽  
Sergio Toral
Keyword(s):  
Path Planning ◽  
Random Trees ◽  
Fast Marching Method ◽  
Fast Marching ◽  
Planning Techniques ◽  
Advantages And Disadvantages ◽  
Autonomous Surface Vehicle ◽  
Local Path Planning ◽  
Custom Made ◽  
Local Path

Local path planning is important in the development of autonomous vehicles since it allows a vehicle to adapt their movements to dynamic environments, for instance, when obstacles are detected. This work presents an evaluation of the performance of different local path planning techniques for an Autonomous Surface Vehicle, using a custom-made simulator based on the open-source Robotarium framework. The conducted simulations allow to verify, compare and visualize the solutions of the different techniques. The selected techniques for evaluation include A*, Potential Fields (PF), Rapidly-Exploring Random Trees* (RRT*) and variations of the Fast Marching Method (FMM), along with a proposed new method called Updating the Fast Marching Square method (uFMS). The evaluation proposed in this work includes ways to summarize time and safety measures for local path planning techniques. The results in a Lake environment present the advantages and disadvantages of using each technique. The proposed uFMS and A* have been shown to achieve interesting performance in terms of processing time, distance travelled and security levels. Furthermore, the proposed uFMS algorithm is capable of generating smoother routes.

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