###### Abstract
One such study covers the two Benioff zones that lie in opposite directions and form a double subduction pattern in the Molucca Sea Plate [5; 7; 8; 10; 13]. The subducted slab under the Sangihe Arc can be identified as far down as the mantle transition zone layer at a depth of \(\sim\)650 km; the subducted slab under the Halmahera Arc reaches the solid upper asthenosphere layer at a depth of \(\sim\)250 km [8]. According to [PERSON] et al. [10], the subducting slab to the east under the Halmahera Arc subducts at an angle of \(\sim\)45\({}^{\circ}\) and reaches a depth of \(\sim\)230 km; [PERSON] and [PERSON] [20] show that it reaches depths of \(\sim\)400 km, which is in line with recent research [21] that used 3D earthquake data distribution plots from ISC-EHB to identify slab configurations that were not modeled by slab2. [PERSON] and [PERSON] [12] showed that the subducted slab in the Sangihe Arc at depths of \(\sim\)250 to 350 km has a seismic gap, while the tomography image of the slab appears to be continuous. Tomographic studies have been carried out by previous researchers, including [PERSON] et al. [22] who used P-phase travel time data from ISC bulletins; their work shows a high-velocity zone that forms a double subduction of the Molucca Sea Plate. The slab is subducted to the west under the Sangihe Arc and reaches to the lower mantle. Meanwhile, the slab that subducts to the east under the Halmahera Arc reaches a depth of 400 km, which is conformable with the results of the study by [PERSON] and [PERSON] [23]. This research was later updated by [PERSON] [24] who shows that the subducted slab to the west reaches the lower mantle with a folded-looking slab. [PERSON] et al. [25] also detected a high-velocity zone in the form of bipolar subduction. Meanwhile, [PERSON] et al. [26] showed that the Molucca Sea Plate has a positive velocity anomaly with unique asymmetry. [PERSON] and [PERSON] [27; 28] showed that the subduction of the Molucca Sea Plate \(\sim\)5 Ma ago propagated from south to north; they were able to detect the Molucca Sea Plate using anisotropic tomography. [PERSON] et al. [29], using data from ISC-EHB, show the high-velocity Vp and Vs of the double subduction of the Molucca Sea Plate in which the high Vp reached a depth of \(\sim\)700 km beneath the Sangihe Arc and \(\sim\)400 km beneath the Halmahera Arc. The high Vs reached a depth of \(\sim\)500 km, which is in positive agreement with a study performed by [PERSON] et al. [21] who used only P-wave data. [PERSON] et al. [30] showed that negative Vp/Vs anomalies can reach \(\sim\)160 km, and positive Vp/Vs anomalies can reach depth of \(\sim\)200 km. Another study by [PERSON] et al. [31] observed the mantle flow using seismic anisotropy. Their study shows that beneath the Halmahera Arc the sub-slab mantle flow is oriented oblique to the Halmahera trench, while the sub-slab mantle flow beneath the Sangihe Arc runs in a parallel direction to the Sangihe trench. According to previous research, tomography is generally based on data from global teleseismic earthquakes within a broad region, producing a tomographic image with a broad resolution that displays only relatively large objects. Tomography around the Molucca Sea region usually only shows the main features of the Molucca Sea Plate [22; 23; 26; 29]. Several local researchers in the Molucca Sea area have used different methods [2; 17; 18]. However, their results extend only up to the layer of the Earth's crust; the tomographic results have not shown anomalies of 3D velocity structures due to volcanic activity in the subduction zone.