The underthrusting of continental crust during mountain building is an issue debate for orogens at convergent margins. We report three-dimensional seismic anisotropic tomography Taiwan that shows a nearly 90° rotation fabrics across 10- to 20-kilometer depth, consistent with the presence two layers deformation. upper dominated by collision-related compressional deformation, whereas lower Taiwan, mostly subducted Eurasian plate, convergence-parallel shear interpret this crustal shearing as...

Seismic traveltime tomography is commonly discretized by a truncated expansion of the pursued model in terms chosen basis functions. Whether parametrization affects actual resolving power given data set as well robustness resulting earth has long been seriously debated. From perspective resolution, however, there one important aspect issue seismic that yet to be systematically explored, is, space–frequency localization parametrization. In fact, two most common parametrizations tend enforce...

Three‐dimensional tomographic images of the subducting Philippine Sea slab and fore‐arc mantle beneath NE Taiwan westernmost Ryukyu were generated in this study. More than 5600 events recorded simultaneously by seismic networks Japan relocated for inversion variations V P , S / . Analysis trade‐off between data variance reduction model helps to determine appropriate strictness regularization avoid either overinterpretatioin or underinterpretation data. The parameters also chosen ensure...

An improved inversion technique is needed to effectively separate the frequency dependence of source from intrinsic attenuation medium. We developed a cluster‐event method (CEM) in which clusters nearby events, instead individual pair with stations form basis for measurements Q value and corner ( f c ). assume that raypaths one cluster station share an identical while each event same allowed only process. This approach largely reduces degrees freedom achieve robust inversion. use...

Abstract This study focuses on developing and evaluating the broadband ocean bottom seismometer (Yardbird-BB OBS) in Taiwan. The Yardbird-BB OBS is a crucial instrument for recording seismic signals deep-sea environments. Rigorous testing ensures optimal performance data capabilities. Following assembly, undergoes 3–6 month deployment test deep sea, capturing worldwide. Data from 2016 2017 deployments Okinawa Trough analyze significant events, including magnitude 7.8 earthquake New Zealand...

In 2024, the Mw 7.4 eastern Taiwan earthquake highlights Taiwan’s status as one of most seismically active areas, driven by complex interaction between European Plate (EP) and Philippine Sea (PSP). This dense seismicity provides a unique opportunity to investigate rupture properties. The corner frequency, key parameter for understanding kinematic properties, is challenging measure due site effect trade-off frequency attenuation t*. Jian Kuo (2024) proposed Cluster Event Method 2...

Slow earthquakes, distinct from regular earthquakes in their gradual release of seismic energy, play a key role stress accumulation and at subduction plate interfaces have been proposed as potential precursors to large earthquakes. In the northern Ryukyu Trench, Philippine Sea Plate subducts beneath Eurasian Plate, region is characterized by few over past several centuries, including magnitude 8.0 event 1911 near Kikai Island. Although interplate coupling crustal heterogeneity this area...

Differential travel times between S (or diffracted ) and SKS were measured to study the global distribution of shear wave velocity heterogeneity in lowermost 250 km mantle (the D″ region). Commencing with ∼3000 ‐ variable qualities, we minimize uneven path coverage by thinning redundantly sampled regions (e.g., Fiji‐Tonga North America corridor) collect additional data for sparsely areas, especially Southern Hemisphere. About 1500 paths retained, distributed reconcile both high‐density...

To explore upper mantle heterogeneity beneath the North Atlantic we have measured 70 SS ‐ S differential travel times using waveform cross‐correlation method. Both two‐way preliminary reference earth model (PREM) and J‐B (Jeffreys‐Bullen) residuals exhibit a maximum variation of 17 s, ranging from −10 to 7 −9 8 respectively. The lack correlation between residuals, along with strong suggests that eliminate source receiver effects sample anomalies near bounce points without being strongly...

Abstract Mapping both isotropic and anisotropic velocity structures of the crust provides insight into dominant mechanisms that produce deformation. We performed ambient noise tomography for shear V s in Tohoku region, Japan, where plate kinematics remains simple as Pacific is subducting under Okhotsk plate. Cross‐correlation functions were retrieved from Hi‐net recordings phase velocities 3–16 measured, followed by a one‐step, wavelet‐based multiscale inversion its azimuthal anisotropy. The...

We have formulated a new class of plate‐bending equations which simulates the flexure lithosphere at mid‐ocean ridges. The stress‐accumulation effect in growing (moving and thickening) significantly changes flexural behavior. It is shown that plate flexes more easily than conventional static due to fact bending stress vanishes on base plate. apply this model East Pacific Rise. Compared with Madsen et al. (1984), fits gravity topography observations are improved. Assuming thickness varies...

A broad-band ocean-bottom seismometer (OBS) deployed ∼180 km east of Taiwan provides a first glimpse into the upper mantle beneath westernmost section Philippine Sea or Huatung basin (HB). We measured interstation phase velocities Rayleigh waves between OBS and stations on eastern coast Taiwan. The show smooth variations from 3.8 to 3.9 s−1 for periods 25–40 s. In this short period range, are comparable those characterizing 15–30 Ma Parece-Vela Sea. Modelling finite-frequency effect proves...

Abstract The Taiwan mountain belt between the Eurasian and Philippine Sea plate is a rare example for an orogen bracketed by two opposite‐verging subduction zones. influences of double zones on regional dynamics have long remained unknown. In this study lithospheric deformation mantle circulation in region are calculated with subduction‐collision models. results show that limitedly deformed subducted separates highly deforming above from below. edge flow driven rollback slab dominates...

Abstract In this study, we reveal the deformational structure of crust northern part Ryukyu Arc and Okinawa Trough using ambient noise tomography. Compared with southern Ryukyu, segment exhibits a wide shallow basin, without localized thinning, slow extension rates, highly arc‐oblique, right‐lateral retreat Arc. We present both isotropic azimuthally anisotropic shear‐wave velocity models data recorded by an ocean‐bottom seismometer array nearby island stations. The model demonstrates...

A global map of shear velocity in the D″ layer results from inversion 340 differential travel times diffracted S ( SH ) minus SKS SV Sd ‐ ), long‐period records seismic networks. The two‐phase design reduces contamination upper mantle heterogeneities and errors location origin time events. Additional corrections are made for (1) azimuthal anisotropy at stations where wave splitting parameters available (2) perturbations due to lower asphericity, although both effects minor compared with...

The termination of the Ryukyu trench against Eurasia and oblique subduction Philippine Sea plate create a subduction‐collision complex offshore Taiwan, which has not previously been elucidated in detail. We combine traveltime data from seismic networks Taiwan Japan to better illuminate how subducting slab deforms this zone. More than 5000 events recorded by both were relocated with double‐difference method using an optimal regional one‐dimensional velocity model. seismicity indicates that...

Typhoons inflict large damage to societies, but are usually difficult monitor in close proximity real-time without expensive instruments. Here we study the possibility of using seismic waveforms on seafloor and land turning a far away or approaching typhoon. Up 67% typhoons making landfall Taiwan come from eastern shore, so that deployed broadband ocean-bottom seismometers (OBSs) offshore 2006 ground motion generate ocean waves, which pressure signals water column before being transmitted as...

The shear velocity structure in the lowermost 500 km of mantle beneath Caribbean and surrounding areas is determined by seismic tomography applied to a suite Sd ‐ SKS , ScS S ( Scd + Sbc )‐ ‐( ) differential times, where pair overlapping triplication arrivals produced wave interaction with an abrupt increase at top D″ region. inclusion inversion, first for deep tomographic model, possible because widespread presence discontinuity improved ray path sampling provided yields vertical resolution...

Short‐period stations ENT and NSK in northern Taiwan have frequently recorded split S waveforms from earthquakes the underlying subduction zone. To determine splitting parameters together with objective, straightforward error estimations, we employ a waveform cross‐correlation method. The for each measurement is estimated by translating lower limit of 95% confidence interval coefficient into azimuth time. Only measurements regions excluding zero delay time are accepted as data. We also use...

Broadband records from ocean-bottom seismometers deployed in the Okinawa trough and Huatung basin were analyzed to provide seafloor noise characteristics detection thresholds for teleseismic body surface waves. Ambient levels on horizontal components are 10-40 dB higher than vertical component, with sensor seated of sediment. On components, infragravity waves 10-30 more energetic at shallower sites (≤2000 m depth) deeper site (~4700 m). From 0.03 0.2 Hz, comparable that broadband stations...