Tai-Lin Tseng

• PhD
• Professor (Associate) at National Taiwan University

Two earthquakes having almost the same magnitude occurred in the Hualien area of Taiwan in 2018 and 2019. The 2018 earthquake had a magnitude ML 6.2 produced severe destruction; however, the 2019 earthquake (ML=6.3) did not cause any severe damage. The P-Alert Strong Motion Network provides real-time shakemaps, in addition, to earthquake early warn...

The average anisotropy beneath Anatolia is very strong and is well constrained by shear-wave splitting measurements. However, the vertical layering of anisotropy and the contribution of each layer to the overall pattern is still an open question. Here, we construct anisotropic phase-velocity maps of fundamental-mode Rayleigh waves for the Anatolia...

The Arabia‐Eurasia continental collision created the Caucasus Mountains and the Anatolian and Iranian plateaus. Between the two plateaus, the Armenian Highland features young Holocene‐aged volcanoes. In this study, the P‐wave receiver functions from a new seismic array reveal a thick crust (up to ~52 km thick) beneath the Central Greater Caucasus a...

The Anatolian region is an area with very heterogeneous crustal structure accompanied by large velocity contrasts. Despite the complexity of the region, the detailed crustal structure remains to be unraveled. In this study, we first measure the dispersion curves of Rayleigh waves between 1,721 pairs of station and then invert these dispersion curve...

We proposed an effective approach to improve the accuracy of offshore earthquake location in the earthquake early warning (EEW) system of Taiwan. The EEW system was built upon Geiger's method for earthquake location that requires a set of initial estimates (epicenter, depth, and origin time). Because the initial epicenter highly depends on the loca...

A new algorithm has been developed in this study that can automatically determine regional moment tensor (MT) and its centroid depth with real-time waveforms; it can do this within 2–4 min of an earthquake notice issued by the Central Weather Bureau (CWB). The program selects 3–7 BATS (Broadband Array in Taiwan for Seismology) stations based on thr...

Changes in groundwater level during earthquakes have been reported worldwide. In this study, field observations of co-seismic groundwater-level changes in wells under different aquifer conditions and sampling intervals due to near-field earthquake events in Taiwan are presented. Sustained changes, usually observed immediately after earthquakes, are...

In 2013, a new network of broadband seismic stations was deployed in the Caucasus region. Broadband displacement data are inverted for the seismic moment tensor of two medium-sized earthquakes occurring in northeast Georgia (17 September 2013, Mw~5.1) and northern Armenia (26 May 2014, Mw~3.6), respectively. The peak ground velocity (PGV) is estima...

Cross-correlation of 3 years of ambient seismic noise recorded at 35 seismic stations deployed in Caucasus region yields hundreds of short-period surface-wave phase-speed dispersion curves on inter-station paths. We inverted these measurements using two techniques to construct tomographic images of the principal geological units of Caucasus. High-r...

The Caucasus region is at the boundary between Eastern Europe, Central Asia, and the Middle East. The continuous North-South compression of the collision not only produced the Caucasus mountain belts but also the westward extrusion of the wedged Anatolia block. In comparison to the surrounding regions, the seismicity in the Caucasus is relatively h...

The continental collision between Arabia and Eurasia created large strike-slip faults in Turkey as well as mountains in the Caucasus and the volcanic plateau between them. In this study, we use regional waveforms of a new seismic array deployed between 2008 and 2012 to constrain the focal mechanisms and depths of small to moderate sized earthquakes...

West–east extension is a prominent tectonic feature of southern and central Tibet despite ongoing north–south (N–S) convergence between India and Eurasia. Knowledge of deep structure beneath the N–S trending rifts is key to evaluating models proposed for their origin, including gravitational collapse, oblique convergence along the arcuate plate bou...

We present a three-dimensional (3D) hybrid method that interfaces the spectral-element method (SEM) with the frequency-wavenumber (FK) technique to model the propagation of teleseismic plane-waves beneath seismic arrays. The accuracy of the resulting 3D SEM-FK hybrid method is benchmarked against semi-analytical FK solutions for 1D models. The accu...

The Moho is not always a sharp interface; but seismic phase SsPmp yields robust, physically averaged estimates of crustal thickness (virtual deep seismic sounding, VDSS). In S. Tibet where the Moho is as deep as 75 km, bimodal distribution of earthquake depths, with one peak in the upper crust and the other below the Moho, generated much interest i...

Surrounded by seismicity and other manifestations of active deformation, the Ordos plateau, or the western portion of the North China craton (NCC), is a uniquely stable terrane in Asia. Results from virtual deep-seismic sounding and crustal receiver functions suggests that the crust under the eastern Ordos is thicker (at least 60 km) than expected...

We investigate the spatial and temporal variations of b-values before twenty-three earthquakes with ML≥6.0 in the Taiwan region from 1999 to 2009. We estimate the spatial distribution of b-values within a one-year period before the occurrence of investigated earthquakes. It shows that the epicenters of those earthquakes are located predominately in...

Using data from regional earthquakes recorded by the Hi-CLIMB array in Tibet, we model P-wave arrival times to constrain the velocity structure in the crust and the upper mantle in central and western Tibet. Of more than 30 high-quality, regional seismic profiles that have been assembled, we have selected 10 that show excellent crustal and Pn arriv...

While the surface of Tibet is undergoing pervasive pure shear, stable terranes, straddling subsurface sutures, remain in the sub-continental lithospheric mantle (SCLM), attesting to its strength. Furthermore, sub-horizontal, cohesive remnant of Indian SCLM is traced northward from the Himalayan deformation front for about 600km, exemplifying the lo...

SUMMARYSH waveforms recorded by a dense regional seismic network are used to constrain the shear wave velocity structure of the upper-mantle transition zone beneath northeast China. By modelling triplication waveforms we show that a 130-km-thick layer of increased seismic velocities is overlying a broad slightly depressed 660 km discontinuity. This...

Using data from regional earthquakes recorded by the Hi-CLIMB array in Tibet, we model P-wave arrival times to constrain the velocity structure in the crust and the upper mantle in central and western Tibet. Of more than 30 high-quality, regional seismic profiles that have been assembled, we have selected 10 that show excellent crustal and Pn arriv...

Using data from regional earthquakes recorded by the Hi-CLIMB array in Tibet, we utilize seismic attributes from crustal and Pn arrivals to constrain the velocity and attenuation structure in the crust and the upper mantle in central and western Tibet. The seismic attributes considered include arrival times, Hilbert envelope amplitudes, and instant...

We developed a new approach of constructing deep-penetrating seismic profiles using earthquake-sources and successfully applied this technique over distances of up to 1,000 km in two geologically important regions. Along a north-south trending profile across southern and central Tibet, there are significant, regional variations in crustal thickness...

In this study, we apply Gaussian-beam (GB) migration of scattered teleseismic P waves to image the crust and upper mantle beneath Tibet using data from the Hi-CLIMB experiment. We use teleseismic P waves from three groups of earthquakes to the southeast, northeast, and northwest of the Hi-CLIMB array, each within a narrow range of azimuth and dista...

New data from west-central Tibet show that birefringence of S-waves has two pronounced increases in magnitude toward the hinterland. Null birefringence persists to about 75 km north of the Indus–Yarlung suture (IYS) between the Indian shield and the Lhasa terrane of southern Tibet. A second, rapid increase occurs about 100 km farther north of the B...

With a new multi-scale parameterization, 3-D images from finite-frequency seismic tomography, including the very first images beneath central Tibet from S-waves, reveal that regions of low electric resistivity in the crust, previously observed along active rifts in southern Tibet, correlate well with regions of low P-and S-wave speeds (V). However,...

1] A new approach of constructing deep-penetrating seismic profiles reveals significant, regional variations in crustal thickness under near-constant elevation of Tibet. Over distances of hundreds of kilometers, the crust is as thick as 75 km in southern Tibet but shoals to just over 60 km under the Qiangtang terrane in central Tibet where the devi...

We match high-resolution seismic data from Project Hi-CLIMB with new techniques to holistically address several fundamental questions regarding the most prominent case of active continental collision. Images from multi-scale, finite-frequency tomography of both P- and S-wave travel-times, and regional patterns of S-wave birefringence delineate the...

Using data from local and regional events recorded by the Hi-CLIMB array in Tibet, we utilize seismic attributes, including arrival times, Hilbert amplitudes and pulse frequencies, to constrain structures of seismic wave speed and attenuation in the crust and the upper mantle in western China. We construct more than 30 high-quality, regional seismi...

We are investigating Pn propagation in Western China based on regional events recorded by the Hi-CLIMB (An Integrated Study of the Himalayan-Tibetan Continental Lithosphere during Mountain Building) array in the region. Seismic attributes, including arrival times, Hilbert envelope amplitudes and instantaneous and spectral frequencies, are being use...

Subuction of oceanic lithosphere has been long considered as the main mechanism to carry water into the deep mantle. Regardless of whether various dehydration reactions may leave subducted slabs dry, new evidence indicates that continental collision is a viable pathway to bring water into the mantle transition zone (TZ). Using high-resolution, trip...

Traditionally, anomalies of seismic wave speeds in the deep mantle are attributed to variations in temperature alone. Lately, a variety of evidence is accumulating for petrologic causes of seismic anomalies in the mantle transition zone (TZ), including effects of kinetics, volatiles and composition. For instance, along the Tonga subduction zone, wh...

Three-dimensional seismic velocity structure of western Tibet has been resolved down to depths about 400 km from tomographic inversion of relative travel-time residuals of teleseismic P- and S-waves recorded during the Hi-CLIMB Experiment. A broad swath of high wave-speeds extends northward under much of the Lhasa terrane, passing beyond the Bangon...

In realistic models of the crust and the upper mantle where vertical gradients in wave speeds and major interfaces are present, propagation of Pn, an important seismic phase at regional distances, involves complex effects of interference. Such effects can result in wave-trains whose frequency-contents and amplitudes vary with distance in counter-in...

Using high-resolution, triplicate shear-waveforms recorded by broadband seismic arrays, we show that a corresponding anomaly of high S-wave speed (V S) is absent where an anomaly of high P-wave speed (V P) was recently recognized in the transition zone of the mantle (TZ) beneath central Tibet. A likely cause of the discrepancy between anomalies in...

The mainstay of Hi-CLIMB (An Integrated Study of the Himalayan-Tibetan Continental Lithosphere during Mountain Building) is a hybrid linear/regional seismic array that has an aperture of over 800 km by 800 km. With over 200 stations, this is by far the most extensive deployment of broadband, transportable seismic arrays to date, with a dense spacin...

We present a synthesis regarding the current configuration of Asian and Indian mantle lithosphere beneath the Himalayan-Tibetan collision zone -- the most prominent zone of active continental collision. The following cross- sectional view is achieved by combining new results from complementary approaches, including modeling profiles of triplicate w...

Deep earthquakes are always associated with zones of recent convergence where cold temperature is expected in the mantle. Since low temperatures will raise both P- and S-wave speeds ( VP and VS), aseismic anomalies of high V in the transition zone of the mantle (TZ) provide unique insights into the origin of deep seismicity: Low temperature is only...

1] Using seismic profiles comprising of high-resolution, triplicate waveforms across apertures of over 1,000 km, we show that because of high P wave speed (V P) near the bottom of the mantle transition zone, the contrast in V P across the 660-km discontinuity beneath central Tibet is small: only about 70% of that beneath the northern Indian shield....

Using high-resolution, triplicate body waveforms, I investigate P- and S-wave velocities (VP and VS) of the mantle transition zone beneath two convergent margins---the northern Philippine Sea for an oceanic subduction and the Tibetan plateau for a continent-continent collision. For the subduction case, I find correspondingly high VS in the back-arc...

A broadband, linear seismic array of over 800 km in length was deployed across the Himalayan-Tibetan collision zone as part of Project Hi-CLIMB. Overall, more than 200 seismic station locations were occupied during 2002- 2005, with an average station spacing of 3-8 km along the linear array. In this study, we use Gaussian-Beam (GB) migration of sca...

A key component of Project Hi-CLIMB (An Integrated Study of the Himalayan-Tibetan Continental Lithosphere during Mountain Building) is a broadband seismic array of over 800 kilometers in length across the Himalayan- Tibetan collision zone. Along a north-south trending corridor between 84°E and 86°E meridians, the array extended from the southern ed...

We demonstrate a case of using short-period, vertical-component seis-mograms alone to study the Archean crust. The approach is equivalent to conven-tional seismic reflection profiles except that high-frequency (up to 1.2 Hz) transmitted wave fields from earthquakes are used as natural sources. On seismic sections from the Gauribidanur Array (GBA),...

The fate of mantle lithosphere during continent-continent collision is a key question in continental dynamics. Unfortunately there were few tight constraints on mantle processes beneath the Himalayan-Tibetan orogen - the most prominent, active collision zone on the Earth. We address this issue with high-resolution seismic results concerning the nat...

The extent of slab penetration through the mantle transition zone (TZ) is a key issue in mantle convection and geochemical mixing. For the most part, both proponents and opponents of deep slab penetration have relied upon the detection of high seismic wave speeds as evidence for regions of low temperature, a proxy for subducted material. For instan...

Using triplicate waveforms, we construct 34 seismic profiles east of Taiwan to investigate lateral variations of P and S wave speeds (VP and VS) near the mantle transition zone. Data from broadband and densely spaced, short-period arrays are combined to achieve high resolution. We find correspondingly high VS in the back arc of Izu-Bonin where the...

We demonstrate a rare, successful case of using P-wavefield recorded on vertical-component seismograms alone to constrain crustal properties of the southern Indian shield. The data comprise of digital seismograms recorded by the short-period Gauribidanur Array (GBA) situated on Archean crust. The P-wavefield contains critical information, such as a...

Using triplicate waveforms and travel-times from deep earthquakes, we construct 18 seismic profiles across the Philippine and the Japan Seas to investigate lateral variations of P- and S-wave speeds (Vp and Vs) in the transition zone of the mantle. Data from broadband and densely spaced, short-period arrays are combined to achieve high resolution....

Inner core attenuation properties from two spots were examined in detail using PKIKP and PKP(BC) phases with a distance range of between 147° and 154° as recorded by both the short-period regional seismic array in Taiwan and the broad-band stations of the German Regional Seismic Network. The ray paths from the six South American events to Taiwan sa...

With a new multi-scale parameterization and advanced finite-frequency theory, we resolve 3-D variations in P - and S-wave speeds (V P and V S) in both the crust and the upper mantle beneath Tibet. The resulting V P and V S models reveal that regions of low electric resistivity, previously observed along active rifts in southern Tibet, correlate wel...