Using the spectral-element method, we explored effect of topography upper-mantle discontinuities on traveltimes SS precursors recorded transverse component seismograms. The latter are routinely used to infer mantle transition zone discontinuities. step from precursory topographic changes is mainly done using linearised ray theory, or sometimes finite-frequency kernels. We simulated exact seismograms in 1-D and 3-D elastic models mantle. In a second simulation, added compared waveforms...

Distributed Acoustic Sensing (DAS) has become a popular method of observing seismic wavefields: backscattered pulses light reveal strains or strain-rates at any location along fiber-optic cable. In contrast, few newer systems transmit through cable and collect integrated phase delays over the entire cable, such as Microwave Frequency Fiber Interferometer (MFFI). These can be deployed significantly longer distances, may used in conjunction with live telecommunications, cheaper. However, they...

SUMMARY We present a novel approach for imaging global mantle discontinuities based on full-waveform inversion (FWI). Over the past decades, extensive research has been done at approximately 400 and 670 km depth. Accurate knowledge of their topography can put strong constraints thermal compositional variations hence geodynamic modelling. So far, however, there is little consensus topography. an adjoint tomography, which advantage that Fréchet derivatives measurements, to be inverted for, are...

Using spectral-element simulations of wave propagation, we investigated the sensitivity seismic waveforms, recorded on transverse components, to upper-mantle discontinuities in 1-D and 3-D background models. These kernels, or Fréchet derivatives, illustrate spatial model parameters, which those for shear speed surface topography internal boundaries are discussed this paper. We focus at 400 670 km depth mantle transition zone. SS precursors have frequently been used infer discontinuities....

We analyze the sensitivity of PP precursor traveltimes that are often used to infer lateral variation in depths 410- and 660-km discontinuities mantle. Previous results were inconclusive due complex wave phenomena, such as multiple energy conversions focusing/defocusing, hamper their interpretation. Using spectral-element synthetics Fréchet derivatives calculated with adjoint methods, we compute kernels for volumetric boundary parameters a 1-D model representative epicentral distances past...

SUMMARY The method of ScS reverberation migration is based on a ‘common reflection point’ analysis multiple reflections in the mantle transition zone (MTZ). We examine whether ray-theoretical traveltimes, slownesses and points are sufficiently accurate for estimating thickness H MTZ, defined by distance between 410- 660-km phase transitions. First, we analyse reverberations generated 35 earthquakes recorded at hundreds seismic stations from combined Arrays China, Hi-NET Japan Global Seismic...

Using spectral-element and adjoint methods, we investigate body waves interacting with the Earth's most dramatic interface, core-mantle boundary (CMB). Intermediate-to-high frequency seismograms are computed incorporating topography models. We analyse sensitivity of many seismic phases interface. The study aims at showing effects CMB structure on synthetics highlights difficulties imaging this region due to strong trade-off between velocity variations topography. Synthetic waveforms dominant...

The level of earthquake motion observed on the ground surface differs from shaking at locations buried a depth. Characterization underground is important for local seismic hazard assessment depth which an insufficiently investigated topic so far. Advancements in prediction are especially design deep geological disposals nuclear waste, buildings with foundations, or studies focused soil-structure interactions. In this paper, we analyze site-specific transfer functions that relate motions to...

Abstract. According to 2018 demographic data of the American Geophysical Union Fall Meeting, seismology is among geoscience fields with lowest representation women. To understand whether this reflects more generally, we investigate women's authorship peer-reviewed publications, a key factor in career advancement. Building upon open-source tools for web-scraping, create database bibliographic information seismological articles published 14 international journals from 2010 2020. We use...

Abstract The SS precursors have been extensively utilized in mapping the mantle transition zone (MTZ). However, their applications are often challenged by weak phases that arise from small impedance contrasts of discontinuities, noise contamination, and localized thermal/compositional heterogeneities. We develop a new data processing workflow for more reliable MTZ imaging adopting recently proposed robust damped rank‐reduction (RDRR) method exploration seismology. This exploits signal...

Accurate prediction and synthesis of seismic waveforms are crucial for hazard assessment earthquake-resistant infrastructure design. Existing methods, such as Ground Motion Models physics-based simulations, often fail to capture the full complexity wavefields, particularly at higher frequencies. This study introduces a novel, efficient, scalable generative model high-frequency waveform generation. Our approach leverages spectrogram representation data, which is reduced lower-dimensional...

We analyze the sensitivity of PP precursor traveltimes that are often used to infer lateral variation in depths 410- and 660-km discontinuities mantle. Previous results were inconclusive due complex wave phenomena, such as multiple energy conversions focusing/defocusing, hamper their interpretation. Using spectral-element synthetics Frechet derivatives calculated with adjoint methods, we compute kernels for volumetric boundary parameters a 1-D model representative epicentral distances past...

<div>This study presents a new approach for investigating the structure of core-mantle boundary (CMB)</div><div>topography based on full-waveforms and adjoint methods. We compute intermediate period (10-20 seconds)</div><div>spectral-element seismograms using existing models topography we analyse the</div><div>sensitivity relevant seismic phases. Our adds information about effects CMB...

<p>In this study, we develop a new adjoint- and full-waveform inversion approach for low-amplitude seismic phases that are typically below noise in individual recordings. The methodology aims at enhancing weak signals from body wave phases, which can be used inferring structural boundary parameters the earth. is based on formulation of misfit functionals corresponding adjoint sources stacks suitably time-shifted recordings. </p><p>To...