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Gary L. Pavlis

Publications and source records attributed to Gary L. Pavlis.

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Evaluating PhaseNet on Teleseismic Data with MsPASS

Numerous studies have shown that the machine-learning picker PhaseNet produces accurate P and S picks on local earthquake signals, but its performance can degrade sharply on teleseismic signals. To address this limitation, we present a reproducible MsPASS workflow that (i) enables scalable data preparation and management for large seismic archives and (ii) supports standardized PhaseNet training and inference. We assembled a control dataset of 1.6 million waveforms linked to teleseismic P-wave picks made by analysts at the USArray Array Network Facility (ANF). The control dataset confirms that the PhaseNet model trained on regional signals performs poorly on these data. We then trained PhaseNet from scratch on the training split of the ANF control dataset and evaluated it on a non-overlapping held-out test split, increasing P-pick recall by 741.5% and yielding 683.9% more picks within a 0.1s residual window. We also evaluated PhaseNet across different model sizes on both CPUs and GPUs. Increasing the model size by about 120 times improved precision and recall by 15.6% and 23.2%, respectively. However, the scaled model reduced inference throughput by 87.2% on an NVIDIA A100 GPU and by 97.3% on a 128-core high-performance CPU node. These results indicate that scaling PhaseNet is more practical on GPUs than on CPUs, and that simply enlarging the model is not an efficient way to achieve large accuracy gains.

physics.geo-ph

Parallel Seismic Data Processing Performance with Cloud-based Storage

This article introduces a general processing framework to effectively utilize waveform data stored on modern cloud platforms. The focus is hybrid processing schemes where a local system drives processing. We show that downloading files and doing all processing locally is problematic even when the local system is a high-performance compute cluster. Benchmark tests with parallel processing show that approach always creates a bottleneck as the volume of data being handled increases with more processes pulling data. We find a hybrid model where processing to reduce the volume of data transferred from the cloud servers to the local system can dramatically improve processing time. Tests implemented with Massively Parallel Analysis System for Seismology (MsPASS) utilizing Amazon Web Service's Lamba service yield throughput comparable to processing day files on a local HPC file system. Given the ongoing migration of seismology data to cloud storage, our results show doing some or all processing on the cloud will be essential for any processing involving large volumes of data.

physics.geo-ph

Multiscale Roughness of Upper Mantle Discontinuities Inferred from the USArray: Dependence on Tomography Models

We used 3D plane wave migration to image topography of the upper mantle discontinuities at 410 km and 660 km depth that defines the transition zone. We find both discontinuities have topography variation at all resolvable scales. In this paper we examine the dependency of discontinuity roughness on tomography models. We migrated a common USArray data set with a selection of regional, global, surface wave, and body wave tomography models to distinguish different scales of roughness. The objective is to appraise what features are potential artifact from using an inaccurate velocity model. We find that the largest-scale features depend on the choice of tomography model, while smaller-scale features appear to be almost completely independent of current generation models. We suggest that this observation is additional evidence of the existence of small-scale roughness on the upper mantle discontinuities not captured with the data sampling density of the USArray. We find all models based only on body wave travel times alone do not remove a continent scale offset of both discontinuities that correlates with the edge of the craton. We conclude that offset is an artifact linked to underestimation of wave speed in the upper mantle by pure body wave models. Models produced by joint inversion with surface wave dispersion data are less prone to this apparent artifact. The large-scale topography variation is consistent with rigid plate motion models of the subducted Farallon slab underneath North American. Smaller scale topography is found to have larger variation in regions where the vertical mantle flow through the transition zone is implied by transition zone thickness.

physics.geo-ph