Geology topics

Dino Bindi

Publications and source records attributed to Dino Bindi.

3 recordsLinked to original sources

USGS2025

Overview of The SCEC/USGS Community Stress Drop Validation Study using the 2019 Ridgecrest earthquake sequence

We present initial findings from the ongoing Community Stress Drop Validation Study to compare spectral stress‐drop estimates for earthquakes in the 2019 Ridgecrest, California, sequence. This study uses a unified dataset to independently estimate earthquake source parameters through various methods. Stress drop, which denotes the change in average shear stress along a fault during earthquake rupture, is a critical parameter in earthquake science, impacting ground motion, rupture simulation, and source physics. Spectral stress drop is commonly derived by fitting the amplitude‐spectrum shape, but estimates can vary substantially across studies for individual earthquakes. Sponsored jointly by the U.S. Geological Survey and the Statewide (previously, Southern) California Earthquake Center our community study aims to elucidate sources of variability and uncertainty in earthquake spectral stress‐drop estimates through quantitative comparison of submitted results from independent analyses. The dataset includes nearly 13,000 earthquakes ranging from M 1 to 7 during a two‐week period of the 2019 Ridgecrest sequence, recorded within a 1° radius. In this article, we report on 56 unique submissions received from 20 different groups, detailing spectral corner frequencies (or source durations), moment magnitudes, and estimated spectral stress drops. Methods employed encompass spectral ratio analysis, spectral decomposition and inversion, finite‐fault modeling, ground‐motion‐based approaches, and combined methods. Initial analysis reveals significant scatter across submitted spectral stress drops spanning over six orders of magnitude. However, we can identify between‐method trends and offsets within the data to mitigate this variability. Averaging submissions for a prioritized subset of 56 events shows reduced variability of spectral stress drop, indicating overall consistency in recovered spectral stress‐drop values.

California↗

USGS2024

SCEC/USGS Community Stress Drop Validation Study: How spectral fitting approaches influence measured source parameters

Spectral source parameters used to estimate an earthquake’s stress drop (Δσ) can vary significantly across measurement approaches. The Statewide California Earthquake Center/U.S. Geological Survey Community Stress-Drop Validation Study was initiated to compare source parameter estimates, focusing initially on a dataset from the 2019 Ridgecrest earthquake sequence. As part of that validation effort, here we focus on one potential source of uncertainty: whether spectral fitting approaches alone, applied to a common set of spectra from the 2019 Ridgecrest sequence result in different source parameter estimates. By using a common set of benchmark spectra analyzed across a consistent frequency band of 1–40 Hz, we eliminate many sources of variability. A subgroup of validation study participants volunteered to estimate the low-frequency displacement (Ω0) and corner frequency ( f c ) by fitting a smooth function to benchmark displacement spectra. Participants used linear- or log-sampled spectra, assumed a Brune or Boatwright spectral model, and applied different misfit criteria. We compare 17 approaches used to estimate Ω0, f c , and Δσ for 54 earthquake spectra. Our results reveal that 35% of events have Δσ estimates within a factor of two, whereas others exhibit variations exceeding an order of magnitude. The variability in Ω0 and f c can largely be attributed to whether a spectrum is consistent with the smooth function of an idealized simple crack model. The trade-off between Ω0 and f c may be more pronounced when using linearly sampled spectra, as higher frequency spectral bumps control the fits. As expected, methods that assumed a Boatwright model tended to have lower Ω0 and somewhat higher f c compared to those assuming a Brune model, although resulting Δσ estimates are similar. When compared to the overall validation study results, the fitting approach alone may account for between 5% and 90% (25% on average) of the total variability in spectral Δσ.

California↗

USGS2021

Regional calibration of hybrid ground‐motion simulations in moderate seismicity areas: Application to the Upper Rhine Graben

This study presents the coupling of the spectral decomposition results for anelastic attenuation, stress drop, and site effects with the Graves‐Pitarka (GP) hybrid ground‐motion simulation methodology, as implemented on the Southern California Earthquake Center (SCEC) broadband platform (BBP). It is targeted to applications in the Upper Rhine graben (URG), which is among the seismically active areas in western Europe, yet a moderate seismicity area. Our development consists of three main steps: (1) calibration of regional high‐frequency (HF) attenuation properties; (2) modification of the hybrid approach to add compressional waves in the HF computation and examine various strategies to evaluate site amplification factors in the Fourier domain (e.g., V S 30 "> V S 30 VS30 ‐based or site‐specific factors); (3) testing of the simulations using earthquake records from the URG ( ⁠ 3.7 < M w < 5 "> 3.7 < M w < 5 3.7<Mw<5 ⁠ ). The validation process of the simulated time histories is performed first on rock sites, and, then subsequently at all stations, whatever their site conditions. The performance of the simulations for rock sites is assessed through the standard validation technique in the BBP (comparison of the waveforms, intensity measures, and estimation of the response spectra model bias). We additionally compare the Fourier amplitude spectrum of the simulations and observations, and compute their corresponding bias. The results show that the simulated ground motions match the general characteristics of the recorded motions, and that the model bias generally fluctuates around zero across the broadband frequency range. Hence, the hybrid ground‐motion methodology implemented in the SCEC BBP can be successfully applied outside high‐seismicity areas and outside those areas for which it had been generally calibrated. Our results also show that HF modification and calibration were necessary to improve the fits with the observation, and demonstrate the potential benefits of using site‐specific amplification factors compared to V S 30 "> V S 30 VS30 ‐based amplification factors.

Upper Rhine Graben↗