Stress Drop Variations in the Region of the 2014 MW8.1 Iquique Earthquake, Northern Chile

Folesky, Jonas; Kummerow, J.; Shapiro, Serge A.

doi:10.1029/2020jb020112

Cited by 9 publications

(16 citation statements)

References 67 publications

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“…This behavior has already been described in Folesky et al. (2021) for the Iquique event. There, the variability was attributed to the increased moment rates during the immediate post‐seismic interval.…”

Section: Resultssupporting

confidence: 77%

“…In this study, similar to Folesky et al. (2021), we observe a clear dependence of stress drop on moment (Figure 12a), which contradicts the invariance hypothesis of stress drop scaling for our data set in northern Chile. We fit a linear relation (log 10 (Δ σ ) = ɛ 0 + ɛ 1 log 10 ( M 0 )) to stress drop estimates over separate magnitude bins (e.g., Trugman & Shearer, 2017) and we obtain 0.4 < ɛ 1 < 1.09.…”

Section: Discussionsupporting

confidence: 68%

“…As reported in Folesky et al. (2021) more restrictive quality criteria for spectra included in the analysis may moderately decrease the ɛ 1 parameter, but the clear positive dependence remains.…”

Section: Discussionmentioning

confidence: 61%

“…For the spectral ratio approach, we use the processing scheme described in detail in Folesky et al. (2021), where a limited region around the 2014 Mw8.1 Iquique earthquake was already investigated.…”

Section: Methodsmentioning

confidence: 99%

“…We use the regional velocity model by Bloch et al (2014) to compute event location-specific shear wave velocities. We use a k-value of k p = 0.32 for P-wave spectra, a standard value from Madariaga (1976), and we obtain k s = 0.265 by a least square fit of corner frequencies from both P and S phases for identical events, similar to Folesky et al (2021).…”

Section: Source Model and Stress Dropmentioning

confidence: 99%

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A Comprehensive Stress Drop Map From Trench to Depth in the Northern Chilean Subduction Zone

Folesky,

Pennington,

Kummerow

et al. 2024

JGR Solid Earth

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We compute stress drops for earthquakes in Northern Chile recorded between 2007 and 2021. By applying two analysis techniques, (a) the spectral ratio (SR) method and (b) the spectral decomposition (SDC) method, a stress drop map for the subduction zone consisting of 51,510 stress drop values is produced. We build an extended set of empirical Green’s functions (EGF) for the SR method by systematic template matching. Outputs are used to compare with results from the SDC approach, where we apply cell‐wise obtained global EGF's to compensate for the structural heterogeneity of the subduction zone. We find a good consistency of results of the two methods. The increased spatial coverage and quantity of stress drop estimates from the SDC method facilitate a consistent stress drop mapping of the different seismotectonic domains. Albeit only small differences of median stress drop, strike‐perpendicular depth sections clearly reveal systematic variations, with earthquakes at different seismotectonic locations exhibiting distinct values. In particular, interface seismicity is characterized by the lowest observed median value, whereas upper plate earthquakes show noticeably higher stress drop values. Intermediate depth earthquakes show comparatively high average stress drop and a rather strong depth‐dependent increase of median stress drop. Additionally, we observe spatio‐temporal variability of stress drops related to the occurrence of the two megathrust earthquakes in the study region. The presented study is the first coherent large scale 3D stress drop mapping of the Northern Chilean subduction zone. It provides an important component for further detailed analysis of the physics of earthquake ruptures.

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Section: Resultssupporting

confidence: 77%

Section: Discussionsupporting

confidence: 68%

Section: Discussionmentioning

confidence: 61%

Section: Methodsmentioning

confidence: 99%

Section: Source Model and Stress Dropmentioning

confidence: 99%

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A Comprehensive Stress Drop Map From Trench to Depth in the Northern Chilean Subduction Zone

Folesky,

Pennington,

Kummerow

et al. 2024

JGR Solid Earth

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Resolving Differences in the Rupture Properties of Prominent Earthquakes in Southern California with Bayesian Source Spectral Analysis

Trugman

2022

Preprint

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The spectra of earthquake waveforms can provide important insight into rupture processes, but the analysis and interpretation of these spectra is rarely straightforward. Here we develop a Bayesian framework that embraces the inherent data and modeling uncertainties of spectral analysis to infer key source properties. The method uses a spectral ratio approach to correct the observed waveform spectra of nearby earthquakes for path and site attenuation. The objective then is to solve for a joint posterior probability distribution of three source parameters -seismic moment, corner frequency, and high-frequency falloff rate -for each earthquake in the sequence, as well as a measure of rupture directivity for target events with good azimuthal station coverage. While computationally intensive, this technique provides a quantitative understanding of parameter tradeoffs and uncertainties and allows one to impose physical constraints through prior distributions on all source parameters, which guide the inversion when data is limited. We demonstrate the method by analyzing in detail the source properties of 14 different target events of magnitude M5 in southern California that span a wide range of tectonic regimes and fault systems. These prominent earthquakes, while comparable in size, exhibit marked diversity in their source properties and directivity, with clear spatial patterns, depth-dependent trends, and a preference for unilateral directivity. These coherent spatial variations source properties suggest that regional differences in tectonic setting, hypocentral depth or fault zone characteristics may drive variability in rupture processes, with important implications for our understanding of earthquake physics and its relation to hazard.

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Resolving Differences in the Rupture Properties of M5 Earthquakes in California Using Bayesian Source Spectral Analysis

Trugman

2022

JGR Solid Earth

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Stress Drop Variations in the Region of the 2014 M_W8.1 Iquique Earthquake, Northern Chile

Cited by 9 publications

References 67 publications

A Comprehensive Stress Drop Map From Trench to Depth in the Northern Chilean Subduction Zone

A Comprehensive Stress Drop Map From Trench to Depth in the Northern Chilean Subduction Zone

Resolving Differences in the Rupture Properties of Prominent Earthquakes in Southern California with Bayesian Source Spectral Analysis

Resolving Differences in the Rupture Properties of M5 Earthquakes in California Using Bayesian Source Spectral Analysis

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