Scaling Relationships of Source Parameters of Inland Crustal Earthquakes in Tectonically Active Regions

Miyakoshi, Ken; Somei, Kazuhiro; Yoshida, Kunikazu; Kurahashi, Susumu; Irikura, Kojiro; Kamae, Katsuhiro

doi:10.1007/s00024-019-02160-0

Cited by 17 publications

(14 citation statements)

References 20 publications

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“…Our analysis reveals that potency density is independent of rupture size, considering ruptures of the same type and tectonic setting, consistent with seismological studies of stress drop (Allmann & Shearer, 2009; Kanamori & Anderson, 1975; Miyakoshi et al, 2019; Venkataraman & Kanamori, 2004; Ye et al, 2016b). The independence of potency density with size for ruptures of any type is compatible with the idea that stress drop or potency density is a fundamental property of ruptures leading to self‐similarity of the earthquake phenomenon (Cocco et al, 2016).…”

Section: Discussionsupporting

confidence: 87%

Static Source Properties of Slow and Fast Earthquakes

2020

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The source characteristics of slow and fast earthquakes provide a window into the mechanical properties of faults. In particular, the average stress drop controls the evolution of friction, fault slip, and event magnitude. However, this important source property is typically inferred from the analysis of seismic waves and is subject to many epistemic uncertainties. Here, we investigate the source properties of 53 earthquakes and 17 slow-slip events on thrust and strike-slip faults in various tectonic settings using slip distributions constrained by geodesy in combination with other data. We determine the width, potency, and potency density of slow and fast earthquake sources based on static slip distributions. The potency density, defined conceptually as the ratio of average slip to rupture radius, is a measure of anelastic deformation with limited bias from rigidity differences across depths and tectonic settings. Strike-slip earthquakes have the highest potency density, varying from 20 to 500 microstrain. The potency density is on average lower on continental thrust faults and megathrusts, from 10 to 200 microstrain, with an algebraic decrease with centroid depth, indicative of systematic changes in dominant rupture processes with depth. Slow slip events represent an end-member style of rupture with low potency density and large rupture width. Significant variability in potency density of slow-slip events affects their moment-duration scaling. The variations of source properties across tectonic settings, depth, and rupture styles can be used to better constrain numerical simulations of seismicity and to assess the source characteristics of future earthquakes and slow slip events. Plain Language Summary Natural earthquakes reduce the stress that accumulates on faults due to plate tectonics. To better understand the variability of seismic hazards around active faults, we survey the properties of slow and fast earthquakes around the world. The potential of faults to concentrate large slip in the rupture area differs depending on the geological setting, the depth of the source, and the type of rupture. Earthquakes in a continental setting condense more slip in a given rupture area, particularly in transform faults like the San Andreas fault. Subduction zone earthquakes, although some of the largest events on Earth, generally distribute less slip over a wider area, but this varies as a function of depth. Slow earthquakes represent an extreme case of little slip distributed over a large area. The propensity of rupture characteristics to vary with fault type and depth may help forecast the hazards posed by future seismicity.

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Section: Discussionsupporting

confidence: 87%

Static Source Properties of Slow and Fast Earthquakes

2020

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“…As it is a difficult issue to choose the appropriate area for the Δσ E calculation (Brown et al, 2015), we also calculate the stress drop using all subfaults and the subfaults with D > 0.5 × D max (the region marked by green lines in Figure 4a), and we obtain Δσ E = 3.3 MPa and Δσ E = 6.8 MPa, respectively. This value seems not so small as expected for the interplate earthquakes (∼10 0 MPa, e.g., Kanamori & Anderson, 1975), but rather is consistent with the intraplate earthquakes, which generally have larger stress drop values (e.g., Miyakoshi et al, 2020;Somerville et al, 1999).…”

Section: Stress Dropsupporting

confidence: 79%

“…Considering this range, the estimated fault dimensions are obviously smaller than expected based on the scaling relation. These much smaller fault dimensions are consistent with the size of the asperity, defined as the region of the large slip on the fault (e.g., Somerville et al, 1999), expected from the empirical relation deduced from the inland crustal earthquakes (Miyakoshi et al, 2020;Somerville et al, 1999). This may suggest that this optimum rectangular fault corresponds to the asperity.…”

Section: Rectangular Fault Model With Uniform Slipmentioning

confidence: 99%

Improving the Constraint on theM_w7.1 2016 Off‐Fukushima Shallow Normal‐Faulting Earthquake With the High Azimuthal Coverage Tsunami Data From the S‐Net Wide and Dense Network: Implication for the Stress Regime in the Tohoku Overriding Plate

et al. 2021

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“…4). The stress drops recently obtained by Miyakoshi et al (2020) are also plotted in Figure 4, again showcasing the systematic tendency of larger stress drops for the Iranian earthquakes, although the values estimated by Miyakoshi et al (2020) were obtained via seismic waveform inversion analyses, which can lead to different results (which was the case for the 2014 Nagano earthquake). Manighetti et al (2007) pointed out that the earthquake stress drop has a strong relationship with the structural maturity of the ruptured fault.…”

Section: High Stress Drops Of the Iranian Earthquakesmentioning

confidence: 74%

“…(2) A larger stress drop leads to the radiation of strong short-period ground motions. The stress drop is a key parameter for the estimation of strong ground motions caused by earthquake ruptures (e.g., Miyakoshi et al 2020;Soghrat et al 2012). We compared the stress drops of the studied Iranian earthquakes with those of the Japanese earthquakes obtained from our earlier study (Ghayournajarkar and Fukushima 2022) and other studies.…”

Section: Analysis and Results Of Fault Parameter Estimationmentioning

confidence: 99%

InSAR-Derived Source Characteristics of Iranian Blind Reverse-Fault Earthquakes and Their Implications for Seismic Hazard Evaluation

Ghayournajarkar

Fukushima

Nakahara

2022

Preprint

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Investigating fault characteristics is necessary for seismic hazard evaluation and can provide useful insights for municipalities to optimize their investments in safer buildings and more resilient infrastructure. The location and the geometry of the faults, especially their relationship with sedimentary layer thickness, and the amount of stress drop are critical components when evaluating strong ground motions caused by earthquakes. Interferometric Synthetic Aperture Radar (InSAR) is a powerful tool for accurately determining fault parameters of shallow inland earthquakes and investigating their characteristics in terms of seismic hazards. In this study, based on our earlier results from InSAR data inversions conducted on five Iranian shallow blind reverse-fault earthquakes, we particularly exploited the resolving power of InSAR to investigate fault characteristics and discussed their implications for seismic hazard evaluation in Iran. For all studied Iranian earthquakes, the InSAR-derived fault was deeper than the sedimentary layer. This may indicate that these earthquakes did not rupture the entire seismogenic layer, likely leaving a significant seismic potential. Moreover, the average stress drop of the Iranian earthquakes was relatively large (13.4 MPa), which might be related to their immature blind reverse faults, leading to a possibility of generating stronger short-period ground motions, which should receive greater consideration in future seismic hazard analyses. As InSAR data can be easily accessed, this study presents a cost-effective method to provide fault parameters that can be used for the evaluation of strong ground motions caused by earthquakes, even in countries where observation networks of strong ground motions are not well developed.

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Scaling Relationships of Source Parameters of Inland Crustal Earthquakes in Tectonically Active Regions

Cited by 17 publications

References 20 publications

Static Source Properties of Slow and Fast Earthquakes

Static Source Properties of Slow and Fast Earthquakes

Improving the Constraint on theM_w7.1 2016 Off‐Fukushima Shallow Normal‐Faulting Earthquake With the High Azimuthal Coverage Tsunami Data From the S‐Net Wide and Dense Network: Implication for the Stress Regime in the Tohoku Overriding Plate

InSAR-Derived Source Characteristics of Iranian Blind Reverse-Fault Earthquakes and Their Implications for Seismic Hazard Evaluation

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Scaling Relationships of Source Parameters of Inland Crustal Earthquakes in Tectonically Active Regions

Cited by 17 publications

References 20 publications

Static Source Properties of Slow and Fast Earthquakes

Static Source Properties of Slow and Fast Earthquakes

Improving the Constraint on theMw7.1 2016 Off‐Fukushima Shallow Normal‐Faulting Earthquake With the High Azimuthal Coverage Tsunami Data From the S‐Net Wide and Dense Network: Implication for the Stress Regime in the Tohoku Overriding Plate

InSAR-Derived Source Characteristics of Iranian Blind Reverse-Fault Earthquakes and Their Implications for Seismic Hazard Evaluation

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Improving the Constraint on theM_w7.1 2016 Off‐Fukushima Shallow Normal‐Faulting Earthquake With the High Azimuthal Coverage Tsunami Data From the S‐Net Wide and Dense Network: Implication for the Stress Regime in the Tohoku Overriding Plate