Directivity Modes of Earthquake Populations with Unsupervised Learning

Ross, Zachary E.; Trugman, Daniel T.; Azizzadenesheli, Kamyar; Anandkumar, Anima

doi:10.1029/2019jb018299

Cited by 21 publications

(11 citation statements)

References 54 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…[73,168,190]), but for statistical analysis and ground motion prediction larger scale inversion of greater numbers of events is essential. Combining and developing the large scale inversion methods of Shearer et al [119] and Ross et al [191] with improved statistical analysis of the uncertainties and biases caused by simplifying assumptions and methods (e.g. [130,192,193]) is proving fruitful.…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Resolution and uncertainties in estimates of earthquake stress drop and energy release

Abercrombie

2021

Phil. Trans. R. Soc. A.

100

View full text Add to dashboard Cite

Our models and understanding of the dynamics of earthquake rupture are based largely on estimates of earthquake source parameters, such as stress drop and radiated seismic energy. Unfortunately, the measurements, especially those of small and moderate-sized earthquakes (magnitude less than about 5 or 6), are not well resolved, containing significant random and potentially systematic uncertainties. The aim of this review is to provide a context in which to understand the challenges involved in estimating these measurements, and to assess the quality and reliability of reported measurements of earthquake source parameters. I also discuss some of the ways progress is being made towards more reliable parameter measurements. At present, whether the earthquake source is entirely self-similar, or not, and which factors and processes control the physics of the rupture remains, at least in the author's opinion, largely unconstrained. Detailed analysis of the best recorded earthquakes, using the increasing quantity and quality of data available, and methods less dependent on simplistic source models is one approach that may help provide better constraints. This article is part of the theme issue ‘Fracture dynamics of solid materials: from particles to the globe’.

show abstract

Section: Discussionmentioning

confidence: 99%

“…[119] and Ross et al . [191] with improved statistical analysis of the uncertainties and biases caused by simplifying assumptions and methods (e.g. [130,192,193]) is proving fruitful.…”

Section: Discussionmentioning

confidence: 99%

Resolution and uncertainties in estimates of earthquake stress drop and energy release

Abercrombie

2021

Phil. Trans. R. Soc. A.

100

View full text Add to dashboard Cite

show abstract

“…In particular, the directivity pattern caused by the updip propagation is become evident only around the surface exposure or around its updip projection (Somerville 2003). These updip effects, without stations right on top of the rupture (as AMT station) are very difficult to be observed (Ross et al 2020). However, in Fig.…”

Section: Spatial Distribution Of Ground Motion From Hybrid Broad-band...mentioning

confidence: 95%

Broad-band ground-motion simulation of 2016 Amatrice earthquake, Central Italy

Pischiutta

Akinci

Tinti

et al. 2020

Geophysical Journal International

View full text Add to dashboard Cite

Summary On 24th August 2016 at 01:36 UTC a ML6.0 earthquake struck several villages in central Italy, among which Accumoli, Amatrice and Arquata del Tronto. The earthquake was recorded by about 350 seismic stations, causing 299 fatalities and damage with macroseismic intensities up to 11. The maximum acceleration was observed at Amatrice station (AMT) reaching 916 cm/s2 on E-W component, with epicentral distance of 15 km and Joyner and Boore distance to the fault surface (RJB) of less than a kilometre. Motivated by the high levels of observed ground motion and damage, we generate broadband seismograms for engineering purposes by adopting a hybrid method. To infer the low frequency seismograms, we considered the kinematic slip model by Tinti et al. (2016). The high frequency seismograms were produced using a stochastic finite-fault model approach based on dynamic corner-frequency. Broadband synthetic time series were therefore obtained by merging the low and high frequency seismograms. Simulated hybrid ground motions were compared both with the observed ground motions and the ground-motion prediction equations (GMPEs), to explore their performance and to retrieve the region-specific parameters endorsed for the simulations. In the near-fault area we observed that hybrid simulations have a higher capability to detect near source effects and to reproduce the source complexity than the use of GMPEs. Indeed, the general good consistency found between synthetic and observed ground motion (both in the time and frequency domain), suggests that the use of regional-specific source scaling and attenuation parameters together with the source complexity in hybrid simulations improves ground motion estimations. To include the site effect in stochastic simulations at selected stations, we tested the use of amplification curves derived from HVRSs (horizontal-to-vertical response spectra) and from HVSRs (horizontal-to-vertical spectral ratios) rather than the use of generic curves according to NTC-18 Italian seismic design code. We generally found a further reduction of residuals between observed and simulated both in terms of time histories and spectra.

show abstract

“…Earthquake ruptures can be classified in pure unilateral or pure bilateral (symmetric) ruptures, as well as asymmetric bilateral ruptures, describing an intermediate case between the two previous models. It is well know that a predominance of unilateral ruptures is observed for large earthquakes (McGuire et al, 2002); however, recent studies demonstrated that directivity might be also a common feature of small to moderate events (e.g., Kane et al, 2013;Kurzon et al, 2014;Calderoni et al, 2015;Meng et al, 2020;Ross et al, 2020). So far, rupture directivity has also been identified for a few cases of weak fluid-injection induced earthquakes (Folesky et al, 2016;López-Comino and Cesca, 2018;Király Proag et al, 2019;Wu et al, 2019) and fluid-induced microcracks or acoustic emission (AE) events in mine-scale hydraulic fracturing (HF) experiments (Dahm, 2001), suggesting that such properties could persist at smaller magnitudes.…”

Section: Introductionmentioning

confidence: 99%

Rupture Directivity in 3D Inferred From Acoustic Emissions Events in a Mine-Scale Hydraulic Fracturing Experiment

et al. 2021

View full text Add to dashboard Cite

Rupture directivity, implying a predominant earthquake rupture propagation direction, is typically inferred upon the identification of 2D azimuthal patterns of seismic observations for weak to large earthquakes using surface-monitoring networks. However, the recent increase of 3D monitoring networks deployed in the shallow subsurface and underground laboratories toward the monitoring of microseismicity allows to extend the directivity analysis to 3D modeling, beyond the usual range of magnitudes. The high-quality full waveforms recorded for the largest, decimeter-scale acoustic emission (AE) events during a meter-scale hydraulic fracturing experiment in granites at ∼410 m depth allow us to resolve the apparent durations observed at each AE sensor to analyze 3D-directivity effects. Unilateral and (asymmetric) bilateral ruptures are then characterized by the introduction of a parameter κ, representing the angle between the directivity vector and the station vector. While the cloud of AE activity indicates the planes of the hydrofractures, the resolved directivity vectors show off-plane orientations, indicating that rupture planes of microfractures on a scale of centimeters have different geometries. Our results reveal a general alignment of the rupture directivity with the orientation of the minimum horizontal stress, implying that not only the slip direction but also the fracture growth produced by the fluid injections is controlled by the local stress conditions.

show abstract

Directivity Modes of Earthquake Populations with Unsupervised Learning

Cited by 21 publications

References 54 publications

Resolution and uncertainties in estimates of earthquake stress drop and energy release

Resolution and uncertainties in estimates of earthquake stress drop and energy release

Broad-band ground-motion simulation of 2016 Amatrice earthquake, Central Italy

Rupture Directivity in 3D Inferred From Acoustic Emissions Events in a Mine-Scale Hydraulic Fracturing Experiment

Contact Info

Product

Resources

About