Uncertainty estimations for moment tensor inversions: the issue of the 2012 May 20 Emilia earthquake

Scognamiglio, Laura; Magnoni, Federica; Tinti, Elisa; Casarotti, Emanuele

doi:10.1093/gji/ggw173

Cited by 22 publications

(30 citation statements)

References 32 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Dislocation modeling revealed that two main shocks ruptured two distinct segments of the Ferrara arc (Figure ). The 20 May M w 6.1 main shock occurred on a ∼45° S‐SW dipping, ∼15 km long thrust fault, with a main patch of slip located at the center of the plane, corresponding to the Middle Ferrara thrust, in good agreement with previous inversions of geodetic data [e.g., Pezzo et al , ], moment tensor solutions [e.g., Scognamiglio et al , ], and relocated aftershocks [e.g., Chiarabba et al , ].…”

Section: Discussionsupporting

confidence: 85%

“…Thus, our 29 May coseismic joint model (Figure b) will contain a small amount of postseismic slip as well as the second main shock coseismic slip. Our moment release results are in agreement with the range of seismic moment estimates of the two main shocks published so far [ Pondrelli et al , ; Scognamiglio et al , ; Pezzo et al , ; Chiarabba et al , ; Govoni et al , ; Carannante et al , ; Scognamiglio et al , ].…”

Section: Inversion Of Geodetic Datasupporting

confidence: 91%

“…Seismological, geodetic, and geological‐based studies published so far have not clarified the exact association between activated thrust segment and related main shock nor the fine details of the geometry of the activated fault systems during the Emilia seismic sequence. For the fault geometry of the rupture segment responsible for the 20 May M w 6.1 main shock, inversion of geodetic data, moment tensor solutions, precise aftershock relocations, and interpretation of deep seismic reflection data all indicate an approximately 100°N striking, thrust fault dipping ∼45 ∘ to S‐SW [ Bignami et al , ; Malagnini et al , ; Pondrelli et al , ; Scognamiglio et al , ; Serpelloni et al , ; Pezzo et al , ; Chiarabba et al , ; Govoni et al , ; Carannante et al , ; Scognamiglio et al , ] whose surface projection corresponds to the middle segment of the Ferrara Thrust System (MF in Figure ). Hypocentral locations and aftershock relocations do not support a rupture scenario with slip on the innermost thrust (IF in Figure ) as proposed by Tizzani et al [].…”

Section: The 2012 Emilia Earthquake Sequencementioning

confidence: 99%

See 2 more Smart Citations

New insights into fault activation and stress transfer between en echelon thrusts: The 2012 Emilia, Northern Italy, earthquake sequence

et al. 2016

View full text Add to dashboard Cite

Here we present the results of the inversion of a new geodetic data set covering the 2012 Emilia seismic sequence and the following 1 year of postseismic deformation. Modeling of the geodetic data together with the use of a catalog of 3‐D relocated aftershocks allows us to constrain the rupture geometries and the coseismic and postseismic slip distributions for the two main events (Mw 6.1 and 6.0) of the sequence and to explore how these thrust events have interacted with each other. Dislocation modeling reveals that the first event ruptured a slip patch located in the center of the Middle Ferrara thrust with up to 1 m of reverse slip. The modeling of the second event, located about 15 km to the southwest, indicates a main patch with up to 60 cm of slip initiated in the deeper and flatter portion of the Mirandola thrust and progressively propagated postseismically toward the top section of the rupture plane, where most of the aftershocks and afterslip occurred. Our results also indicate that between the two main events, a third thrust segment was activated releasing a pulse of aseismic slip equivalent to a Mw 5.8 event. Coulomb stress changes suggest that the aseismic event was likely triggered by the preceding main shock and that the aseismic slip event probably brought the second fault closer to failure. Our findings show significant correlations between static stress changes and seismicity and suggest that stress interaction between earthquakes plays a significant role among continental en echelon thrusts.

show abstract

Section: Discussionsupporting

confidence: 85%

Section: Inversion Of Geodetic Datasupporting

confidence: 91%

Section: The 2012 Emilia Earthquake Sequencementioning

confidence: 99%

See 1 more Smart Citation

New insights into fault activation and stress transfer between en echelon thrusts: The 2012 Emilia, Northern Italy, earthquake sequence

et al. 2016

View full text Add to dashboard Cite

show abstract

“…An example is the regional study of the 2002 February 14 M w 4.8 earthquake in Udine, Northern Italy, where the 1-D crustal model used in the source inversions is perturbed by up to 30 per cent and the moment tensor is still well resolved (Šílený 2004). More recently, Scognamiglio et al (2016) reported a variability of fault strike, dip, and rake of about 10 • in a study of the M w 5.9 Emilia (Po Plain, Italy) 2012 earthquake, when testing five different 1-D Earth models and one 3-D structure model. Here, changes in the 1-D and 3-D Earth models used in the source inversions led to a larger variability in the retrieved fault parameters than in these studies (15 • -30 • in fault strike, 5 • -20 • in fault dip, and 20 • -60 • in rake).…”

Section: Discussionmentioning

confidence: 99%

“…Several studies have investigated various factors contributing to moment tensor uncertainties, such as, data noise, restrictions in the forward modelling approach, and the earth model used (e.g. Ferreira & Woodhouse 2006;Hjörleifsdöttir & Ekström 2010;Ferreira et al 2011;Valentine & Trampert 2012;Duputel et al 2012a;Weston et al 2011;Scognamiglio et al 2016). In addition, probabilistic inversion approaches including error quantification are also progressing (e.g.…”

mentioning

confidence: 99%

On the robustness of seismic moment tensor inversions for mid-ocean earthquakes: the Azores archipelago

Frietsch

Ferreira

Vales

et al. 2018

Geophysical Journal International

View full text Add to dashboard Cite

S U M M A R YSource models of mid-oceanic earthquakes are often based only on far-field, teleseismic data. The uncertainties of all source parameters are rarely quantified, which restricts our understanding of how these events slip and how oceanic lithosphere is formed. Here, we perform moment tensor inversions for five M w 4.6-5.9 earthquakes that occurred in the Azores archipelago near the Mid-Atlantic Ridge in 2013-2016, taking advantage of the recently expanded seismic network in the region. We assess moment tensor uncertainties due to data and Earth model variability as well as the robustness of teleseismic versus local data inversions. We find that for the events studied: (i) existing 1-D Earth models of the region based on receiver function data lead to a slightly improved data fit of local data compared to a widely used regional model based on active seismic surveys; and (ii) using different 1-D Earth models in the local data inversions leads to a variability in the retrieved source parameters of 15 • -30 • in fault strike, 5 • -20 • in dip, and 20 • -60 • in rake, depending on the earthquake's magnitude and location. We study in detail the M w 5.9 2013 April 30 Povoação basin earthquake using 1-D and 3-D waveform modelling, for which reported values of strike, dip, and rake in earthquake catalogues differ by 60 • , 35 • , and 80 • . We find that our moment tensor solutions show a lower variability than in the catalogues and exhibit a persistent non-double-couple component of ∼40-60 per cent, which is not due to a volumetric change. We suggest that it is potentially due to geometrically complex faulting in the Povoação basin, notably curved faults. We find that the retrieved moment tensor solutions depend strongly on the earthquake's location. If an accurate location is used, joint inversions of local and teleseismic data can help to stabilize moment tensor solutions of oceanic earthquakes and reduce parameter trade-offs, compared to inversions of local data alone.

show abstract

Bayesian seismic source inversion with a 3-D Earth model of the Japanese Islands

Simutė

Boehm

Krischer³

et al. 2022

Preprint

View full text Add to dashboard Cite

We present probabilistic centroid-moment tensor solutions inferred from the combination of Hamiltonian Monte Carlo sampling and a 3-D full-waveform inversion Earth model of the Japanese islands. While the former provides complete posterior probability densities, the latter allows us to exploit waveform data with periods as low as 15 s. For the computation of Green's functions, we employ spectral-element simulations through the radially anisotropic and visco-elastic model, leading to substantial improvements of data fit compared to layered models. Focusing on 13 M w 4.8-M w 5.3 offshore earthquakes with a significant non-double-couple (non-DC) component, we simultaneously infer the centroid location, time and moment tensor without any a priori constraints on the faulting mechanism. Furthermore, we perform the inversions across several period bands, varying the minimum period between 15 and 50 s. Accounting for 3-D Earth structure at shorter periods can increase the double-couple (DC) component of an event, compared to the GCMT solution, by tens of percent. This suggests that non-DC events in the GCMT catalog may result from unmodeled Earth structure and the related limitation to longer-period data. We also observe that significant changes in source parameters, and the DC component in particular, may be related to only small waveform changes, thereby accentuating the importance of a reliable Earth model. Posterior probability density distributions become increasingly multimodal for shorter-period data that provide tighter constraints on source parameters. This implies, in our specific case, that stochastic approaches to the source inversion problem are required for periods below ∼20 s to avoid trapping in local minima. Plain Language SummaryIn the majority of global earthquake catalogs, the earthquake solution, that is, centroid location, time and a rupture mechanism, is typically inferred assuming a 1-D Earth model. However, both earthquake source and Earth structure contribute to seismic recordings, meaning that unaccounted structure might map into and pollute the source solution. In this study we use a 3-D Earth structure of the Japanese islands to model the waveforms and infer earthquake parameters of 13 small-to-moderate magnitude offshore events. We do not put any a priori constraints on the faulting mechanism and let it be determined by the data. We perform stochastic inversions, which provide us with a collection of all plausible models ranked by their respective probability. When a 3-D Earth structure at shorter periods is taken into account, the earthquake mechanisms, investigated in this study, can be largely explained by a slip on the fault. We also observe that significant changes in source parameters may be related to tiny waveform changes, thereby accentuating the importance of a reliable Earth model.

show abstract

Uncertainty estimations for moment tensor inversions: the issue of the 2012 May 20 Emilia earthquake

Cited by 22 publications

References 32 publications

New insights into fault activation and stress transfer between en echelon thrusts: The 2012 Emilia, Northern Italy, earthquake sequence

New insights into fault activation and stress transfer between en echelon thrusts: The 2012 Emilia, Northern Italy, earthquake sequence

On the robustness of seismic moment tensor inversions for mid-ocean earthquakes: the Azores archipelago

Bayesian seismic source inversion with a 3-D Earth model of the Japanese Islands

Contact Info

Product

Resources

About