TY - JOUR A1 - Bindi, Dino A1 - Cotton, Fabrice A1 - Spallarossa, Daniele A1 - Picozzi, Matteo A1 - Rivalta, Eleonora T1 - Temporal variability of ground shaking and stress drop in Central Italy BT - A Hint for Fault Healing? JF - Bulletin of the Seismological Society of America N2 - Ground‐motion prediction equations (GMPEs) are calibrated to predict the intensity of ground shaking at any given location, based on earthquake magnitude, source‐to‐site distance, local soil amplifications, and other parameters. GMPEs are generally assumed to be independent of time; however, evidence is increasing that large earthquakes modify the shallow soil conditions and those of the fault zone for months or years. These changes may affect the intensity of shaking and result in time‐dependent effects that can potentially be resolved by analyzing between‐event residuals (residuals between observed and predicted ground motion for individual earthquakes averaged over all stations). Here, we analyze a data set of about 65,000 recordings for about 1400 earthquakes in the moment magnitude range 2.5–6.5 that occurred in central Italy from 2008 to 2017 to capture the temporal variability of the ground shaking at high frequency. We first compute between‐event residuals for each earthquake in the Fourier domain with respect to a GMPE developed ad hoc for the analyzed data set. The between‐events show large changes after the occurrence of mainshocks such as the 2009 Mw 6.3 L'Aquila, the 2016 Mw 6.2 Amatrice, and Mw 6.5 Norcia earthquakes. Within the time span of a few months after the mainshocks, the between‐event contribution to the ground shaking varies by a factor 7. In particular, we find a large drop in the between‐events in the aftermath of the L'Aquila earthquake, followed by a slow positive trend that leads to a recovery interrupted by a new drop at the beginning of 2014. We also quantify the frequency‐dependent correlation between the Brune stress drop Δσ and the between‐events. We find that the temporal changes of Δσ resemble those of the between‐event residuals; in particular, during the period when the between‐events show the positive trend, the average logarithm of Δσ increases with an annual rate of 0.19 (i.e., the amplification factor for Δσ is 1.56 per year). Breakpoint analysis located a change in the linear trend coefficients of Δσ versus time in February 2014, although no large earthquakes occurred at that time. Finally, the temporal variability of Δσ mirrors the relative seismic‐velocity variations observed in previous studies for the same area and period, suggesting that both crack healing along the main fault system and healing of microcracks distributed at shallow depths throughout the surrounding region might be necessary to explain the wider observations of postearthquake recovery. Y1 - 2018 U6 - https://doi.org/10.1785/0120180078 SN - 0037-1106 SN - 1943-3573 VL - 108 IS - 4 SP - 1853 EP - 1863 PB - Seismological Society of America CY - Albany ER - TY - JOUR A1 - Bindi, Dino A1 - Kotha, Sreeram Reddy A1 - Weatherill, Graeme A1 - Lanzano, Giovanni A1 - Luzi, Lucia A1 - Cotton, Fabrice T1 - The pan-European engineering strong motion (ESM) flatfile BT - consistency check via residual analysis JF - Bulletin of earthquake engineering : official publication of the European Association for Earthquake Engineering N2 - We present the results of a consistency check performed over the flatfile extracted from the engineering strong motion (ESM) database. The flatfile includes 23,014 recordings from 2179 earthquakes in the magnitude range from 3.5 to 7.8 that occurred since the 1970s in Europe and Middle East, as presented in the companion article by Lanzano et al. (Bull Earthq Eng, 2018a). The consistency check is developed by analyzing different residual distributions obtained from ad-hoc ground motion prediction equations for the absolute spectral acceleration (SA), displacement and Fourier amplitude spectra (FAS). Only recordings from earthquakes shallower than 40 km are considered in the analysis. The between-event, between-station and event-and-station corrected residuals are computed by applying a mixed-effect regression. We identified those earthquakes, stations, and recordings showing the largest deviations from the GMPE median predictions, and also evaluated the statistical uncertainty on the median model to get insights on the applicable magnitude–distance ranges and the usable period (or frequency) range. We observed that robust median predictions are obtained up to 8 s for SA and up to 20 Hz for FAS, although median predictions for Mw ≥ 7 show significantly larger uncertainties with ‘bumps’ starting above 5 s for SA and below 0.3 Hz for FAS. The between-station variance dominates over the other residual variances, and the dependence of the between-station residuals on logarithm of Vs30 is well-described by a piece-wise linear function with period-dependent slopes and hinge velocity around 580 m/s. Finally, we compared the between-event residuals obtained by considering two different sources of moment magnitude. The results show that, at long periods, the between-event terms from the two regressions have a weak correlation and the overall between-event variability is dissimilar, highlighting the importance of magnitude source in the regression results. KW - Ground motion prediction equation KW - Residual analysis KW - European strong motion data Y1 - 2018 U6 - https://doi.org/10.1007/s10518-018-0466-x SN - 1570-761X SN - 1573-1456 VL - 17 IS - 2 SP - 583 EP - 602 PB - Springer CY - Dordrecht ER - TY - JOUR A1 - Bindi, Dino A1 - Marzorati, Simone A1 - Parolai, Stefano A1 - Strollo, Angelo A1 - Jaeckel, Karl-Heinz T1 - Empirical spectral ratios estimated in two deep sedimentary basins using microseisms recorded by short-period seismometers N2 - In this work, we analyse continuous measurements of microseisms to assess the reliability of the fundamental resonance frequency estimated by means of the horizontal-to-vertical (H/V) spectral ratio within the 0.1-1 Hz frequency range, using short-period sensors (natural period of 1 s). We apply the H/V technique to recordings of stations installed in two alluvial basins with different sedimentary cover thicknesses-the Lower Rhine Embayment (Germany) and the Gubbio Plain (Central Italy). The spectral ratios are estimated over the time-frequency domain, and we discuss the reliability of the results considering both the variability of the microseism activity and the amplitude of the instrumental noise. We show that microseisms measured by short period sensors allow the retrieval of fundamental resonance frequencies greater than about 0.1-0.2 Hz, with this lower frequency bound depending on the relative amplitude of the microseism signal and the self-noise of the instruments. In particular, we show an example where the considered short-period sensor is connected to instruments characterized by an instrumental noise level which allows detecting only fundamental frequencies greater than about 0.4 Hz. Since the frequency at which the peak of the H/V spectral ratio is biased depends upon the seismic signal-to-instrument noise ratio, the power spectral amplitude of instrumental self- noise should be always considered when interpreting the frequency of the peak as the fundamental resonance frequency of the investigated site. Y1 - 2009 UR - http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1365-246X U6 - https://doi.org/10.1111/j.1365-246X.2008.03958.x SN - 0956-540X ER - TY - JOUR A1 - Bindi, Dino A1 - Picozzi, Matteo A1 - Spallarossa, Daniele A1 - Cotton, Fabrice A1 - Kotha, Sreeram Reddy T1 - Impact of Magnitude Selection on Aleatory Variability Associated with Ground-Motion Prediction Equations BT - Part II-Analysis of the Between-Event Distribution in Central Italy JF - Bulletin of the Seismological Society of America N2 - We derive a set of regional ground-motion prediction equations (GMPEs) in the Fourier amplitude spectra (FAS-GMPE) and in the spectral acceleration (SA-GMPE) domains for the purpose of interpreting the between-event residuals in terms of source parameter variability. We analyze a dataset of about 65,000 recordings generated by 1400 earthquakes (moment magnitude 2: 5 <= M-w <= 6: 5, hypocentral distance R-hypo <= 150 km) that occurred in central Italy between January 2008 and October 2017. In a companion article (Bindi, Spallarossa, et al., 2018), the nonparametric acceleration source spectra were interpreted in terms of omega-square models modified to account for deviations from a high-frequency flat plateau through a parameter named k(source). Here, the GMPEs are derived considering the moment (M-w), the local (M-L), and the energy (M-e) magnitude scales, and the between-event residuals are computed as random effects. We show that the between-event residuals for the FAS-GMPE implementing M-w are correlated with stress drop, with correlation coefficients increasing with increasing frequency up to about 10 Hz. Contrariwise, the correlation is weak for the FAS-GMPEs implementing M-L and M-e, in particular between 2 and 5 Hz, where most of the corner frequencies lie. At higher frequencies, all models show a strong correlation with k(source). The correlation with the source parameters reflects in a different behavior of the standard deviation tau of the between-event residuals with frequency. Although tau is smaller for the FAS-GMPE using M-w below 1.5 Hz, at higher frequencies, the model implementing either M-L or M-e shows smaller values, with a reduction of about 30% at 3 Hz (i.e., from 0.3 for M-w to 0.1 for M-L). We conclude that considering magnitude scales informative for the stress-drop variability allows to reduce the between-event variability with a significant impact on the hazard assessment, in particular for studies in which the ergodic assumption on site is removed. Y1 - 2019 U6 - https://doi.org/10.1785/0120180239 SN - 0037-1106 SN - 1943-3573 VL - 109 IS - 1 SP - 251 EP - 262 PB - Seismological Society of America CY - Albany ER - TY - JOUR A1 - Bindi, Dino A1 - Spallarossa, D. A1 - Picozzi, M. A1 - Scafidi, D. A1 - Cotton, Fabrice T1 - Impact of magnitude selection on aleatory variability associated with ground-motion prediction equations BT - Part I-Local, Energy, and Moment Magnitude Calibration and Stress-Drop Variability in Central Italy JF - Bulletin of the Seismological Society of America N2 - In this study, we analyzed 10 yrs of seismicity in central Italy from 2008 to 2017, a period witnessing more than 1400 earthquakes in the magnitude range 2.5≤Mw≤6.5⁠. The data set includes the main sequences that have occurred in the area, including those associated with the 2009 Mw 6.3 L'Aquila earthquake and the 2016–2017 sequence (⁠Mw 6.2 Amatrice, Mw 6.1 Visso, and Mw 6.5 Norcia earthquakes). We calibrated a local magnitude scale, investigating the impact of changing the reference distance at which the nonparametric attenuation is tied to the zero‐magnitude attenuation function for southern California. We also developed an attenuation model to compute the radiated seismic energy (⁠Es⁠) from the time integral of the squared ground‐motion velocity. Seismic moment (⁠M0⁠) and stress drop (⁠Δσ⁠) were estimated for each earthquake by fitting a ω‐square model to the source spectra obtained by applying a nonparametric spectral inversion. The Δσ‐values vary over three orders of magnitude from about 0.1 to 10 MPa, the larger values associated with the mainshocks. The Δσ‐values describe a lognormal distribution with mean and standard deviation equal to log(Δσ)=(−0.25±0.45) (i.e., the mean Δσ is 0.57 MPa, with a 95% confidence interval from 0.08 to 4.79 MPa). The Δσ variability introduces a spread in the distribution of seismic energy versus moment, with differences in energy up two orders of magnitudes for earthquakes with the same moment. The variability in the high‐frequency spectral levels is captured by the local magnitude (⁠ML⁠), which scales with radiated energy as ML=(−1.59+0.52logEs) for logEs≤10.26 and ML=(−1.38+0.50logEs) otherwise. As the peak ground velocity increases with increasing Δσ⁠, local and energy magnitudes perform better than moment magnitude as predictors for the shaking potential. The availability of different magnitude scales and source parameters for a large earthquake population will help characterize the between‐event ground‐motion variability in central Italy. Y1 - 2018 U6 - https://doi.org/10.1785/0120170356 SN - 0037-1106 SN - 1943-3573 VL - 108 IS - 3A SP - 1427 EP - 1442 PB - Seismological Society of America CY - Albany ER - TY - JOUR A1 - Dahm, Torsten A1 - Heimann, Sebastian A1 - Funke, Sigward A1 - Wendt, Siegfried A1 - Rappsilber, Ivo A1 - Bindi, Dino A1 - Plenefisch, Thomas A1 - Cotton, Fabrice T1 - Seismicity in the block mountains between Halle and Leipzig, Central Germany BT - centroid moment tensors, ground motion simulation, and felt intensities of two M approximate to 3 earthquakes in 2015 and 2017 JF - Journal of seismology N2 - On April 29, 2017 at 0:56 UTC (2:56 local time), an M (W) = 2.8 earthquake struck the metropolitan area between Leipzig and Halle, Germany, near the small town of Markranstadt. The earthquake was felt within 50 km from the epicenter and reached a local intensity of I (0) = IV. Already in 2015 and only 15 km northwest of the epicenter, a M (W) = 3.2 earthquake struck the area with a similar large felt radius and I (0) = IV. More than 1.1 million people live in the region, and the unusual occurrence of the two earthquakes led to public attention, because the tectonic activity is unclear and induced earthquakes have occurred in neighboring regions. Historical earthquakes south of Leipzig had estimated magnitudes up to M (W) ae 5 and coincide with NW-SE striking crustal basement faults. We use different seismological methods to analyze the two recent earthquakes and discuss them in the context of the known tectonic structures and historical seismicity. Novel stochastic full waveform simulation and inversion approaches are adapted for the application to weak, local earthquakes, to analyze mechanisms and ground motions and their relation to observed intensities. We find NW-SE striking normal faulting mechanisms for both earthquakes and centroid depths of 26 and 29 km. The earthquakes are located where faults with large vertical offsets of several hundred meters and Hercynian strike have developed since the Mesozoic. We use a stochastic full waveform simulation to explain the local peak ground velocities and calibrate the method to simulate intensities. Since the area is densely populated and has sensitive infrastructure, we simulate scenarios assuming that a 12-km long fault segment between the two recent earthquakes is ruptured and study the impact of rupture parameters on ground motions and expected damage. KW - Deep crustal intraplate seismicity KW - Centroid moment tensor of M approximate to 3 earthquakes KW - Observed and simulated ground motions Y1 - 2018 U6 - https://doi.org/10.1007/s10950-018-9746-9 SN - 1383-4649 SN - 1573-157X VL - 22 IS - 4 SP - 985 EP - 1003 PB - Springer CY - Dordrecht ER - TY - GEN A1 - Dahm, Torsten A1 - Heimann, Sebastian A1 - Funke, Sigward A1 - Wendt, Siegfried A1 - Rappsilber, Ivo A1 - Bindi, Dino A1 - Plenefisch, Thomas A1 - Cotton, Fabrice T1 - Correction to: Seismicity in the block mountains between Halle and Leipzig, Central Germany: centroid moment tensors, ground motion simulation, and felt intensities of two M approximate to 3 earthquakes in 2015 and 2017 (vol 22, pg 985, 2018) T2 - Journal of seismology Y1 - 2018 U6 - https://doi.org/10.1007/s10950-018-9773-6 SN - 1383-4649 SN - 1573-157X VL - 22 IS - 6 SP - 1669 EP - 1671 PB - Springer CY - Dordrecht ER - TY - JOUR A1 - Di Giacomo, Domenico A1 - Bindi, Dino A1 - Parolai, Stefano A1 - Oth, Adrien T1 - Residual analysis of teleseismic P-wave energy magnitude estimates: inter- and intrastation variability JF - Geophysical journal international N2 - P>Computing the magnitude of an earthquake requires correcting for the propagation effects from the source to the receivers. This is often accomplished by performing numerical simulations using a suitable Earth model. In this work, the energy magnitude M(e) is considered and its determination is performed using theoretical spectral amplitude decay functions over teleseismic distances based on the global Earth model AK135Q. Since the high frequency part (above the corner frequency) of the source spectrum has to be considered in computing M(e), the influence of propagation and site effects may not be negligible and they could bias the single station M(e) estimations. Therefore, in this study we assess the inter- and intrastation distributions of errors by considering the M(e) residuals computed for a large data set of earthquakes recorded at teleseismic distances by seismic stations deployed worldwide. To separate the inter- and intrastation contribution of errors, we apply a maximum likelihood approach to the M(e) residuals. We show that the interstation errors (describing a sort of site effect for a station) are within +/- 0.2 magnitude units for most stations and their spatial distribution reflects the expected lateral variation affecting the velocity and attenuation of the Earth's structure in the uppermost layers, not accounted for by the 1-D AK135Q model. The variance of the intrastation error distribution (describing the record-to-record component of variability) is larger than the interstation one (0.240 against 0.159), and the spatial distribution of the errors is not random but shows specific patterns depending on the source-to-station paths. The set of coefficients empirically determined may be used in the future to account for the heterogeneities of the real Earth not considered in the theoretical calculations of the spectral amplitude decay functions used to correct the recorded data for propagation effects. KW - Time series analysis KW - Earthquake source observations KW - Body waves KW - Site effects KW - Wave propagation Y1 - 2011 U6 - https://doi.org/10.1111/j.1365-246X.2011.05019.x SN - 0956-540X VL - 185 IS - 3 SP - 1444 EP - 1454 PB - Wiley-Blackwell CY - Malden ER - TY - JOUR A1 - Douglas, John A1 - Akkar, Sinan A1 - Ameri, Gabriele A1 - Bard, Pierre-Yves A1 - Bindi, Dino A1 - Bommer, Julian J. A1 - Bora, Sanjay Singh A1 - Cotton, Fabrice A1 - Derras, Boumediene A1 - Hermkes, Marcel A1 - Kuehn, Nicolas Martin A1 - Luzi, Lucia A1 - Massa, Marco A1 - Pacor, Francesca A1 - Riggelsen, Carsten A1 - Sandikkaya, M. Abdullah A1 - Scherbaum, Frank A1 - Stafford, Peter J. A1 - Traversa, Paola T1 - Comparisons among the five ground-motion models developed using RESORCE for the prediction of response spectral accelerations due to earthquakes in Europe and the Middle East JF - Bulletin of earthquake engineering : official publication of the European Association for Earthquake Engineering N2 - This article presents comparisons among the five ground-motion models described in other articles within this special issue, in terms of data selection criteria, characteristics of the models and predicted peak ground and response spectral accelerations. Comparisons are also made with predictions from the Next Generation Attenuation (NGA) models to which the models presented here have similarities (e.g. a common master database has been used) but also differences (e.g. some models in this issue are nonparametric). As a result of the differing data selection criteria and derivation techniques the predicted median ground motions show considerable differences (up to a factor of two for certain scenarios), particularly for magnitudes and distances close to or beyond the range of the available observations. The predicted influence of style-of-faulting shows much variation among models whereas site amplification factors are more similar, with peak amplification at around 1s. These differences are greater than those among predictions from the NGA models. The models for aleatory variability (sigma), however, are similar and suggest that ground-motion variability from this region is slightly higher than that predicted by the NGA models, based primarily on data from California and Taiwan. KW - Strong-motion data KW - Ground-motion models KW - Ground-motion prediction equations KW - Style of faulting KW - Site amplification KW - Aleatory variability KW - Epistemic uncertainty KW - Europe KW - Middle East Y1 - 2014 U6 - https://doi.org/10.1007/s10518-013-9522-8 SN - 1570-761X SN - 1573-1456 VL - 12 IS - 1 SP - 341 EP - 358 PB - Springer CY - Dordrecht ER - TY - JOUR A1 - Grünthal, Gottfried A1 - Stromeyer, Dietrich A1 - Bosse, Christian A1 - Cotton, Fabrice A1 - Bindi, Dino T1 - The probabilistic seismic hazard assessment of Germany-version 2016, considering the range of epistemic uncertainties and aleatory variability JF - Bulletin of earthquake engineering : official publication of the European Association for Earthquake Engineering N2 - The basic seismic load parameters for the upcoming national design regulation for DIN EN 1998-1/NA result from the reassessment of the seismic hazard supported by the German Institution for Civil Engineering (DIBt). This 2016 version of the national seismic hazard assessment for Germany is based on a comprehensive involvement of all accessible uncertainties in models and parameters and includes the provision of a rational framework for integrating ranges of epistemic uncertainties and aleatory variabilities in a comprehensive and transparent way. The developed seismic hazard model incorporates significant improvements over previous versions. It is based on updated and extended databases, it includes robust methods to evolve sets of models representing epistemic uncertainties, and a selection of the latest generation of ground motion prediction equations. The new earthquake model is presented here, which consists of a logic tree with 4040 end branches and essential innovations employed for a realistic approach. The output specifications were designed according to the user oriented needs as suggested by two review teams supervising the entire project. Seismic load parameters, for rock conditions of nu(S30) = 800 m/s, are calculated for three hazard levels (10, 5 and 2% probability of occurrence or exceedance within 50 years) and delivered in the form of uniform hazard spectra, within the spectral period range 0.02-3 s, and seismic hazard maps for peak ground acceleration, spectral response accelerations and for macroseismic intensities. Results are supplied as the mean, the median and the 84th percentile. A broad analysis of resulting uncertainties of calculated seismic load parameters is included. The stability of the hazard maps with respect to previous versions and the cross-border comparison is emphasized. KW - Seismic hazard KW - Germany KW - DIN EN 1998-1/NA KW - Seismic load parameters Y1 - 2018 U6 - https://doi.org/10.1007/s10518-018-0315-y SN - 1570-761X SN - 1573-1456 VL - 16 IS - 10 SP - 4339 EP - 4395 PB - Springer CY - Dordrecht ER -