1,721,050 research outputs found
A test of a physically-based strong ground motion prediction methodology with the 26 September 1997, Mw = 6.0 Colfiorito (Umbria-Marche sequence), Italy earthquake.
No full textWe test the physically-based ground motion hazard prediction methodology of Hutchings et al. [Hutchings, L., Ioannidou, E., Kalogeras, I., Voulgaris, N., Savy, J., Foxall, W., Scognamiglio, L., and Stavrakakis, G., (2007). A physically-based strong ground motion prediction methodology; Application to PSHA and the 1999 M = 6.0 Athens Earthquake. Geophys. J. Int. 168, 569–680.] through an a posteriori prediction of the 26 September 1997, Mw 6.0 Colfiorito (Umbria–Marche, Italy) earthquake at four stations. By “physically-based” we refer to ground motion synthesized with quasi-dynamic rupture models derived from physics and an understanding of the earthquake process. We test five hypotheses proposed by Hutchings et al. [Hutchings, L., Ioannidou, E., Kalogeras, I., Voulgaris, N., Savy, J., Foxall, W., Scognamiglio, L., and Stavrakakis, G., (2007). A physically-based strong ground motion prediction methodology; Application to PSHA and the 1999 M = 6.0 Athens Earthquake. Geophys. J. Int. 168, 569–680.] that support application of the methodology to physically-based probabilistic seismic hazard or risk analysis.
We use two methods to test the hypotheses. First, we test whether observed records fall within the 68% log-normal confidence interval for the distribution of absolute acceleration response (AAR), pseudo velocity response (PSV), and Fourier amplitude spectra (FFT) created by a suite of source models. We also used the godness of fit between synthesized seismograms to verify whether at least one of the source models in the suite generates seismograms that match the observed waveforms, and if good fits to seismograms are due to source models that are close to what is actually known about the Colfiorito earthquake.
We tested the hypotheses with a range of source parameters proposed by Hutchings et al. [Hutchings, L., Ioannidou, E., Kalogeras, I., Voulgaris, N., Savy, J., Foxall, W., Scognamiglio, L., and Stavrakakis, G., (2007). A physically-based strong ground motion prediction methodology; Application to PSHA and the 1999 M = 6.0 Athens Earthquake. Geophys. J. Int. 168, 569–680.]. We synthesized records from 100 rupture scenarios that were generated by a Monte Carlo selection of parameters within the range. This range was based upon having some prior knowledge of where the earthquake would occur. Observed values of AAR, PSV and FFT fit within the 68% confidence interval for all four stations, and one of the models generated seismograms that had a good fit compared to the observations.
Moreover, a strict test for validating a physically-based ground motion hazard prediction methodology is that as more information is known about the source, the uncertainty of the prediction should narrow, but still include the actual ground motion. Then, we tightened the source parameters to be centered about the known parameters for the Colfiorito earthquake, and allowed for less uncertainty in their values. We found this to be true for this test. While the 68% confidence interval narrowed from a factor of ± about 4 to ± about 2 for the distributions, observed values of AAR, PSV and FFT still fit within the distributions for all four stations. Ultimately, we have calculated peak ground velocity (PGV) and peak ground acceleration (PGA) for all the synthetic seismograms obtained from the computed scenarios, and we have found that they are comparable with the actual and with those from the attenuation relation.
We conclude that the methodology of Hutchings et al. [Hutchings, L., Ioannidou, E., Kalogeras, I., Voulgaris, N., Savy, J., Foxall, W., Scognamiglio, L., and Stavrakakis, G., (2007). A physically-based strong ground motion prediction methodology; Application to PSHA and the 1999 M = 6.0 Athens Earthquake. Geophys. J. Int. 168, 569–680.] is promising in giving ground motion hazard prediction estimates.Published145-1583.1. Fisica dei terremotiJCR Journalreserve
Rassegna di studi sulla gestualità delle mani: Sviluppo, categorie, funzioni e basi dei gesti
No full textStrategie interattive in situazioni di accordo e disaccordo: Uno studio sulla convergenza e divergenza
No full text
Real-Time Determination of Seismic Moment Tensor for the Italian Region
No full textWe describe the automatic (AUTO) and the reviewed (REV) seismic time-domain moment tensor (TDMT) procedures implemented recently at the Istituto Nazionale di Geofisica e Vulcanologia (INGV), Italy. The solutions are obtained from the high-quality data of the recently installed Italian broadband network and of the Mediterranean seismographic network (MedNet). AUTO- and REV-TDMT adopt the long-period full waveform inversion code developed by Dreger and Helmberger (1993). AUTO-TDMT is triggered by local and regional events with magnitude ML ≥ 3.5 detected by the INGV seismic center.Moment tensor solutions are available within about 10 min after earthquake location, and they are automatically published on the World Wide Web for solution qualities exceeding a predefined threshold. REV-TDMT solutions are posted on the World Wide Web and included in the INGV-TDMT catalog after manual revision. The catalog we describe has great potential to improve our understanding of the regional seismicity and of the ongoing tectonics because the TDMT solutions are the only moment tensors and moment magnitudes released for Italy for many of the events with ML ≤4.2
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
- …
