Analysis of strong-motion data of the 1990 Eastern Sicily earthquake
The strong motion accelerograms recorded during the 1990 Eastern Sicily earthquake have been analyzed to investigate source and attenuation parameters. Peak ground motions (peak acceleration, velocity and displacement) overestimate the values predicted by the empirical scaling law proposed for other...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
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Istituto Nazionale di Geofisica e Vulcanologia (INGV)
1995-06-01
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| Series: | Annals of Geophysics |
| Subjects: | |
| Online Access: | http://www.annalsofgeophysics.eu/index.php/annals/article/view/4124 |
| _version_ | 1818426162441879552 |
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| author | E. Boschi R. Berardi A. Rovelli M. Cocco M. Di Bona |
| author_facet | E. Boschi R. Berardi A. Rovelli M. Cocco M. Di Bona |
| author_sort | E. Boschi |
| collection | DOAJ |
| description | The strong motion accelerograms recorded during the 1990 Eastern Sicily earthquake have been analyzed to investigate source and attenuation parameters. Peak ground motions (peak acceleration, velocity and displacement) overestimate the values predicted by the empirical scaling law proposed for other Italian earthquakes, suggesting that local site response and propagation path effects play an important role in interpreting the observed time histories. The local magnitude, computed from the strong motion accelerograms by synthesizing the Wood-Anderson response, is ML = 5.9, that is sensibly larger than the local magnitude estimated at regional distances from broad-band seismograms (ML = 5.4). The standard omega-square source spectral model seems to be inadequate to describe the observed spectra over the entire frequency band from 0.2 to 20 Hz. The seismic moment estimated from the strong motion accelerogram recorded at the closest rock site (Sortino) is Mo = 0.8 x 1024 dyne.cm, that is roughly 4.5 times lower than the value estimated at regional distances (Mo = 3.7 x 1024 dyne.cm) from broad-band seismograms. The corner frequency estimated from the accelera- tion spectra i.5 J; = 1.3 Hz, that is close to the inverse of the dUl.ation of displacement pulses at the two closest recording sites. This value of corner tì.equency and the two values of seismic moment yield a Brune stress drop larger than 500 bars. However, a corner frequency value off; = 0.6 Hz and the seismic moment resulting from regional data allows the acceleration spectra to be reproduced on the entire available frequency band yielding to a Brune stress drop of 210 bars. The ambiguity on the corner frequency value associated to this earthquake is due to the limited frequency bandwidth available on the strong motion recordil1gs. Assuming the seismic moment estimated at regional distances from broad-band data, the moment magnitude for this earthquake is 5.7. The higher local magnitude (5.9) compared with the moment magnitude (5.7) is due to the weak regional attenuation. Beside this, site amplifications due to surface geology have produced the highest peak ground motions among those observed at the strong motion sites. |
| first_indexed | 2024-12-14T14:25:27Z |
| format | Article |
| id | doaj.art-29cbe62272514fb79d31ae61e21ddd87 |
| institution | Directory Open Access Journal |
| issn | 1593-5213 2037-416X |
| language | English |
| last_indexed | 2024-12-14T14:25:27Z |
| publishDate | 1995-06-01 |
| publisher | Istituto Nazionale di Geofisica e Vulcanologia (INGV) |
| record_format | Article |
| series | Annals of Geophysics |
| spelling | doaj.art-29cbe62272514fb79d31ae61e21ddd872022-12-21T22:57:59ZengIstituto Nazionale di Geofisica e Vulcanologia (INGV)Annals of Geophysics1593-52132037-416X1995-06-0138210.4401/ag-4124Analysis of strong-motion data of the 1990 Eastern Sicily earthquakeE. BoschiR. BerardiA. RovelliM. CoccoM. Di BonaThe strong motion accelerograms recorded during the 1990 Eastern Sicily earthquake have been analyzed to investigate source and attenuation parameters. Peak ground motions (peak acceleration, velocity and displacement) overestimate the values predicted by the empirical scaling law proposed for other Italian earthquakes, suggesting that local site response and propagation path effects play an important role in interpreting the observed time histories. The local magnitude, computed from the strong motion accelerograms by synthesizing the Wood-Anderson response, is ML = 5.9, that is sensibly larger than the local magnitude estimated at regional distances from broad-band seismograms (ML = 5.4). The standard omega-square source spectral model seems to be inadequate to describe the observed spectra over the entire frequency band from 0.2 to 20 Hz. The seismic moment estimated from the strong motion accelerogram recorded at the closest rock site (Sortino) is Mo = 0.8 x 1024 dyne.cm, that is roughly 4.5 times lower than the value estimated at regional distances (Mo = 3.7 x 1024 dyne.cm) from broad-band seismograms. The corner frequency estimated from the accelera- tion spectra i.5 J; = 1.3 Hz, that is close to the inverse of the dUl.ation of displacement pulses at the two closest recording sites. This value of corner tì.equency and the two values of seismic moment yield a Brune stress drop larger than 500 bars. However, a corner frequency value off; = 0.6 Hz and the seismic moment resulting from regional data allows the acceleration spectra to be reproduced on the entire available frequency band yielding to a Brune stress drop of 210 bars. The ambiguity on the corner frequency value associated to this earthquake is due to the limited frequency bandwidth available on the strong motion recordil1gs. Assuming the seismic moment estimated at regional distances from broad-band data, the moment magnitude for this earthquake is 5.7. The higher local magnitude (5.9) compared with the moment magnitude (5.7) is due to the weak regional attenuation. Beside this, site amplifications due to surface geology have produced the highest peak ground motions among those observed at the strong motion sites.http://www.annalsofgeophysics.eu/index.php/annals/article/view/4124strong motionsite amplificationstress dropspectral analysisanelastic attenuation |
| spellingShingle | E. Boschi R. Berardi A. Rovelli M. Cocco M. Di Bona Analysis of strong-motion data of the 1990 Eastern Sicily earthquake Annals of Geophysics strong motion site amplification stress drop spectral analysis anelastic attenuation |
| title | Analysis of strong-motion data of the 1990 Eastern Sicily earthquake |
| title_full | Analysis of strong-motion data of the 1990 Eastern Sicily earthquake |
| title_fullStr | Analysis of strong-motion data of the 1990 Eastern Sicily earthquake |
| title_full_unstemmed | Analysis of strong-motion data of the 1990 Eastern Sicily earthquake |
| title_short | Analysis of strong-motion data of the 1990 Eastern Sicily earthquake |
| title_sort | analysis of strong motion data of the 1990 eastern sicily earthquake |
| topic | strong motion site amplification stress drop spectral analysis anelastic attenuation |
| url | http://www.annalsofgeophysics.eu/index.php/annals/article/view/4124 |
| work_keys_str_mv | AT eboschi analysisofstrongmotiondataofthe1990easternsicilyearthquake AT rberardi analysisofstrongmotiondataofthe1990easternsicilyearthquake AT arovelli analysisofstrongmotiondataofthe1990easternsicilyearthquake AT mcocco analysisofstrongmotiondataofthe1990easternsicilyearthquake AT mdibona analysisofstrongmotiondataofthe1990easternsicilyearthquake |