What can we learn from the January 2012 northern Italy earthquakes?

This note focuses on the ground motion recorded during the recent moderate earthquakes that occurred in the central part of northern Italy (Panel 1), a region that is characterized by low seismicity. For this area, the Italian seismic hazard map [Stucchi et al. 2011] assigns a maximum horizontal acceleration (rock site) of up to 0.2 g (10% probability of being exceeded in 50 yr). In the last 4 yr, this region has been struck by 9 earthquakes in the magnitude range 4 ≤Mw ≤ 5.0, with the three largest located in the Northern Apennines (the Mw 4.9 and 5.0 Parma events, in December 2008 and January 2012) and on the Po Plain (the Mw 4.9 Reggio Emila event, in January 2012). We have analyzed the strong-motion data (distance <300 km) from these events as recorded by stations belonging to the Istituto Nazionale di Geofisica e Vulcanologia (RAIS, http://rais.mi.ingv.it; RSNC, http://iside.rm.ingv.it) and the Department of Civil Protection (RAN, www.protezionecivile.it; http://itaca.mi.ingv.it). […]

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Peak horizontal acceleration and velocity from strong-motion records including records from the 1979 imperial valley, California, earthquake

Bulletin of the Seismological Society of America ◽

10.1785/bssa0710062011 ◽

1981 ◽

Vol 71 (6) ◽

pp. 2011-2038 ◽

Cited By ~ 1

Author(s):

William B. Joyner ◽

David M. Boore

Keyword(s):

Strong Motion ◽

Fault Rupture ◽

Imperial Valley ◽

Attenuation Relations ◽

Motion Data ◽

Horizontal Acceleration ◽

Anelastic Attenuation ◽

Distance Dependence ◽

Peak Horizontal Acceleration

Abstract We have taken advantage of the recent increase in strong-motion data at close distances to derive new attenuation relations for peak horizontal acceleration and velocity. This new analysis uses a magnitude-independent shape, based on geometrical spreading and anelastic attenuation, for the attenuation curve. An innovation in technique is introduced that decouples the determination of the distance dependence of the data from the magnitude dependence. The resulting equations are log A = − 1.02 + 0.249 M − log r − 0.00255 r + 0.26 P r = ( d 2 + 7.3 2 ) 1 / 2 5.0 ≦ M ≦ 7.7 log V = − 0.67 + 0.489 M − log r − 0.00256 r + 0.17 S + 0.22 P r = ( d 2 + 4.0 2 ) 1 / 2 5.3 ≦ M ≦ 7.4 where A is peak horizontal acceleration in g, V is peak horizontal velocity in cm/ sec, M is moment magnitude, d is the closest distance to the surface projection of the fault rupture in km, S takes on the value of zero at rock sites and one at soil sites, and P is zero for 50 percentile values and one for 84 percentile values. We considered a magnitude-dependent shape, but we find no basis for it in the data; we have adopted the magnitude-independent shape because it requires fewer parameters.

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Peak acceleration, velocity, and displacement from strong-motion records

Bulletin of the Seismological Society of America ◽

10.1785/bssa0700010305 ◽

1980 ◽

Vol 70 (1) ◽

pp. 305-321

Author(s):

David M. Boore ◽

William B. Joyner ◽

Adolph A. Oliver ◽

Robert A. Page

Keyword(s):

Regression Analysis ◽

Peak Velocity ◽

Strong Motion ◽

Western North America ◽

Peak Acceleration ◽

Motion Data ◽

Horizontal Acceleration ◽

Large Structures ◽

San Fernando ◽

Peak Horizontal Acceleration

abstract Strong-motion data from earthquakes of western North America are examined to provide the basis for estimating peak acceleration, velocity, and displacement as a function of distance for three magnitude classes, 5.0 to 5.7, 6.0 to 6.4, and 7.1 to 7.6. Analysis of a subset of the data from the San Fernando earthquake shows that small but statistically significant differences exist between peak values of horizontal acceleration, velocity, and displacement recorded on soil at the base of small structures and values recorded at the base of large structures. The peak acceleration tends to be less and the peak velocity and displacement to be greater at the base of large structures than at the base of small structures. In the distance range used in the regression analysis (15 to 100 km), the values of peak horizontal acceleration recorded at soil sites in the San Fernando earthquake are not significantly different from the values recorded at rock sites, but values of peak horizontal velocity and displacement are significantly greater at soil sites.

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The 2003, Mw 7.2 Fiordland earthquake, and its near-source aftershock strong motion data

Bulletin of the New Zealand Society for Earthquake Engineering ◽

10.5459/bnzsee.37.3.139-145 ◽

2004 ◽

Vol 37 (3) ◽

pp. 139-145

Author(s):

P. McGinty

Keyword(s):

New Zealand ◽

Strong Motion ◽

Data Set ◽

Strong Motion Data ◽

Preliminary Results ◽

Motion Data ◽

Magnitude Range ◽

Source Data ◽

Peak Ground Accelerations ◽

Attenuation Models

The 2003 Fiordland earthquake was not only the best ever recorded subduction interface earthquake to occur in New Zealand, it also provided the opportunity to collect near-source strong-motion data produced by its aftershocks covering a wide magnitude range. Near source strong-motion data had been lacking in the New Zealand data set, on which current attenuation models are based. Here the author presents some preliminary results relating recorded peak ground accelerations in the near-source field to current attenuation models. The near-source data from the 2003 Fiordland earthquake sequence has shown that the observed data has a greater magnitude-dependence than that predicted by the current attenuation models. This new data will help to improve current models and will lead to a better understanding of the attenuation process associated with New Zealand subduction interface earthquakes.

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The May 2012 Pianura Padana Emiliana seismic sequence: INGV strong-motion data website

Annals of Geophysics ◽

10.4401/ag-5828 ◽

2012 ◽

Vol 55 (3) ◽

Author(s):

Marco Massa ◽

Sara Lovati ◽

Rodolfo Puglia ◽

Gabriele Ameri ◽

Dario Sudati ◽

...

Keyword(s):

Focal Mechanism ◽

Web Site ◽

Strong Motion ◽

Northern Italy ◽

Seismic Network ◽

Seismic Sequence ◽

Strong Motion Data ◽

Motion Data ◽

Strong Motion Network ◽

The Web

On May 20th 2012, at 02:03:52 UTC, a ML 5.9 (Mw 6.0) earthquake struck northern Italy (http://cnt.rm.ingv.it/). The epicentre was localized at 44.89˚ N and 11.23˚ E, in an area among the cities of Ferrara, Modena and Mantova. The event occurred at a depth of about 6.3 km, and was characterized by a reverse focal mechanism (http://cnt.rm.ingv.it/tdmt.html/). From May 20th, thousand of earthquakes, the strongest of which with a ML 5.8 (May 29th, 07:00:03 UTC), occurred in the same area (http://iside.rm.ingv.it/).This note presents a new web site, www.mi.ingv.it/ISMD/ismd.html/ (Figure 1) that includes about 2000 three-component strong-motion recordings of the events with 4.0 ≤ ML ≤ 5.9 occurred in the central part of the Pianura Padana Emiliana (northern Italy) from May 20th to June 12th. The data come from all INGV strong-motion stations installed in northern Italy (i.e. strong-motion stations of the National Seismic Network, RSN [Amato and Mele 2008]; Strong-Motion Network of Northern Italy, RAIS, http://rais.mi.ingv.it/ [Augliera et al. 2011]) and selected with a minimum latitude of 43.5˚ N. The earthquake locations reported in the web site come from the National Earthquake Centre of INGV (http://cnt.rm.ingv.it/).

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The correlation of peak ground horizontal acceleration with magnitude, distance, and seismic intensity for Friuli and Ancona, Italy, and the Alpide Belt

Bulletin of the Seismological Society of America ◽

10.1785/bssa0710061993 ◽

1981 ◽

Vol 71 (6) ◽

pp. 1993-2009

Author(s):

C. Chiaruttini ◽

L. Siro

Keyword(s):

Standard Error ◽

Strong Motion ◽

Total Sample ◽

Seismic Intensity ◽

Standard Errors ◽

Motion Data ◽

Horizontal Acceleration ◽

A Value ◽

Significant Difference ◽

Site Dependence

Abstract A new sample of strong-motion data has been analyzed in this paper: namely 120 records from the 1976 Friuli earthquake, 40 from the 1972 Ancona swarm, and 64 from different Alpide Belt shocks. The sample is the result of the selection of peak recorded horizontal acceleration of every three-component record greater than 0.015 g. Linear regressions were applied to the data with the purpose of understanding the geography and the site-dependence. Separate analyses have been carried out, firstly taking into account acceleration (a), magnitude (ML), and distance (d), then computing a - IMM relationships and comparing the respective standard errors of the estimates. Finally, a - ML - d - IMM regressions for the total sample from Friuli, Ancona, and the Alpide Belt have been computed. The main result are The Friuli data are 70 per cent lower than those of the Alpide Belt and Ancona. The Ancona set of data is closely related to the Alpidic set, at a magnitude level of 4.0. The expected accelerations in Friuli are close to the average values recorded in the Circumpacific Belt region (intermediate earthquakes excluded), while the Alpide Belt accelerations are close to the Circumpacific maxima. Site-dependence between data recorded in Friuli on thick consolidated alluvium (ThA) and on rock-like (RI) is not statistically significative. Friuli sites with thin alluvium (thA) exhibit stronger average accelerations and a significant difference in the ML coefficient (which is 0.47, with a standard error of 0.05) as regards the RI + ThA category (which has a value of 0.35, with a standard error of 0.04). The standard errors of the estimates of the regressions a - IMM in the case of Friuli and the Alpide Belt are close to the corresponding standard errors of the regressions a - ML - d. It may be concluded that a - IMM correlations are, in some cases, a valuable tool for seismic risk estimations, especially for being able to use the historical information.

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The July 17, 2011, ML 4.7, Po Plain (northern Italy) earthquake: strong-motion observations from the RAIS network

Annals of Geophysics ◽

10.4401/ag-5389 ◽

2012 ◽

Vol 55 (2) ◽

Author(s):

Marco Massa ◽

Paolo Augliera ◽

Gianlorenzo Franceschina ◽

Sara Lovati ◽

Maria Zupo

Keyword(s):

Ground Motion ◽

Strong Motion ◽

Response Spectra ◽

Site Amplification ◽

Northern Italy ◽

Po Plain ◽

North West ◽

The North ◽

Strong Motion Network ◽

Seismic Wavefield

On July 17, 2011, at 18:30:23 UTC, a ML 4.7 earthquake occurred on the east side of the Po Plain (northern Italy), between the towns of Ferrara and Rovigo. The epicentral coordinates provided by the National Earthquake Center of the Istituto Nazionale di Geofisica e Vulcanologia (National Institute of Geophysics and Volcanology, INGV) were 45.01˚N and 11.41˚E (http://iside.rm.ingv.it/iside). The depth of the hypocenter was constrained at 8.1 km, corresponding to a buried active source that existed in the area. The source of the event was characterized by a predominant left-transverse focal mechanism, even if there was also an important reverse component. Although it did not produce relevant damage, the earthquake was clearly felt in an area of about 50 km radius around the epicenter. The maximum observed intensity was V on the Mercalli-Cancani-Sieberg (MCS) scale, with a predominant distribution of damage towards the north-west. This study provides an overview of the strong-motion waveforms of the mainshock as recorded by the RAIS (Rete Accelerometrica Italia Settentrionale) strong-motion network, in particular focusing on the recordings provided by the stations located in the central part of the basin, which were installed in correspondence with hundreds of soft sediments. The preliminary results show the relevant influence of the basin on the seismic wavefield, highlighting in particular a possible site-amplification phenomena, and also affecting the ground motion at long periods (T >1 s). The systematic underestimations provided by the empirical ground-motion predictive models calibrated for Italy in terms of acceleration response spectra up to 2.0 s support this hypothesis. The sharing of the 24 waveforms (in raw sac and ascii formats) recorded by RAIS is assured by the availability of the data at the ftp site: ftp://ftp.mi.ingv.it/download/RAIS-FR_rel01/.

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Engineering implications of ground motions from the Northridge earthquake

Bulletin of the Seismological Society of America ◽

10.1785/bssa08601bs270 ◽

1996 ◽

Vol 86 (1B) ◽

pp. S270-S288 ◽

Cited By ~ 2

Author(s):

Susan W. Chang ◽

Jonathan D. Bray ◽

Raymond B. Seed

Keyword(s):

Site Response ◽

Ground Motions ◽

Free Field ◽

Strong Motion ◽

Site Amplification ◽

Northridge Earthquake ◽

Horizontal Acceleration ◽

Predictive Relationships ◽

Stiff Soil ◽

Maximum Horizontal Acceleration

Abstract The magnitude, duration, and frequency content of ground motions from the Northridge earthquake are analyzed and compared to predictive relationships typically used in engineering design and to the 1994 Uniform Building Code (UBC). A relationship between maximum horizontal acceleration on soil versus maximum horizontal acceleration on rock is presented based on strong-motion recordings at free-field sites. The effect of geologic conditions on localized damage patterns is shown to be important for this earthquake, although many of the sites within the affected region are stiff soil sites classified as S1 or S2 sites by the UBC. The results of preliminary seismic site response analyses performed at two deep alluvial sites indicate that much of the observed site amplification can be captured by one-dimensional wave propagation analyses.

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