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ShakeMap® Implementation in ItalyIstituto Nazionale di Geofisica e Vulcanologia: Michelini A., Faenza L., Lauciani V.
(Email: [email protected] [email protected] [email protected])
Observations: PGA, PGV andPSA response at 0.3, 1 e 3swith 5% damping all onhorizontal components
~ 260 Italian Stations totalincluding short period but notused for shakemaps
~50 Accelerometer
~140 Broad-band
Other stations
Vs30 SiteCorrections:classificationbased on adetailed geologymap of Italy[. Thegeology unitshave beengathered into fiveclasses,according to theEuroCode8provision.
References: Ambraseys et al. (1996), Earthquake eng. Struct. Dyn, 25,371-400; Bommer et al. (2000), Proceedings of the 12th World Conference on Earthquake Engineering, paper no. 207Carta Geologica d’Italia, scale 1:100000; Morasca et al. (2006), Journal of Seismology, 10, 351-333; Malagnini et al. (2002), Bull. Seismo. Soc. Am., 92, 6, 2186-2204; Malagnini et al.(2000), Bull. Seismo. Soc. Am. 90, 1062-1108; MPS Working Group(2004), http://zonesismiche.mi.ingv.it; Wald et al. (2006),http://pubs.usgs.ov/tm/2005/12A01/pdf/508TM12A1.pdf;Wald and Allen (2007), Bull. Seism. Soc. Am., 97, 1279-1395.
Acknowledgements: This research has been supported by the EU-SAFER project(contract n. 036935) and the INGV-DPC (2005-2007) project S4. The authorsthank the DPC for the data of the 1st of March Mugelllo sequence.
Ground Motion Predictive Equations (GMPEs):
a) Regionalization of the attenuation relationsfor M <5.5 events;
b) PGA for M ≥ 5.5 events adopts the relation ofAmbraseys et al. (1996) (light blue).
c) PGV for M ≥ 5.5 events adopts the relation ofBommer et al (2000) (light blue).
Colors in b) and c) match the zones in a).
a)
NEAlpsNWAlpsAppenines
b) c)
Discussion and ConclusionsSince October 2006, shakemaps have been published for188 M3+ events (http://earthquake.rm.ingv.it).
1. Data Acquisition and Processing: Currently, shakemaps are available within 15-30 minutes after an event, using a revised location In the near future, almost real-time shakemap will be generated automatically after an event (within 5/6
min).2. Testing the importance of the data:
The shakemaps have been found to be generally reliable. The results shown in Box A confirm an overalladequacy of the adopted GMPEs and local geology corrections when attempting to represent the trueground shaking.
The inclusion of the near field data (BOX B: INGV+RAN data) improved the detail of the shakemaps and theBIAS compensates for possible erroneous estimations of magnitude.
The test in BOX C, where no BIAS correction is applied, shows that the current GMPEs adopted tend tooverestimate the PGM near the epicenter.
The tests show that availability of dense strong motion station data are of much relevance whendetermining shakemaps and that the BIAS correction is important to compensate for incorrect initialmagnitude estimates.
Published shakemaps for M 3.0+ (188 evens since October 2006)
IMPLEMENTATIONThe March 1st, 2008, Mugello sequence of medium size events which occurred in Northern Apennines, featured three events withmagnitude 4+ and many smaller ones. In this example we report the results obtained from the analysis for the first event, with M 4.2(2008:03:01 08:43 MST).
BOX A: Comparison between the shakemaps processed with no observed data and with INGV stations only (red and purple triangles). The%Diff and the ΔPGX comparison indicators are small at the stations. The BIAS (a factor within ShakeMap® designed to minimize thedifference between the data values at the seismic stations and those predicted by the GMPEs and expressed in log scale) indicates a goodagreement (BIAS ≈1.0).
PROBLEM: the INGV stations are not in proximity of the epicenter.BOX B: Inclusion of the RAN data, the strong motion network operated by DPC (yellow triangles in the INGV+RAN data panels) showsrelevant differences in the near field with INGV+RAN data shakemaps having values as much as 30% higher than those with INGV dataonly. The BIAS in this case is also larger (1.37) and a possible explanation is given by an underestimation of magnitude. This could in factbe the case since moment magnitudes, Mw, determined in various ways, have always indicated values as large as 4.5 for this event.BOX C: shakemaps with M 4.5 imposing a BIAS=1( i.e., no BIAS calculation). %Diff and the ΔPGX show differences in the areas west and inproximity of the epicenter. For the amplifications to the west, this could be attributed to site effects not captured by the adoptedamplification correction. For the near-field differences, we observe that the ground-motion predictive relationships tend to over-estimatethe PGA, compared to the real shaking. This would imply that the adopted GMPEs while describing properly the attenuation at largerdistances have difficulties to account accurately for the near-field variability.
No Data - Scenario
Based on INGV data
No Data
Based on INGV dataBased on INGV data
Bias 0.98
!
"PGX = (PGXINGV # PGXNoData )
%Diff ="PGX
PGXINGV
$100
!
"PGX
= (PGXINGV
# PGXNoData
) BOX A
Based on INGV+RAN data
Based on INGV data
Based on INGV+RAN data
Based on INGV data
!
"PGX
= (PGXINGV +RAN # PGXINGV
)
Based on INGV data
Bias 0.98
Based on INGV+RAN data
Bias 1.37
!
"PGX = (PGXINGV +RAN # PGXINGV )
%Diff ="PGX
PGXINGV +RAN
$100
BOX
B
Based on INGV+RAN dataBased on INGV data
Based on INGV+RAN dataBased on INGV data
!
"PGX
= (PGXINGV +RAN # PGXINGV
)
!
"PGX = (PGXINGV +RAN # PGXINGV )
%Diff ="PGX
PGXINGV +RAN
$100
BOX C
NH5.4-A-07207
DATA ACQUISITION
The two panels on the left showthe new data feeding that will beimplemented at INGV
5 to 6 minuets are necessaryto process an event shakemap.The procedure is fully automaticand based on the EarthWormprocessing packages.
As more information (data andsource parameters) becomeavailable, updated shakamapsare generated automatically,
Similarly, the “manual”procedure allows for off-lineshakemap revision.
Shakemap generation at INGV :
The parametric PGM data are determined directly from thewaveforms assembled for each event in SAC format afterBacknet-Locator procedure.
Shakemaps are determined automatically after manual revision of thehypcenter location by the H24 on duty personnel (max 30 minutesand on average 15 minutes after the event) using an “in-house”procedure.
WORK IN PROGRESS (below):
ON-LINE: In-house procedure,manually revised locationscheck_new_data.shget_event_fromS4.shchk_WW.shcheck_shake_single.sh
ShakeMap
Backnet-Locator
DATA
WEBpublication
TESTING - THE IMPORTANCE OF REAL DATA
ABSTRAC: Since 2005, the Italian Civil Protection (Dipartimento della Protezione Civile, DPC) has funded several projects driven toward fast assessment of ground motion shaking in Italy.- the final goal being that oforganizing the emergency and direct the search and rescue (SAR) teams. Similarly, in mid 2006, the EU SAFER project aimed toward rapid assessment of ground motion shaking started. To this end, the IstitutoNazionale di Geofisica e Vulcanologia (INGV) has started to determine shakemaps using the USGS-ShakeMap® package within 30 minutes from event occurrence using a manually revised location.In this work, we present the INGV implementation of USGS-ShakeMap® for earthquakes occurring in Italy and immediately neighboring areas. Emphasis is put on adopted ground motion predictive relations, sitecorrection for the amplification of the ground motion and on fast procedures for data processing and the in-progress developments to determine near real-time shakemaps.Finally, a test on the fundamental role of observed data and of seismic station coverage is shown.
