Analysis of the local seismic hazard for the stability tests of the main bank of the Po River MARTELLI L., SEVERI P., BIAVATI G., ROSSELLI S., Regione Emilia-Romagna CAMASSI R., ERCOLANI E., INGV, Bologna MARCELLINI A.,TENTO A., GEROSA D., CNR - IDPA ALBARELLO D., GUERRINI F., LUNEDEI E., PILEGGI D., UniSi- DST PERGALANI F., COMPAGNONI M., PoliMI – DIS FIORAVANTE V., GIRETTI D., UniFE-DIC The embankment of the Po is a structure of strategic importance for the purpose of civil protection and urban planning. For this reason, the Po River Basin Authority (AdB Po) has received national funding to value the stability of the embankments under seismic conditions in the municipalities characterized by the highest seismic hazard. According to the Italian seismic classification (OPCM 3274/2003), the municipalities with the highest seismic hazard, in the interest tract, are: Boretto, Gualtieri and Guastalla in the Reggio Emilia Province, Carbonara Po, Sermide and Felonica in Mantua Province, Bondeno, Ferrara and Ro in Ferrara Province for an extent of around 90 km . All these municipalities are in the right riverside. STUDY AREAS (Mantua Province) Carbonara Po, Sermide, Felonica Boretto, Gualtieri, Guastalla (Reggio Emilia Province) Bondeno, Ferrara, Ro (Ferrara Province) The study was conducted in the From Seismic Hazard Map of Italy, INGV 2004 municipalities with the highest seismic hazard (PGA, Tr=475 y, damping=5%, according to the italian seismic classification) The ADOPTED PROCEDURE is derived from a previous study for the control of stability under seismic conditions of the expansion areas of some tributaries of the Po. Geological, geophysical and seismotectonic investigations were carried out: Definition of the geological and geophysical models: •collection and analysis of previous data (from public authorities and professionals); •review of seismic profiles (ENI courtesy) for the identification of the main tectonic structures and seismic-stratigraphic layers; •new in situ tests; •monitoring of ambient vibrations; •reconstruction of more than 100 geologic cross-sections, along significant transects based on geological characteristics, vulnerability conditions and urban exposure; •summary of the above-mentioned surveys to define the seismic bedrock. Definition of the input motion for the numerical analyses: The selected recorded accelerograms derive from two response spectra target (using Italian and European data-bases): • by national code (NTC 2008) TR 475 and 975 years • by a specific site hazard analyses: • review of the earthquakes catalogs; • identification of a magnitude distance couple; • identification of the reference responce spectra. Geotechnical laboratory tests (coordinated and performed by AIPO, Parma University and Turin Polytechnic Institute laboratories) Site seismic response tests through 1D numerical analyses Previous data 24 piezometers 50 m (continuous core New data drilling) 16 piezometers 10 m 20 DH 30 m (continuous core drilling) 6 DH 50 m (continuous core drilling) 3 CH 150 m (continuous core drilling) 299 CPTU 10 SCPT 3 seismic refraction profiles + Re.Mi. and MASW 10 electric profiles geological cross-sections in 98 perpendicular the Reggio Emilia Province cross-sections 9 longitudinal cross-sections geological cross-sections in the Mantua and Ferrara Provinces Examples of geological cross-sections Synthesis of the geological model in the western area sea level Sand with pebble Silt and clay - 100 m sea level Deep geologic cross-section alluvial between Boretto and Guastalla sediments (Reggio Emilia Province) - 500 m marine substratum Synthesis of the geological model in the eastern area Sand Upper Pleistocene-Olocene alluvial sediments Silt and clay Miocene marl Deep geologic cross-section along the bank in the Ferrara Province As a whole single station ambient vibration measurements (HVSR approach) were carried on at 160 sites along river sides between Carbonara Po (MN) and Ro (FE). At each site, two 20 min session measurements were performed (on the river embankment and at its foot) In general, two main HVSR peaks were detected as the possible effect of two main seismic interfaces at depth Carbonara Po Ficarolo Occhiobello Canaro <600 m/sec 1200>Vs>800 m/sec >1200 m/sec Casaglia Joint inversion of HVSR curves constrained by available down-hole results for shallower depths were carried on with Genetic Algorithm technique Reggio Emilia Province Seismic bedrock Vs < 600 m/s - 85 m Vs > 800 m/s Ferrara Province tract of interest Mantua Province tract of interest Vs < 600 m/s Vs < 600 m/s - 120 m - 160 m Vs > 1200 m/s Vs > 800 m/s Miocene marl Marine sediments (Lower Pleistocene) Marine sediments Vs > 1200 m/s (Lower Pleistocene) tract of interest Identification of the used accelerograms 500 500 DATASET 1 – Tr 975 anni SPR7_006239ya DATASET 1 – Tr 475 anni SPR7_006239ya 450 SPR7_006239xa 450 SPR7_006239xa SPR7_005826xa SPR7_005826xa 400 SPR7_000368xa 400 SPR7_000368xa SPR7_000055xa SPR7_000055xa 350 SPR7_006270ya 350 SPR7_004675ya SPR6_006275ya SPR6_006275ya ) 300 ) 300 2 SPR6_006239ya 2 SPR6_006239ya SPR6_000368ya SPR6_000368ya 250 250 SPR6_000368xa SPR6_000368xa 200 SPR6_000055xa 200 SPR6_000055xa PSA (cm/s PSA SPR6_007059xa (cm/s PSA SPR6_007059xa 150 SPR4_000055xa 150 SPR4_000055xa SPR4_006275ya SPR4_006275ya 100 SPR4_006239ya 100 SPR4_006239ya SPR4_000368ya SPR4_000368ya 50 SPR4_000368xa 50 SPR4_000368xa SPR4_007059xa SPR4_007059xa 0 0 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 Periodo (s) Periodo (s) 500 500 DATASET 2 SPR_AMB_DEV_ DATASET 3 450 1_000604xa 450 GuastallaM_R_00 6345xa 400 400 SPR_AMB_DEV_ 1_000603ya 350 350 GuastallaM_R_00 ) ) 300 SPR_AMB_DEV_ 300 0046ya 2 2 1_000382ya 250 250 SPR_AMB_DEV_ 200 1_000382xa 200 GuastallaM_R_00 PSA (cm/s PSA (cm/s PSA 0046xa 150 150 SPR_AMB_DEV_ 1_000364xa 100 100 GuastallaM_R_00 50 SPR_AMB_DEV_ 50 6345ya 1_005089ya 0 0 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 Periodo (s) Periodo (s) Identification of the sismo-stratigraphic columns DH7 Rifrazione CH-Boretto MASW REMI Valori medi DH9 SCPT17bis Valori medi Vs (m/s) Vs (m/s) MACROAREA GUASTALLA 0 100 200 300 400 500 600 700 800 900 0 100 200 300 400 500 600 700 800 Sez1 Sez2 Sez5 Sez6 Sez7 Sez9 Sez11 Sez13 Sez15 Sez16 Sez19 Sez21 Sez22 Sez23 SEZIONI Sez3 Sez8 Sez10 Sez12 Sez14 Sez17 Sez18 Sez20 0 0 Sez4 DH riferimento DH2 DH7 DH9 DH14 DH15 DH16 DH19 DH24 10 Z (m) Z (m) 1 1 5 287 263 20 2 S16GS-1 2 3 371 S15GS-3 3 30 4 259 243 4 10 287 263 5 371 263 5 40 371 6 287 6 50 15 7 7 Z (m)Z Z (m)Z 8 8 287 259 301 60 9 9 20 10 S07BR-3 10 70 11 371 287 11 287 12 12 80 13 13 25 371 14 14 90 371 15 15 100 30 16 16 17 S16GS-2 17 18 18 19 19 DH15 SCPT17 Valori medi DH24 SCPT25 Valori medi 424 20 20 Vs (m/s) Vs (m/s) 21 21 0 100 200 300 400 500 600 700 800 0 100 200 300 400 500 600 700 800 22 22 23 S07BR-4 23 0 0 24 S06BR-1 24 25 25 26 26 462 5 5 27 27 28 28 29 422 323 29 424 489 462 10 10 30 462 30 31 434 31 32 32 15 15 33 33 Z Z (m) Z (m) 434 424 424 422 467 34 34 489 35 S06BR-2 35 20 20 36 36 37 37 38 38 25 25 39 39 40 424 40 41 S16GS-3 41 30 30 42 42 43 43 DH DH2 DH7 DH9 DH14 DH15 DH16 DH19 DH24 44 44 Sezione Sezione 3 MEDIE Sezione 7 MEDIE Sezione 11 MEDIE Sezione 13 MEDIE Sezione 15 MEDIE Sezione 16 MEDIE Sezione 19 MEDIE Sezione 22 MEDIE 45 S06BR-3 45 Sondaggio S2BR S7BR S9GL S14GL S15GS S16GS S19GS S24CP Z (m) 46 489 46 1 94 47 47 2 121 48 424 48 3 160 49 49 153 4 160 50 50 5 189 51 51 6 194 52 52 7 251 263 237 239 262 53 53 8 347 337 312 287 158 258 346 424 9 335 369 203 285 176 223 243 262 54 54 10 243 351 245 259 243 438 174 225 218 55 55 11 302 270 241 302 320 316 268 272 263 56 56 12 295 345 292 264 173 284 302 215 57 S06BR-4 57 13 246 387 244 246 240 344 264 241 58 58 287 14 225 405 371 359 289 240 358 252 274 59 59 15 307 391 388 260 289 459 316 275 60 60 16 275 426 599 275 253 362 290 364 333 61 61 17 309 410 538 291 248 278 425 328 427 301 62 62 18 329 380 378 379 248 364 300 544 19 447 366 490 283 207 489 329 429 63 434 434 424 424 422 422 467 489 489 323 462 462 462 63 20 342 292 300 310 255 319 353 430 64 64 21 493 301 366 276 341 353 330 323 450 65 65 22 413 331 381 422 331 269 396 342 520 66 66 424 23 494 331 494 311 301 381 367 451 462 351 67 67 24 413 368 494 382 342 381 342 521 434 68 68 25 496 293 255 368 431 343 397 451 69 69 26 398 302 368 414 431 332 368 432 70 70 27 414 432 382 451 451 414 277 551 489 71 71 28 452 414 368 398 467 451 382 249 433 424 29 415 415 496 523 551 398 356 433 72 72 30 433 433 523 552 619 497 369 498 73 73 31 383 74 74 32 474 75 75 33 356 76 76 34 312 77 77 35 433 78 78 36 344 79 79 37 415 80 80 38 LEGENDA 622 444 600 600 600 600 600 600 600 600 600 600 600 600 600 600 39 710 81 81 40 Corpo arginale non analizzato 434 82 82 41 554 83 83 42 Prevalentemente limi sabbiosi 525 84 84 43 357 85 85 44 Prevalentemente argille e limi 475 45 333 46 Prevalentemente sabbie 416 47 434 48 525 49 416 50 454 Identification of the geotechnical parameters Depositi prevalentemente limoso-argillosi PARMA Depositi prevalentemente limoso-argillosi PARMA Guastalla - Lab.