Appendix D. Focal mechanism solutions.
Nine events located near by CROP03 profile (Fig. 17) have been analyzed based on regional waveforms recorded by broad-band stations from surrounding countries. The source parameters have been retrieved using a robust methodology (INDirect PARametrization) to stabilize the inversion of a limited number of noisy records. This methodology is particularly important for relatively weak events, where the presence of seismic noise and the small number of stations makes difficult the analysis of the events. The source mechanisms obtained are consistent with the active tectonic processes and the complicated structure in the Northern Apennines. The detailed information for the focal mechanisms are given in Table 6 and the solutions and their errors are shown in Fig. 24.
Table 6. Focal mechanisms solutions
| ID No of event | Date (dd/mm/yyyy) | Time (hh:mm:ss.ss) | Lat (deg) | Lon (deg) | Depth (km) | Mw | M0 (Nm) | Nodal Planes (strike, dip, rake) (deg) | No of signals |
|---|---|---|---|---|---|---|---|---|---|
| 1 | 26/09/1997 | 00:33:12.25 | 42.90±0.19 | 12.88±0.19 | 3±3 | 5.6 | 0.332E+18 | 333 42 -57/112 56 -116 | 14 |
| 2 | 26/09/1997 | 09:40:26.90 | 43.01±0.01 | 12.82±0.02 | 3±1 | 5.8 | 0.619E+18 | 246 32 -36/7 72 -117 | 8 |
| 3 | 03/10/1997 | 08:55:21.50 | 43.10±0.10 | 12.90±0.20 | 20±1 | 5.2 | 0.913E+17 | 353 51 -56/126 50 -124 | 13 |
| 4 | 06/10/1997 | 23:24:52.50 | 43.06±0.12 | 12.80±0.13 | 27±1 | 5.5 | 0.288E+18 | 135 41 52/1 59 118 | 10 |
| 5 | 12/10/1997 | 11:08:36.30 | 42.81±0.06 | 12.93±0.087 | 5±2 | 5.2 | 0.861E+17 | 342 70 -78/131 23 -119 | 10 |
| 6 | 26/03/1997 | 16:26:11.50 | 43.07±0.05 | 12.80±0.14 | 50±20 | 5.5 | 0.262E+18 | 120 89 127/211 37 1 | 11 |
| 7 | 03/04/1998 | 07:26:36.60 | 43.18±0.01 | 12.79±0.02 | 10±1 | 5.2 | 0.402E+17 | 320 65 -86/130 25 -99 | 13 |
| 8 | 01/03/2008 | 07:43:16.20 | 44.00±0.26 | 11.36±0.02 | 20±1 | 4.7 | 0.125E+17 | 189 41 52/ 55 59 118 | 5 |
| 9 | 01/03/2008 | 08:43:50.70 | 44.25±0.01 | 11.40±0.003 | 12±1 | 4.2 | 0.236E+16 | 263 78 175/354 85 12 | 11 |
| INPAR tested with depth prescribed to different intervals (see Fig. 19) | |||||||||
| 4 (2-10 km) | 06/10/1997 | 23:24:52.50 | 43.01±0.01 | 12.81±0.01 | 2±7 | 5.4 | 0.126E+18 | 229 21 -40/357 77 -106 | 10 |
| 4 (2-16 km) | 06/10/1997 | 23:24:52.50 | 43.06±0.04 | 12.80±0.01 | 16±13 | 5.5 | 0.232E+18 | 128 42 50/357 59 120 | 10 |
Figure 24. Focal mechanism solution
Results from the waveform inversion for the events listed in Table 6: focal mechanism with confidence areas.