On the reliability of focal plane solutions using first motion readings

• Published in: Journal of seismology Vol. 18; no. 1; pp. 181 - 197
• Main Author: Hofstetter, A.
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 2014; Springer; Springer Nature B.V
• Subjects: Earth and Environmental Science; Earth Sciences; Earth, ocean, space; Earthquakes; Earthquakes, seismology; Engineering and environment geology. Geothermics; Exact sciences and technology; Fault lines; Faults; Focal plane; Geophysics/Geodesy; Geotechnical Engineering & Applied Earth Sciences; Hydrogeology; Internal geophysics; Mathematical models; Natural hazards: prediction, damages, etc; Original Article; Perturbation methods; Planes; Plate tectonics; Polarity; Seismic activity; Seismic phenomena; Seismology; Stations; Structural Geology; Studies; Waveform analysis; Faulting; P wave onsets; Focal plane solution; models; orientation; reliability; normal faults; P-waves; velocity; earthquakes; quality; strike-slip faults; fault displacements; thrust fault; fault planes; stress fields; seismic waves
• ISSN: 1383-4649; 1573-157X
• DOI: 10.1007/s10950-013-9410-3

First motion fault plane solutions provide invaluable important information on the mechanism of seismogenic faults and the orientation of the local stress field. However, there are severe limitations and shortcomings regarding the reliability of the calculated solution and how accurately it reflects the real earthquake mechanism. In this study, we examine the dependence of the three mechanisms of ideal strike slip, normal, and thrust on different quality estimators, i.e., event location, velocity model, and reverse polarity stations. We intentionally perturb the original fault plane solutions by changing only one of the parameters that control the solution at a time and compare the perturbed solutions with the real one. Finally, we randomly perturb all the parameters for each earthquake in a large set of events. We then discuss the effect of the perturbations on the reliability of the solution.