Romanian surface-depth focal mechanism catalogue
Description
Parameters of the focal mechanism catalog for Romania surface-depth earthquakes (2005-2024). This catalog reports the following parameters: date (year/month/day), time (hh:mm:ss), Lat (latitude north, in degrees) and Long (longitude east, in degrees), Depth (km), Mw (magnitude), Strike1, Dip1 and Rake1 (strike, dip, rake of the first fault plane, in degrees), Strike2, Dip2 and Rake2 (strike, dip, rake of the second fault plane, in degrees), P-a, P-p, T-a, T-p ( P and T axis, azimuth and plunge angle, in degrees), Nr P (number of polarities), Err P (polarity errors), Method_Index (focal mechanism determination method: FOCMEC=1, FPFIT=2).
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Steps to reproduce
Focal mechanism solutions were obtained using a dataset of relocated events, where hypocenters were manually picked and relocated using Seisan (Hypocenter code / Seisan software; Havskov and Ottemöller, 2020) and Antelope (dbgenloc; brtt.com). The catalog includes focal mechanisms determined based on P-wave first-motion polarities, using two different software tools: FOCMEC and FPFIT. The selection of software depended on data availability and processing conditions. Seisan Processing (Method_Index 1): Earthquakes analyzed with FOCMEC were relocated using Seisan, and their focal mechanisms were determined using the FOCMEC code (Snoke et al., 1984), integrated into Seisan (Havskov and Ottemöller, 2020). Each solution was derived from at least seven observations. Antelope Processing (Method_Index 2): Earthquakes analyzed with FPFIT were relocated using Antelope’s dbgenloc module, and their focal mechanisms were determined using the FPFIT code (Reasenberg and Oppenheimer, 1985). This method applies a grid search algorithm to derive solutions from P-wave first-motion polarities (pubs.usgs.gov). FPFIT is integrated into Antelope, a seismic data processing system developed by Kinemetrics (kinemetrics.com), which provides tools for seismic data acquisition, event location, and focal mechanism analysis. Both FOCMEC and FPFIT were applied in this study, with software selection based on data availability and processing workflow. This systematic approach ensured consistency in determining focal mechanisms within the catalog.