Strain patterns along the Kaparelli–Asopos rift (central Greece) from campaign GPS data

<p>We present results from four GPS campaigns in the broader Kaparelli–Asopos area in central Greece. This area is undergoing extension as demonstrated by seismological, geodetic and geological data. The east-west striking Kaparelli normal fault ruptured during the March 4, 1981, M = 6.3 earthquake and created km-long surface breaks with the downthrown side to the south. The geodetic results include: determination of station coordinates in the ITRF 2005 frame, computation of station velocities with respect to stable Europe and strain rate tensor estimates. The pattern of velocities along the east-west direction (parallel to the rift axis; 40 km E-W × 12 km N-S) and azimuth of strain axes are compared to geological data and to other GPS results in central Greece. We find that strain in this region consists of an amount of shortening (66 ns/yr) in the direction approximately N 58°E, and about three times more extension (187 ns/yr) at N 32°W. A large change in strain orientation (from NW to NNE) is observed from west to east, along the active faults of Asopos rift in agreement with fault slip data. This change signifies the need for using local GPS networks to map local strain rate patterns in actively extending regions of Greece.