GEODETIC OBSERVATIONS OF THE M-5.1 JANUARY 29, 1994 NORTHRIDGE AFTERSHOCK

Geodetic observations of the January 29, 1994 M 5.1 aftershock of the Northridge earthquake are consistent with seismic solutions Showing le ft-lateral Oblique slip on a northeast striking steeply dipping fault. Thirty second solutions of the data from the station showing the maxi mum observed displacement (35 mm) indicate neither precursory nor imme diate post-seismic motion to the aftershock. The aftershock does appea r to be superimposed over the longer term Northridge post-seismic defo rmation field. Inversions of the data yield a potency of 2.6 +/- 0.3 x 10(-3) km(3) slightly higher than that determined by seismic methods. Combining the potency with estimates of rigidity from P- and S-wave v elocities yields a moment that is consistent with seismic moment solut ions.