Two geodetic stations, the positions of which are frequently monitored by geodetic distance-measuring techniques, were located 5 and 10 km from the epicentral area of the Briones Hills earthquake swarm (maximum magnitude ML = 4.3) of January 1977. Although a 10 μradian postearthquake tilt change was recorded at a nearby tiltmeter, no significant change in geodetic distances could be detected at a sensitivity of at least 0.5 ppm. A simple dislocation model of the main earthquake in the swarm would predict no observable change in either tilt or geodetic distance.

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