Information for Strong-Motion Station
Half Moon Bay - Hwy 1/Tunitas Cr. Bridge
CGS - CSMIP Station 58754
Earthquakes recorded by this station
(Station Photograph - click to enlarge)(Sensor Layout - click to see PDF File)
Latitude 37.3574 N
Longitude 122.3970 W
Elevation (m) 16
Site Geology  
Vs30 (m/sec)  
Site Class  
No. of Spans6
Plan ShapeCurved with skew.
Total Length420.5' (128.2m). Bridge spans range from 65' (19.8m) to 75' (22.9m) long.
Width of Deck34' (10.4m)
Construction Date1962
Instrumentation1997. 6 accelerometers on the bridge. 3 accelerometers at a free-field site.
Superstructure TypePrestressed concrete I-girders. Diaphragm abutments.
Substructure TypeRectangular concrete columns (retrofitted with steel jackets). 1 column per bent.
Foundation TypeThe taller bents (Bents 3 and 4) are on spread footings. Other bents and abutments are on steel piles.
RemarksThis bridge was instrumented under the interagency agreement between Caltrans and DOC. The bridge was retrofitted in 1994.