Strain data from the Benioff type gauge installed in the Kipapa Tunnel on Oahu, Hawaii, are analyzed for the period February 1964 to May 1978. The predominant response is due to temperature variations and rainfall. A rainfallstrain transfer function is obtained using rain water infiltration and groundwater recession models developed by hydrologists. Numerical values obtained range from 0.27 to 0.53 × 10−7 strain/inch of rain (at a nearby rain gauge).
Subtracting expansion of the quartz rod due to temperature variation, the linear expansion coefficient of in situ tholeiitic basalt of 32 × 10−7/°C is obtained.