Abstract
Ground strains caused by rainfall observed at Yura, Wakayama Prefecture from 1979 to 83 have been investigated. Strains due to rainfall reach their peaks within a few hours (we call them F type) or rather long time (S type) after peaks of rainfall intensity. The F type appears when rainfall amounts exceed 30-40 mm. Initial loss of rainfall (rainfall amount from the beginning to the time when its effect appears on the strain record) shows no clear seasonal changes though large initial losses are sometimes seen from summer to the end of fall. The lapse time between two consecutive rains does not affect the initial loss of latter rainfall except the case of small lapse times such as within one or two days. Effect of rainfall on the strain is large when its initial loss is small, so that initial loss is literally the loss which should be eliminated from total amounts of rainfall for analysis of strains caused by rainfall.
