抄録
Seismic refraction profiles using a large airgun on land were shot at the Kamafusa Dam area, Miyagi Prefecture, Japan, in 1985. Data from two 13-km-long airgun profiles and a quarry explosion profile were processed through stacking and filtering. A two-dimensional ray tracing method was applied to explain the data. The obtained upper crustal structure is composed of three layers with P-wavespeeds of about 2.6-3.0, 4.0-4.2, and 5.5 km/s. The configuration of the interface between the upper two layers is similar to the basement depth deduced from the published gravity data.
We also observed the same airgun data at several telemeter network stations and could record the signals transmitted over 60 km. This experiment demonstrated the feasibility and effectiveness of using an airgun on land in upper crustal structure investigation.
