Engineering Bedrock gen.

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Здравствуйте, все

Помогите с термином, пожалуйста. Не знаю, как называются по-русски "Seismic Bedrock" и "Engineering Bedrock" (сейсмичная и инженерная порода?)

Контекст:
As the shear wave velocity of upper earth crust is as homogeneous as from 3000 to 3500 m/sec, the upper interface of the upper earth crust having 3000 m/sec of the shear wave velocity is called "Seismic Bedrock".

In the viewpoint of Earthquake Engineering, it has been proposed, based on the followings, to use the shallower interface of which underlying stratum has from 300 to 700 m/sec of the shear wave velocity. This interface is called "Engineering Bedrock".

Спасибо