Explosive initiation system

A seismic detonation system for substantially simultaneously initiating a plurality of booster charges respectively disposed in a plurality of boreholes formed through the surface of a firing site and having respective borehole bottoms, the system comprising:

• an electric trunkline circuit disposed on the surface of the firing site and comprising a plurality of semiconductor bridge electric detonators connected therein, the trunkline circuit being connectable to a fire set capable of generating an electric signal in the trunkline circuit to fire the electric detonators;
• and
• a plurality of booster charges respectively disposed within a plurality of boreholes with at least one booster charge per borehole, the booster charges being respectively connected in signal-transfer relationship to contact portions of associated lengths of low-energy detonating cord, the lengths of low-energy detonating cord being substantially equal in length and extending from their associated booster charges through their associated boreholes to the surface of the firing site, the lengths of low-energy detonating cord being connected at the surface in signal transfer relationship to their associated electric detonators, whereby initiation of the electrically-initiated detonators by the electric trunkline circuit initiates the lengths of low-energy detonating cord which in turn initiate the booster charges.

A method of initiating one or more booster charges disposed in respective one or more boreholes formed in a blasting site, the booster charges being connected to the surface of the blasting site by one or more lengths of low-energy detonating cord which have contact portions disposed in signal transfer contact with their booster charges and which terminate in one or more surface sections of the low-energy detonating cord, comprises the steps of

• connecting the surface sections in signal transfer proximity to one or more electric detonators forming part of an electric trunkline circuit,
• connecting the trunkline circuit to a fireset capable of energizing the trunkline circuit to initiate the one or more electric detonators;
• and
• discharging the firing set whereby to initiate the one or more electric detonators which in turn initiate the one or more lengths of low-energy detonating cord which in turn initiate their associated booster charges.