Having a Blast with Ocean Sonics Hydrophones!
Updated: Nov 13, 2020
Rawkstars of Science Video Series - Episode 2 features underwater explosive experts Alaska Seismic, who recorded the sounds of an underwater explosion in Statter Harbor, AK.
Statter Harbor in Juneau AK serves fishermen, charter operators, live-aboards, transient vessels, and pleasure yachts. Space is at a premium at this small,
but popular and busy harbor. The City & Borough of Juneau Docks and Harbors Division are in the process of improving the Harbor for commercial and private use. Plans include removing an underwater outcrop of bedrock to install additional floats.
Drilling and underwater blasting were performed as part of the Statter Harbor Improvement project in Auke Bay, Juneau, AK. Navigational improvements included dredging the Harbor basin and required blasting rock that could not be traditionally dredged or mechanically removed. In our latest video, you can watch the blast side by side with a playback of the acoustic recording as shown on Ocean Sonics Lucy software.
To access the submerged bedrock, crushed stone was placed over the rock to create a temporary work pad. Boreholes were drilled and loaded with explosives through casings in the fill material.
Project permits required a marine mammal monitoring program with watch zones based on species specific acoustic and pressure thresholds established by the National Marine Fisheries Service. An Ocean Sonics icListen hydrophone was deployed to record underwater sound during blasting for comparison with thresholds and watch zones.
Said Kristen Kolden of Alaska Seismic and Environmental, "After two blasts the bedrock obstruction was successfully removed with no sightings or reports of injured or distressed marine mammals. Underwater sound measured during blasting was lower than zone thresholds predicted by NMFS and will provide valuable data for future projects." To learn more about the methods used at this project, be sure and visit our partners at http://www.alaskaseismic.com/.