Page 25: of Marine Technology Magazine (Jan/Feb 2026)

Preparing the USGS Wave

Glider for launch aboard

California Polytechnic

State University Humbolt’s

R/V North Wind.

All images courtesy USGS nardyne Fetch transponders on the seabed. most extent of this zone.

Combining its known surface position with acoustic pulses They are part of a wider network along the Cascadia Sub- down to each Fetch transponder allows it to calculate the pre- duction Zone where subduction involves three plates, the Ex- cise position of each transponder – and therefore the position plorer, Juan de Fuca and the Gorda, sliding beneath the North of the seabed it’s sitting on. American Plate, creating the potential for magnitude 9+ earth-

By repeating these measurements over time, scientists can quakes and large tsunamis. track the movement of tectonic plates across faults to better The USGS GNSS-A sites, each with three Fetch transpon- understand and estimate earthquake and tsunami hazard. ders, are on the southernmost Gorda plate where the uncer-

One of the organizations using this technique to monitor sub- tainty of the Gorda plate motion relative to the North Ameri- duction zones, where one plate is sliding under another, is the can plate motion has implications on the size and recurrence

USGS. They