Thursday last week I spent a day in the Coastal Range of Northwest Oregon near Portland installing a post-hole seismic sensor as part of the Oregon Hazards Lab management of resources in Oregon for the Pacific Northwest Seismic Network. This was a combination sensor that captures large events quickly and small events with high resolution.
While the title of this post was created in jest, there is some truth to it. These post hole sensors are buried a couple meters below the surface inside a tube, with the cap of the tube flush with the surface or raised only slightly above the surface. Additionally these sensors can sometimes be placed several meters away from the control and communications equipment protected by a large environmentally sealed box and set on a concrete platform. The lead technician who I accompanied told several stories of post-hole sensors that were damaged by heavy equipment because they were not so obvious to the operator. This sensor was marked by a small wall of cement blocks.
This site was setup in 2017 and operated until August 2020. We relocated the original sensor to another site in Oregon to terrain for which it was better suited. A new sensor was purchased for the install that has better performance characteristics for the terrain type at this location than the previous sensor. While at the site we performed a communications equipment upgrade and made modifications to reduce noise caused by environmental conditions.
Overall it was a very good day with beautiful autumn weather! I hope to do this again soon.
