Pacific Northwest Geodetic Array
Central Washington University

Slow Earthquakes in the Pacific Northwest

Installation of Mt. Vernon Tiltmeter

We completed installation of the second Cascadia long-baseline tiltmeter near Mount Vernon, WA in July 2005 on the grounds of the Washington State University Research Extension Center. Director Debra Inglis facilitated the permissions and locations of this tiltmeter installation on this agricultural research property. The north-south arm is 1,647ft in length and the east-west arm is 1,580ft. This system was particularly difficult to build due to the presence of a Skagit River flood plain. The site was chosen for the extent of relatively flat ground and the willingness of the WSU staff.

Mount Vernon Pipe Laying WSU Research Extension


Tiltmeter Installation
Pipe in the ground
Setting Cover
Setting Cover
Setting Cover
Exterior Electronics Box

This tiltmeter has no center vaults and is an inverted "T" in plan view. The data logger is stored 1 km away in a maintenance shed. All electronics have been installed in exterior boxes due to the poor drainage of the site. The large hydrological signal is greatly depressed in the tilt calculation illustrating the benefit of long length.

Helicapiles and covers
Electronics Housing
Helicapiles and covers
Map View of Pipe Location

Data stored in the computer are accessed via cell-phone through the internet. Power to the tiltmeter comes through an AC hookup (120V at 0.2 Amp is equivalent to a 25W light bulb).