Hi Michael. The creep meters for the most part are at the surface. However the strain and tilt meters are much deeper. In order for them to be accurate they have to be placed in unfractured bedrock. The ones in SJB are at a depth of about 200 meters.

There are various type of creep meters and some are used in conjunction with others. As an example these are the ones used along the Hayward fault.

Fremont Winery Creepmeters, CFW1 and CFW2 are located in the old winery in Fremont on Osgood Road; these creepmeters are two separate instruments. CFW1 uses helical piles as anchors. The helical piles consists of 2 or 3 rods that are "augared" or "screwed" obliquely into the ground to a depth of approximately 10 meters. At the surface, the rods are welded together and attached to the creepmeter sensors. CFW2 uses a concrete piers as anchors. In the future, the motion of the top of the concrete pier relative to the base of a borehole can be removed with periodic inclinometer measurements in the borehole (to 30 meters depth).

Hayward Creepmeter, CHP1 and CHP2. These creepmeters use common helical piles but have individual sensors. CHP1 uses a magnerule sensor while chp2 uses a more traditional lvdt to measure displacement. This instrument is located on Palisade street near Mission Blvd in Hayward.

Temescal Park, CTMS is located in Temescal Park in Oakland, this instrument uses helical piles as anchors. There was offset in early 1996 due to heavy rainfall, which flooded the instrument. That is always a problem.

Point Pinole, CPPS is located in Point Pinole Regional Park at the north end of the Hayward fault and this instrument uses helical piles as anchors.

As you can see they are trying to cover all the bets, but it is still nothing more then observing and noting what is seen and what happens. I still think though that the best assessment of creep is the number of quakes over a wide range of depths along a given section of a fault that will give the best information about creep. The Hayward fault is a good example of this. The northern section of the fault has the same of creep from top to bottom. This was determined by radar data collected by the European Space Agency (ESA) ERS-1 spacecraft in June of 1992 and November of 1995 and by ERS-2 in September of 1997. You can click on the link below to see the full text in regards to this.

Now I have a question for you. You will note that that data for the Bay Area indicates the cfw1 data is a right lateral movement and chp2 data to the north of there indicates a left lateral movement. Any ideas as to how the fault may be moving in two different directions at the same time? Take Care…Don in creepy town.