Seismograph – Part 4

Made the last physical change to reduce the urban noise this past weekend.
We did a speed read of the USGS seismic vault construction guideline, you can pull it down and check it out here; https://pubs.usgs.gov/of/2002/ofr-02-0144/ofr-02-0144.pdf

In short, they recomend a bunch of things that I cant come at, either size wise, or cost wise.
We tried to take the guts of the vault and reproduce it in the backyard.

One thing to note from the recommendations, we don’t have to worry about the thermal aspects of the vault since the Raspberry Pi seismograph is not adversely affected by temperature changes.

This is the big picture. We are going to dig a hole, put some cement in the bottom, stick the plastic bucket into the hole – grounding it in the wet cement – then put some more wet cement in the bottom of the bucket, then put a plate (USGS said glass, bit short on that so using some steel) on the cement and that’s hopefully that.

So, lets get going…..

Hole dug, and wet cement in the bottom.
As per the PDF, we put a mound in the middle then pushed the tub down and settled it.

It probably did not matter much, but we made sure it was level in both directions.
The USGS said that we should put wet cement around the whole bin, but I was short on cement, so we just left it at the bottom. We could get some more and put it around the whole thing at a latter date, but, well, lets see how things go with just the bottom stuck down.

Wet cement in the bottom, the plate on top and leveled in both directions.

The Raspberry Pi setup is the same. I did not feel the need to change anything in this regard.
The Ethernet brings both network and power. The POE adapter splits it off and routes it to the appropriate port.

The fake rock is just sitting there for now, but the plan is to dig it in a little around the edge, put some sort of edging around to ‘seal’ the ‘rock’ to the ground and thus tub.
We are planing a small garden around the corner of the retaining wall, both to ‘hide’ the rock a bit, but also to finish that part of the lawn, the grass never grows all that great, probably due to the grape fruit tree shade.

The fake rock and tub are not the best, I like the seal on the old bucket better, but it was just too small and shallow. We could not find a longer one with the same seal, so we just have to make do.
The big issue is bugs. A close second is water/moisture.

So, the 300 dollar question, how is the urban noise?
Duno. Its only been in place a few hours Sunday afternoon, we need to watch it for 2-3 days at the very least to get a feel for things.
Don’t forget that you can view its almost live output here; http://thebaldgeek.net/index.php/seismograph/


One Response to Seismograph – Part 4

  1. Ok – reading the specs for the first time, two points jumped out for me.

    One – the hole is not all that big, and is quite possible to dig by hand.

    But point two is the hurdle. The pit is lined with a LOT of concrete. 100 cubic feet,
    or over 12,000 lb.

    That’s a problem – but it make sense.

    Blow on a leaf and it moves. Blow on a few tons of concrete and it doesn’t.

    I can see it acting as a dampener to cancel out the “local” background noise.