We were away for the recent magnitude 5.3 earthquake which was centred only a few kilometres from here, so it was with some trepidation that we inspected our house and observatory upon arriving home yesterday. I'm glad to report that there appears to be no damage to the observatory, and apart from smashed china ware, vases and ornaments; plus books and pictures on the floor, everything seems to have survived.
Before arriving home, I was concerned that the approx 100 kg of mass on the 3 metre pier might have tested the pier-foundation interface beyond the limit, or, that the building itself may have bashed into the upper part of the pier via the edge of the hole in the observing floor (which is about 2.2 metres above ground level). This appears not to have been the case since the electrical cables that pass through the narrow (~5 - 10 mm) gap do not apear to be marked at all. Whew!
I've just checked the polar alignment and it has moved a small amount in an Easterly direction, which is interesting, since most of the stuff affected in the house also moved in an E-W direction too.
I now think that the 188 kg of reinforcing steel that I put into the pier foundation, along with the 2 cubic metres in the block, and the 450 mm dia concrete pier were all well worth it! After all, who designs their observatory for an earthquake?
Chris
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