1832RE: [ai-geostats] variogram analysis
- Dec 7, 2004Usually when I've seen a "wavy" semivariogram, it's because of a local
feature superimposed over an existing field function - for instance, a
release of mercury in a field of soil with very low "natural" mercury
content. The period of the waviness is related to the distance across
the feature (the width of the spill, in this case). Of course, this is
nothing particularly earth-shattering, but useful none the less.
I've used semivariograms like this in the past to "guestimate" the
approximate size of a plume based on sparse data. Not all geostatistics
ends up in gridding and estimating at every point! Sometimes just
looking at the semivariogram is very useful.
Senior Environmental Scientist - Geochemistry
MACTEC Engineering and Consulting, Inc.
Kennesaw, Georgia, USA
From: Rajive Ganguli [mailto:rajive.ganguli@...]
Sent: Tuesday, December 07, 2004 4:50 PM
Subject: [ai-geostats] variogram analysis
My question is general. What do you conclude if your variogram is
wavy? Cyclic patterns? I have what appears to be high nugget,
followed by a wavy pattern.
If you wish, here is more info: an offshore placer platinum deposit,
not too many boreholes - just 29 from decades ago spanning several
square kilometers. The variogram (from GEOEAS) of the grade (ln) is
The variogram is cyclic. Goes up and down. I tried various
I will try to dig up the geological information and see what it says.
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