The geologic classifications are drawn from the NZ qmap - https://www.gns.cri.nz/Home/Our-Science/Land-and-Marine-Geoscience/Regional-Geology/Geological-Maps/1-250-000-Geological-Map-of-New-Zealand-QMAP/QMAP-text-maps
These are then mapped into Ahdi's 18 categories:
G01 Peat
G04 Artificial fill
G05 Fluvial and estuarine deposits
G06 Alluvium and valley sediments
G08 Lacustrine (including glaciolacustrine)
G09 Beach, bar, dune deposits
G10 Fan deposits
G11 Loess
G12 Glacigenic sediments (drift and outwash)
G13 Flood deposits
G14 Glacial moraines and till
G15 Undifferentiated sediments and sedimentary rocks
G16 Terrace deposits and old alluvium
G17 Volcanic rocks and deposits
G18 Crystalline rocks (igneous and metamorphic)
G07 and G13 were distinguishing between fine and coarse floodplain deposits. There is difficulty distinguishing between the two based on NZ surface geology metadata so these were both merged to G13.
G02/G03 were categories made for a specific river in North America hence these categories are not of use in NZ.
The resultant classification is:
MODEL_AhdiAK_geologyclassifications.csv
This file outlines mappings between each qmap geologic category (~3000 entries) and the Ahdi categories outlined above
The code that was used to make this classifications is as below.
Andrew and I (Jason) identified a few inconsistencies in the classifications and this will need updating.
Parameter based vs30 dependance
G06 / G13 has a distance to coast factor applied with increased vs30 as the distance to the coast increases.
G13: <8km; 197 . >8, <20km, 197-500 (linear); >20; 500
G06: <8km; 240 . >8, <20km, 240-500 (linear); >20; 500
G04 / G05 / G06 / G09 has a slope based factor.
These correlations were identified by using a least-squares fitting with a 95% confidence interval
Plots based on current measured dataset
Notes / things to check:
- Prior model for G13 is averaged between G07 and G13 as the two categories are merged.
- Update the categorisation to a python-based code
- Consult with a Geologist as needed
- Get a student to go through the updated list and check the classifications on a line-by-line level make sense