GTL

Geotechnical Layer (GTL) refers to material properties from surface to about 350m depth. GTL is known to have significant impact on local strong ground motions:

GTL for CVM-S4 with Perturbations

We plot standard maps and profiles for each CVM implementation. Two new versions are as follows:

• Profiles - This is the version that adds the Vs30 GTL on top of the Ricardo, En-Jui GTL idea.

• Profiles - This is the version that does the Ricardo, En-Jui GTL, but if that isn't applicable, it does the Vs30 GTL.

Previous GTL approaches

For reference, the original ideas are here:

• Profiles - CVM-S4.23 + Vs30 GTL

• Profiles - Ricardo, En-Jui idea

We note that the Salton Sea area looks weird in the RE GTL then Vs30 GTL variation. The reason for this is that the starting model was harder than the original CVM-S4 material properties, as such we use the original CVM-S4 Vs, Vp which are a lot firmer than in the Vs30 data (we could correct this by making an exception to the rule for the Salton Sea area).

We note how in the "RE then Vs30 GTL" idea, the main CVM-S GTL area in the LA basin is nicely preserved, but interestingly when you combine the RE + Vs30 GTL ideas some elements of the CVM-S GTL look like they have been almost recovered.