How to calculate geophone spice model?

Hi guys,

I need to simulate geophone such SM-6 4.5Hz.
I found:

Understanding the foundamentals of earthquake signal sensing networks (vol. 53 n° 3, december 2019)

I can find equivalent electrical model of geophone but:

1) on datasheet isn't reported coil spring constant (k), so from where do I get this value?

2) for same geophone I can find on the net several different electrical models, all with different RLC parameters (so behaviour). Where can I find hoe to calculate RLC parameters from gephone datasheet values? Thanks.