Your question in its present form is unanswerable. Tensile strength is not the limiting factor of how space elevators are designed. Space elevators are designed to have an
arbitrary constant amount of tension. This is accomplished by varying the thickness of the cable as you move up to either L1 or a GEO orbit for earth.
Imagine it this way, when you start at the bottom where the cable touches the ground there is no force so the cable can be as small as you want. Go up one mile and now the cable has to be at least as thick as it was at the bottom plus additional thickness to carry all of the weight of the cable below it. This sort of design is called a constant tension space elevator because the thickness is varied to keep the tension constant. The first designs of space elevators used constant cross-sections, but that design has long since been abandoned because it is mass-inefficient to the point that no material could work (even carbon nano-tubes on earth).
So, I think what you really want is a comparison of taper ratios on earth versus a moon L1 elevator. The taper should start at a minimum and reach its maximum at either GEO or L1 and then taper down to a counterweight. Derivation time.
For earth, where T is the tension in the cable, $\rho$ is the density of the cable, $\mu_e$ is the standard gravitational parameter of earth and $\omega$ is the angular velocity of earth's rotational period. An intuitive explanation of the terms: The terms on the left side is the tension holding the cable up at some point dr, the terms on the right are first gravity dragging you down and then centripetal acceleration slinging you up.
$T \space dA = \rho A(\mu_e/r^2 - \omega^2 r ) \space dr $
$ dA/A = (\rho /T )(\mu_e/r^2 - \omega^2 r ) \space dr $
Re-arranging and integrating from the surface $R_s$ to GEO $R_g$.
$ln(A_g/A_s) = (\rho /T )(\mu_e(1/R_s -1/R_g) + \omega^2/2(R_g^2 -R_s^2)) $
$TaperRatio =A_g/A_s =exp[ (\rho /T )(\mu_e(1/R_s -1/R_g) + \omega^2/2(R_g^2 -R_s^2))] $
I am going to use kevlar as an example because it has one of the best strength to weight ratios of any material.
$\rho $ = 1400 Kg/m^3
T = Max tensile strength = 3.6 GPa = 3.6 *10^9 Pa
*note if doing the calculation yourself, $\rho/T$ needs to be in s^2/km^2 units for everything to cancel properly.
I am going to incorporate a safety factor of 1.1, which makes the max T = 3.27 GPa.
Assuming $R_s$ = 6371 Km, $R_g$ = 42164 Km, $\mu_e$ = 398600 Km^3/s^2, $\omega$ = 7.272e-5 rad/s, and $\rho/T$ = .3889 s^2/km^2, The taper ratio for a Kevlar based earth elevator would be 5.2577e+10. This large taper ratio is why the elevator would be impractical on earth.
Now for the derivation of the taper ratio on a lunar L1 elevator. This answer does not apply to an L2 elevator. The basic force balance equation is the same except now there is a term for the effect of earth's gravity. The earth also pulls up on the elevator. The constant c is just the radius of the orbit between the earth and the moon and $\omega$ is now the angular velocity of the moon instead of the earth. Since the the moons rotational period and orbital period are very similar, the moon is tidally locked. I assume a perfect tidal lock, if this was a real design you would have to allow the tether to move around on the surface of the moon a little bit.
$T \space dA = \rho A(\mu_m/r^2 -\mu_e/(c-r)^2 - \omega^2 r ) \space dr $
Re-arranging and integrating from the surface of the moon $L_s$ to Lagrange point 1 $L_1$.
$A_1/A_s =exp[ (\rho /T )(\mu_m(1/L_s -1/L_1) + \omega_m^2/2(L_s^2 -L_1^2)) + \mu_e(1/(c-L_s) -1/(c-L_1))] $
Here is the simplified equation for the L1 elevator if you want to try it yourself for various materials.
$TR = exp((\rho\space 2.5289)/T)$
Plugging in using the same safety factor and Kevlar, you get a taper ratio of 2.95 for an L1 elevator where $L_s$ = 1738 Km, $L_1$ = 63008 Km, C = 384400 Km, $\mu_m$ = 4900 Km^3/s^2, and $\omega_m$ = 2.6617e-06 rad/s.
To sum it all, taper ratios are how you compare different elevators not tensile strength requirements. For earth with Kevlar, the TR is 5.2577e+10 and for a moon-L1 elevator it is 2.95. This is what I believe @LaurenPechtel's answer is talking about for blowing up exponentials.
Once you have found your taper ratio, you can then begin looking at how much mass you want to lift. Lets say you want your elevator to be able to lift 100 thousand kilos, you just do a force balance at the bottom and that sets your starting area.
$A_s T = mg => A_s = mg/T $
On the moon that means you need an initial cross section of .45 cm^2 and a max cross section at L1 of 1.35 cm^2 to lift 100,000 Kg. On Earth, it would be 2.72 cm^2 starting cross section and 14.3125 Km^2 max cross section at GEO.
Bringing the counterweight closer to L1 from the Earth side will not change the tension requirements at all. It just changes where you decide to stop tapering down. Read this paper to understand why.
Last thought, the image you show for an L1 elevator can be somewhat confusing. An L1 elevator does not need a section to the pole for engineering reasons. Everyone who has looked into L1 elevator designs, generally has thought it would be nice to go straight to the poles. It is possible to attach a secondary string from the main elevator to the poles, but this is done for mission reasons.