Geologists believe that the warning signs for a major earthquake may

Hi AjiteshArun CrackVerbalGMAT

(D) changes in the measured strain across a fault zone, and variations in

Does measured strain seem not like changes are in the measured strain only but not in unmeasured strain. What value word measured bring here? What about unmeasured?

If we think from this perspective then changes in measurements make more sense. It seems here whatever strains are measured , there would be changes in measurements. It seems there is definitely changes in all strains . Even we could not measure all, still it doesn't matter because whatever we measured , there are changes in strains.
(E) changes in measurements of the strain across a fault zone,

Please give your opinion on this decision making .

thanks! AjiteshArun CrackVerbalGMAT

Hi mSKR,

We should keep in mind that we're looking for "the warning signs for a major earthquake". We should not automatically assume that something that isn't measured can be a warning sign.

(D) Changes in the measured strain vs. (E) changes in measurements of the strain: D tells us that the strain is changing. E tells us that the measurements of the strain are changing. We could make a case for (E), but it is much better to say that changes in the strain are a warning sign than to say that changes in the measurements of the strain are a warning sign, because the measurements could change for other reasons as well.

In my opinion, (D) variations in vs. (E) variations among is the easier meaning call here.

Geologists believe that the warning signs for a major earthquake may include sudden fluctuations in local seismic activity, tilting and other deformations of the Earth's crust, changing the measured strain across a fault zone, and varying the electrical properties of underground rocks.


(A) changing the measured strain across a fault zone, and varying - ING modifier, this does not seem like a noun. ING modifier refers to the entire previous clause. If I'm reading this correctly it is like saying the signs include fluctuations in seismic activity, tilting and other deformations of the earth's crust thereby changing the measured strain and varying the electrical properties.

(B) changing measurements of the strain across a fault zone, and varying - now we have changing measurements of the strain which is in line with tilting and other deformations .... but the varying is still off.

(C) changing the strain as measured across a fault zone, and variations of - changing the strain as measured is awkward and doesnt convey the intended meaning. C's Out

(D) changes in the measured strain across a fault zone, and variations in - this looks good, no mistakes and easy to understand.

(E) changes in measurements of the strain across a fault zone, and variations among - its not the measurements that are changing but the measured strain that is.

IMO D

Hi GMAT Experts ,

I though that " changing the strain as measured across a faultzone" was a modifier to the "Tilting and other deformations" . Why is this approach wrong ?

Logically , we can then say that the three nouns are parallel - Sudden Fluctuations , Tilting & variations

Regards
RRJ12

We've already explained why "changing" doesn't really work as a noun (for more on that, see our explanation for (A) in this post). But let's assume that "changing the measured strain across a fault zone" is in fact a modifier that describes "tilting and other deformations..." and think about how that affects the meaning:

• In (D), the "changes in the measured strain across a fault zone" are a warning sign of a major earthquake, and that makes perfect sense. Strain is something that can be measured, and changes in that measurement might indicate that an earthquake is on the way.
• But in (C), it's (presumably) the tilting/deformations that change the strain as measured across a fault zone. That might make sense, but it leaves the reader wondering, "How are tilting and deformations changing the strain?"

That last point, admittedly, isn't very strong, but the "changing..." part in (C) raises other questions:

• "tilting and other deformations of the Earth's crust, changing the measured strain across a fault zone" -- if this whole thing is one single warning sign of a major earthquake, does that mean that the warning sign is limited to tilting/deformations that are changing the measured strain (and that tilting/deformations that are NOT changing the measured strain are NOT a warning sign)? Or do ALL tilting/deformations of the Earth's crust change the measured strain? It could go either way, making the intended meaning unclear.
• If we wanted to modify "tilting and other deformations of the Earth's crust," why not simply write, "tilting and other deformations of the Earth's crust that change the strain..."? That would make it perfectly clear that we have a modifier and not an additional element in the parallel list.
• As written, the "changing..." part in (C) certainly seems like it might be part of the list, making this sentence at best much more confusing than (D).

The bottom line is that (D) gives us a perfectly logical meaning without any room for interpretation. If we do some mental gymnastics, we can make (C) work, but at best the intended meaning is unclear.

Is (C) unequivocally WRONG from a grammatical standpoint? Maybe not. But (D) is definitely the better option.

I hope that helps!

The correct answer is (D): "changes in the measured strain across a fault zone, and variations in".

The sentence lists a series of warning signs for a major earthquake that geologists believe may occur. For this list to be clear and grammatically correct, it must maintain parallel structure, meaning that each item in the list should follow the same grammatical form.

(A) "changing the measured strain across a fault zone, and varying"

This option is incorrect because it breaks parallelism. The other elements in the list are nouns ("fluctuations", "tilting", "deformations"), but "changing" and "varying" are gerunds, which are verb forms.

(B) "changing measurements of the strain across a fault zone, and varying"

This option has the same problem as (A). The words "changing" and "varying" break parallelism with the rest of the list.

(C) "changing the strain as measured across a fault zone, and variations of"

This option also breaks parallelism. It mixes the gerund "changing" with the noun "variations".

(D) "changes in the measured strain across a fault zone, and variations in"

This is the correct answer. It maintains parallelism in the list by using the nouns "changes" and "variations".

(E) "changes in measurements of the strain across a fault zone, and variations among"

This option is incorrect because "variations among" is not as clear or precise as "variations in".

The main trap in this question is the maintenance of parallelism in a list. Many test-takers might not notice the shift from nouns to gerunds halfway through the list. It's crucial to ensure that all items in a list follow the same grammatical structure.