Geologists believe that the warning signs for a major earthquake may

Dear Friends,

Here is a detailed explanation to this question-

Meaning is crucial to solving this problem:
Understanding the intended meaning is key to solving this question; the intended meaning of the crucial part of this sentence is that sudden fluctuations in local seismic activity, tilting and other deformations of the Earth's crust, changes in the measured strain across a fault zone, and variations in the electrical properties of underground rocks are potential signs of a major earthquake.

Concepts tested here: Verb Forms + Parallelism + Meaning

• All elements in a list must be parallel.
• Please be careful when you come across the “verb+ing” construction; depending on the context, it may be a verb or a gerund (verb+ing acting as a noun).

A: The sentence formed by this answer choice fails to maintain parallelism among "sudden fluctuations", "tilting and other deformations of the Earth's crust", "changing...zone", and "varying...rocks"; “changing” is a verb here, while the other elements of this list are all nouns, including “tilting” which is a gerund; please remember, all elements in a list must be parallel.

B: The sentence formed by this answer choice fails to maintain parallelism among "sudden fluctuations", "tilting and other deformations of the Earth's crust", "changing measurements...zone", and "varying the...rocks"; “varying” is a verb here, while the other elements of this list are all nouns, including “tilting” which is a gerund; please remember, all elements in a list must be parallel. Further, Option B alters the meaning of the sentence through the phrase "changing measurements"; the construction of this phrase incorrectly implies that measurements of the strain across a fault zone that change are potential signs of a major earthquake; the intended meaning is that changes in the strain that is measured across a fault zone are potential signs of a major earthquake.

C: The sentence formed by this answer choice fails to maintain parallelism among "sudden fluctuations", "tilting and other deformations of the Earth's crust", "changing the strain...zone", and "variations of...rocks"; “varying” is a verb here, while the other elements of this list are all nouns, including “tilting” which is a gerund; please remember, all elements in a list must be parallel.

D: Correct. The sentence formed by this answer choice maintains parallelism among the nouns "sudden fluctuations", "tilting and other deformations of the Earth's crust", "changes in...zones", and "variations in...rocks". Further, Option D uses the phrases "changes in the measured strain across a fault zone" and "variations in... rocks", conveying the intended meaning - that changes in the strain that is measured across a fault zone and variations that take place in the different electrical properties of underground rocks are potential signs of a major earthquake.

E: This answer choice alters the meaning of the sentence through the phrase "changes in measurements"; the construction of this phrase incorrectly implies that changes that take place in measurements of the strain across a fault zone are potential signs of a major earthquake; the intended meaning is that changes in the strain across a fault zone that are measured are potential signs of a major earthquake. Put simply, Option E incorrectly implies that the measurements are changing; the intended meaning is that the strain is changing. Moreover, Option E further alters the meaning of the sentence through the phrase "variations among"; the construction of this phrase incorrectly implies that the differences among the different electrical properties of underground rocks are potential signs of a major earthquake; the intended meaning is that variations that take place in the different electrical properties of underground rocks are potential signs of a major earthquake.

Hence, D is the best answer choice.

Additional Note: Please understand that in this context, “tilting” is a gerund, a “verb+ing” construction that acts as a noun; it is one among a list of nouns, "sudden fluctuations", "tilting and other deformations of the Earth's crust", "changes in...zones", and "variations in...rocks", the potential signs of a major earthquake.

All the best!
Experts' Global Team

OA is D.

This SC i stesting for IIlism.
Geologists believe that the warning signs for a major earthquake may include A,B,C and D

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,
-changes in the measured strain across a faultzone, and
-variations in the electrical properties of underground rocks

Guys I would like to ask all of you that how can "sudden fluctuations" and "tilting" be parallel?
"tilting" is a simple gerund and "fluctuations" is an action noun, and according to MGMAT SC, simple gerunds and action nouns can't be parallel.
So the sentence goes like this:
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 variations in/of the electrical properties of underground rocks.

Regarding the preposition, MGMAT says that there is no compulsion on the prepositions to be the same.

Correct me if I am wrong.
Verbal experts noburu, metallicafan, Tommy please help.

D It is.

Geologists believe that the warning signs for a major earthquake may include j, k, l, and m. These j, k, l, m are the items in a list of a warning signs. Hence needs to be parallel.

The first two items are in the form of Adjectival Phrases 1) sudden fluctuations..... 2)tilting ...... of the earth's crust.
So to take care of parallelism remaining two items also need to be in the form of Adjectival phrase.

A) INCORRECT :- changing and varying are verbs, which can not parallel to phrases

B) INCORRECT :- varying is verb, which can not parallel to phrase. Also Change is in the strain and not in the measurements.

C) INCORRECT :- changing is verb, which can not parallel to phrase.

D) CORRECT :- This choice makes the remaining two signs parallel to previous signs. changes...... variations.....

E) INCORRECT :- changes are in the strain and not in the measurements.

Hope That Helps!

Yes, this is a tough one. The choice between D and E requires some really fine detail work. As several people have said, "among" is wrong because, in contrast to the meaning of A-D, that would be a comparison from one rock to another. It would be odd to expect the properties of all rocks to be the same in the first place. Additionally, changes in measurement shouldn't be a sign of an earthquake. We should be looking for changes in the thing we are measuring--strain. That makes this element parallel with the other signs--fluctuations in activity, tilting of the crust, etc.

As for developing a checklist, you don't want to do it! It certainly wouldn't have helped with D vs. E. If you were writing a computer program, sure, but you won't be able to apply that checklist efficiently on the test. Here's what I recommend:

1) Start by looking at the basic core of the sentence. Skip over modifiers to see the simple subject, verb, etc. Here, that would be "Geologists believe that the signs may include fluctuations, tilting and other deformations, changing, and varying." (Notice that I've left out adjectives and prepositional phrases.) The subject-verb relationships ("Geologists believe" and "signs may include") are fine, but the second half of the sentence has parallelism problems. That gets rid of A-C right away.

2) Once you've settled any issues with the core (sometimes there are none), you can start looking at meaning, modifiers, etc., but there's no time to go down a list. What's more helpful is to train yourself to spot these issues when they show up. See a sentence that starts with "Unlike"? Expect a comparison issue. See a modifier that moves around? Look at how it affects the meaning.

3) If you get stuck, guess and move on! There is nothing wrong with guessing between the final two on a question like this, even if you are aiming for 700+. Know when you are beat and save your time for problems you are able to resolve with confidence!

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 stain across a fault zone, and varying the electrical properties of underground rocks.

Issue: Parallelism | Meaning

Analysis:
1. The sentence can be broken down as following and the main issue at play here is parallelism. We need to make sure that all the warnings sign should be parallel is form. In the non-underlined part of the sentence, the warning sign are mentioned as noun. Hence, the warning sign in the underlined part should also be noun.

Geologists believe
│
that
│
warning signs... include
                  │
                  ├─ fluctuations...,
                  │
                  ├─ tilting and other deformations...,
                  │
                  ├─ changes...
                  │ 
                  and
                  └─ variations...

(A) changing the measured strain across a fault zone, and varying
- "changing" and "varying" used as a verb here; not parallel with nouns

(B) changing measurements of the strain across a fault zone, and varying
- "changing" and "varying" used as a verb here; not parallel with nouns

(C) changing the strain as measured across a fault zone, and variations of
- "changing" used as a verb here; not parallel with nouns

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

(E) changes in measurements of the strain across a fault zone, and variations among
- Illogical meaning; "Changes in measurement" is not the warning but rather "change in measured strain" is

Answer: (D)

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
(B) changing measurements of the strain across a fault zone, and varying
(C) changing the strain as measured across a fault zone, and variations of
(D) changes in the measured strain across a fault zone, and variations in
(E) changes in measurements of the strain across a fault zone, and variations among

Do "sudden fluctuations..." result in "changing.." and "varying.." -> honestly I don´t know. If it was so: A,B,C stand a chance. But then before the "and varying" there is a "," -> "and varying" -> this implies that this is part of a list of more than 2 items. Therefore A, B, C are out as "changing" and "varying" are not parallel to "fluctuations".. we need "changes" and "variations"
D is even better as "changes in" and "variations in" is parallel to "fluctuations in".

Did I do the analysis correctly? somehow I doubt

Hello Sahil01,

I would be glad to provide my two cents on the analysis that you ave presented.

The comma + verb-ing modifier modifies the preceding action. In this official question, the action that precedes comma + changing and varying is may include. This is for certain that just enumerating signs of something cannot lead to change or variation in anything. Hence, most definitely comma + changing and varying are NOT meant to be modifiers in this official sentence.

Hence, the sentence clearly tests parallelism. Personally, I do not rely on punctuation marks to accept or reject an answer choice.

Now that I am sure that the parallel list contains four elements that need to be parallel, I reject choice A, B, and C.

Between Choice D and E, D is definitely the correct one because the warning sign of a major earthquake will be change in the strain and not the change in the measurements of the strain.

Logic all the way and I get my correct answer.


Hope this helps.
Thanks.
Shraddha

Hi egmat

I had a similar query for coma+verb-ing modifiers since I selected OA as A.
I request you to help me with below understanding based on your reply:

Why the first modifier tilting is then used correctly?

The warning signs for a major earthquake include 4 things - a,b,c,& d. In this case - a,b,c,&d need to be parallel.

a - Sudden fluctuations in ..
b - tilting and other deformations of
c - (need to keep the consistency of writing) changes in the measured strain
d - variations in

As per my views, noun phrase (sudden fluctuations in ..) in (a) seems parallel
with verb-ing modifier tilting + of..(b) and nouns phrases changes
in (c) and variations in (d): which is correct from grammar point of view.

Also variations in rocks and variations among rocks too convey different meaning?

WR,
Arpit

Hello adkikani /Arpit,

Thank you for the query.

The word tilting is NOT a modifier. It is the "ing" noun form and hence is parallel to other noun phrases in the list.

Please note that tilting is NOT a gerund - an "ing" noun that denotes action. It is so because in the original sentence, tilting is followed by the preposition of. One of the warning signs includes tilting of the Earth's crust and other deformations of the Earth's crust. Gerunds are never followed by a preposition.

So the noun form tilting is perfectly parallel to the other noun phrases in the list.

And yes, variations in and variations among are not same. They do denote different meanings. quite literally.


Hope this helps.
Thanks.
Shraddha

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.

Understanding the intended meaning : After reading the sentence its clear that the sentence is talking about the list of warning signs for a major earthquake as believed by the geologists.

At first look, though, I even had a thought whether "tilting" is acting like a VERB-ing modifier and the remaining two -ing forms (changing and varying) are parallel to the tilting. So, I quickly checked the same. The VERB-ing modifiers should make sense with the SUBJECT and VERB of the preceding clause. Here, preceding clause is an essential modifier.

Preceding Clause -- the warning signs for a major earthquake (SUBJECT) may include (VERB) sudden fluctuations in local seismic activity, tilting...
This is for certain that just enumerating signs of something cannot lead to tilting in anything. Though Tilting can be included as a part of this list. Hence, most definitely comma + tilting is NOT meant to be a modifier in this sentence. Then what is this "tilting"?? It is acting as an ACTION NOUN or more technically, Complex Gerund. SO, from here we got that the remaining portions of the underlined part should also be nouns for the list to be parallel. So, need to quickly go through the choices to look for parallelism.

(A) changing the measured strain across a fault zone, and varying
varying is NOT the noun form. Therefore, it breaks parallelism. ALso, usage of "changes" is better than "changing". When a noun form is available, we prefer not to use the "-ING" form of verbs. Incorrect.

(B) changing measurements of the strain across a fault zone, and varying
varying is NOT the noun form. Therefore, it breaks parallelism. Also, there is a meaning issue with this choice. Changing measurements of the strain is not correct. Changing the measured strain is the intended meaning. ALso, usage of "changes" is better than "changing". When a noun form is available, we prefer not to use the "-ING" form of verbs. Incorrect.

(C) changing the strain as measured across a fault zone, and variations of
changes is better than changing. Also, when a noun form is available, we prefer not to use the "-ING" form of verbs. Variations of is non idiomatic. Therefore, incorrect.

(D) changes in the measured strain across a fault zone, and variations in
CHANGES is a proper noun form, compared to CHANGING. Also, the intended meaning -- changes in the strain is clear. Usage of "Variations in" is idiomatic. Correct.

(E) changes in measurements of the strain across a fault zone, and variations among
Similar issue in meaning as choice B. Also, variations among is NOT idiomatic. Incorrect.

Hello aceGMAT21,

Your meaning-based approach to solve this official question is very thorough. Great job there. Keep it up.


It is true that one mat think that comma + tilting might have been used a comma + verb-ing modifier in this official sentence. However, if just pay attention to the structure of this part of the sentence, we will know that tilting is a noun.

The word tilting in the non-underlined portion is followed and. Presence of and suggests that there is a list in here. What follows and, i.e., the last entity in the list is other deformations, a noun entity. Hence, titling has to be a noun to form a parallel list with other deformations.


Hope this helps.
Thanks.
Shraddha

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
(B) changing measurements of the strain across a fault zone, and varying
(C) changing the strain as measured across a fault zone, and variations of
(D) changes in the measured strain across a fault zone, and variations in
(E) changes in measurements of the strain across a fault zone, and variations among

Notwithstanding what has been given in the non-underlined part, structurally speaking, the ", changing" in A, B and C absurdly imply that the subject of the previous clause namely 'the signs' is the doer of the said actions. Therefore neck them out in one go.
Then it does not take much to dump for the unidiomatic 'variations among'. In addition, choice E changes the intent to say that the measurements have changed rather than the original measured strains.
A nice meaning based question although structure and parallelism play a major role in diagnosing incorrect choices.

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>>
changing , varying - verb form which are not parallel to the noun list

(B) <<changing>>measurements of the strain across a fault zone, $and$ <<varying>>
changing - verb form which is not parallel to the noun list

(C) <<changing>> the strain as measured across a fault zone, $and$ [variations] of
changing , varying - verb form which are not parallel to the noun list

(D) [changes] in the measured strain across a fault zone, [and] [variations] in
changes , variations - noun form which are parallel to the noun list

(E) [changes in <measurements>] of the strain across a fault zone, [and] [variations <among> ]
+ the meaning is illogical
1)changes in the measurements and not the strains
2) variations among the electrical properties and not in the electrical properties itself


<< >> - verb phrases
[ ] - noun phrases
<> - errors
$ $ - keywords

in this sentence we are looking for a list of noun phrases, [x],[y], $and$ [z] and the list is indicated by the key words $warning signs$ $may include$

May include
X= fluctuations in another list
Y=changes
Z=variations
May include X, Y, and Z (a list)

That other list is not part of the first element.

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

Is "tilting" noun in the list? If yes, isn't it a modifier?