In 1971 researchers hoping to predict earthquakes in the short term by identifying precursory phenomena (those that occur a few days before large quakes but not otherwise) turned their attention to changes in seismic waves that had been detected prior to earthquakes. An explanation for such changes was offered by “dilatancy theory,” based on a well-known phenomenon observed in rocks in the laboratory: as stress builds, microfractures in rock close, decreasing the rock’s volume. But as stress continues to increase, the rock begins to crack and expand in volume, allowing groundwater to seep in, weakening the rock. According to this theory, such effects could lead to several precursory phenomena in the field, including a change in the velocity of seismic waves, and an increase in small, nearby tremors. Researchers initially reported success in identifying these possible precursors, but subsequent analyses of their data proved disheartening. Seismic waves with unusual velocities were recorded before some earthquakes, but while the historical record confirms that most large earthquakes are preceded by minor tremors, these foreshocks indicate nothing about the magnitude of an impending quake and are indistinguishable from other minor tremors that occur without large earthquakes. In the 1980s, some researchers turned their efforts from short-term to long-term prediction. Noting that earthquakes tend to occur repeatedly in certain regions, Lindh and Baker attempted to identify patterns of recurrence, or earthquake cycles, on which to base predictions. In a study of earthquake-prone sites along the San Andreas Fault, they determined that quakes occurred at intervals of approximately 22 years near one site and concluded that there was a 95 percent probability of an earthquake in that area by 1992. The earthquake did not occur within the time frame predicted, however. Evidence against the kind of regular earthquake cycles that Lindh and Baker tried to establish has come from a relatively new field, paleoseismology. Paleoseismologists have unearthed and dated geological features such as fault scarps that were caused by earthquakes thousands of years ago. They have determined that the average interval between ten earthquakes that took place at one site along the San Andreas Fault in the past two millennia was 132 years, but individual intervals ranged greatly, from 44 to 332 years. 1 (Book Question: 11) 1. The passage is primarily concerned with A. explaining why one method of earthquake prediction has proven more practicable than an alternative method B. suggesting that accurate earthquake forecasting must combine elements of long-term and short-term prediction C. challenging the usefulness of dilatancy theory for explaining the occurrence of precursory phenomena D. discussing the deficiency of two methods by which researchers have attempted to predict the occurrence of earthquakes E. describing the development of methods for establishing patterns in the occurrence of past earthquakes 2 (Book Question: 12) 2. According to the passage, laboratory evidence concerning the effects of stress on rocks might help account for A. differences in magnitude among earthquakes B. certain phenomena that occur prior to earthquakes C. variations in the intervals between earthquakes in a particular area D. differences in the frequency with which earthquakes occur in various areas E. the unreliability of short-term earthquake predictions 3 (Book Question: 13) 3. It can be inferred from the passage that one problem with using precursory phenomena to predict earthquakes is that minor tremors A. typically occur some distance from the sites of the large earthquakes that follow them B. are directly linked to the mechanisms that cause earthquakes C. are difficult to distinguish from major tremors D. have proven difficult to measure accurately E. are not always followed by large earthquakes 4 (Book Question: 14) 4. According to the passage, some researchers based their research about long-term earthquake prediction on which of the following facts? A. The historical record confirms that most earthquakes have been preceded by minor tremors. B. The average interval between earthquakes in one region of the San Andreas Fault is 132 years. C. Some regions tend to be the site of numerous earthquakes over the course of many years. D. Changes in the volume of rock can occur as a result of building stress and can lead to the weakening of rock. E. Paleoseismologists have been able to unearth and date geological features caused by past earthquakes. 5 (Book Question: 15) 5. The passage suggests which of the following about the paleoseismologists’ findings described in lines 42–50? A. They suggest that the frequency with which earthquakes occurred at a particular site decreased significantly over the past two millennia. B. They suggest that paleoseismologists may someday be able to make reasonably accurate long-term earthquake predictions. C. They suggest that researchers may someday be able to determine which past occurrences of minor tremors were actually followed by large earthquakes. D. They suggest that the recurrence of earthquakes in earthquake-prone sites is too irregular to serve as a basis for earthquake prediction. E. They indicate that researchers attempting to develop long-term methods of earthquake prediction have overlooked important evidence concerning the causes of earthquakes. 6 (Book Question: 16) 6. The author implies which of the following about the ability of the researchers mentioned in line 18 to predict earthquakes? A. They can identify when an earthquake is likely to occur but not how large it will be. B. They can identify the regions where earthquakes are likely to occur but not when they will occur. C. They are unable to determine either the time or the place that earthquakes are likely to occur. D. They are likely to be more accurate at short-term earthquake prediction than at long-term earthquake prediction. E. They can determine the regions where earthquakes have occurred in the past but not the regions where they are likely to occur in the future.

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In the last question, I'm unable to understand why C is correct and A is wrong.

First of all, this is an inference question, right? Because OG has put it under the 'supporting idea' category and the explanation also reads "The question asks for information explicitly stated..."

Quote:

Also, if someone can explain the answer choices A & C as provided by the OG. Thanks!

Hey hannahkagalwala,

It is indeed an inference question, albeit detail oriented, since the question stem clearly asks us to look for an implication of the information given in a particular section of the passage.

Now let's look at choice A:

A. They (1) can identify when an earthquake is likely to occur but (2) not how large it will be.

So, choice A talks about the two things:

1. can identify when an earthquake is likely to occur : Passage states, and I quote, " are indistinguishable from other minor tremors that occur
without large earthquakes. Basically, this information tells us that yes tremors do happen but the kind of tremors that are followed by earthquakes are not different from the kind of tremors that are NOT followed by earthquakes. Accordingly, if such tremors happen without a resulting earthquake, then the researchers cannot really tell us whether an earthquake is due.

2. not how large it will be. This can be directly understood from this section of the passage "nothing[/b] about the magnitude of an impending quake.

Therefore, since one part can be inferred and one cannot be, this choice is incorrect.

Now, let's take a look at Choice C.

C. They are unable to determine either the time or the place that earthquakes are likely to occur.

When I read this choice initially, the "place" aspect did throw me off a little-bit, but after reading the information one more time and looking at the other answer choices, I went along with Choice C. So, here are my cents on it:

Quote:

Secondly, the passage states the foreshocks are indistinguishable from other minor tremors that occur without large earthquakes. At a stretch, it could mean that they are unsure of the time.

1. unable to determine either the time - This portion, as you agree to an extent, is correct for the reasons explained above (refer to point no. 1 under the explanation for choice A for more detail).

Quote:

But how can they be unsure of the place? The tremors are 'nearby' as stated in the passage.

2. place that earthquakes are likely to occur - Alright, so let's look at how the whole information about tremors observed "nearby" places is given to us. We are basically told that after stress increases beyond a particular point in the rocks, something happens, leading to tremors and other things in the areas nearby to these rocks. Right? But then we are also told that just because these tremors occur, we cannot predict that an earthquake will follow. So, when you combine these two pieces of information, it means that say at place xyz, the researchers observe tremors, but they can't really say that at this place, there will be an earthquake. This is why the whole "place" angle makes sense - even though one is not very comfortable with it in the beginning.

Hope the above explanation helps.

Cheers!

Probably the answer still remains C, but 2 things:

First, Attention!! please what you imply is wrong
they say without LARGE earthquakes, not without earthquakes... it's hugely different.
Second, strongly tied with the first point, this is the most contestable official question-answer in RC that I've ever seen.
I'm still open to serious facts against A and not things that seem to support C

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Hi experts GMATNinjaTwo GMATNinja

Can someone explain, why D is correct in question 5?

Thanks!

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Question 5

Adambhau

Hi experts GMATNinjaTwo GMATNinja

Can someone explain, why D is correct in question 5?

Thanks!

Question 5 asks about some findings described in lines 42-50. Before diving into those exact lines, however, it's important to understand the broader context of that piece of the passage. Why is the author talking about the findings in the first place?

In the third paragraph, the author introduces the idea of "earthquake cycles." If earthquakes happened at regular intervals, that would be incredibly helpful in predicting when the next earthquake would occur.

But then, in the fourth paragraph, the author introduces evidence against the existence of regular earthquake cycles. This evidence comes from paleoseismologists, and their findings are described in lines 42-50:

"Paleoseismologists have unearthed and dated geological features such as fault scarps that were caused by earthquakes thousands of years ago. They have determined that the average interval between ten earthquakes that took place at one site along the San Andreas Fault in the past two millennia was 132 years, but individual intervals ranged greatly, from 44 to 332 years.

Overall, this evidence shows that earthquake cycles aren't particularly useful in predicting exactly when the next earthquake will come around -- if someone told you that an earthquake will strike sometime within the next 44 to 332 years, you probably wouldn't find that to be a super helpful prediction.

This is captured perfectly in (D): the paleoseismologists' work suggests that "the recurrence of earthquakes in earthquake-prone sites is too irregular to serve as a basis for earthquake prediction."

(D) is the correct answer to question 5.

I hope that helps!

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Hi stonecold, good question!

Quote:

I have a query regarding the last question in this series.
We are asked about the ability of the researchers in the line 18.
The passage clearly indicates and even mentions -> They were able to predict the timing but not the magnitude." indistinguishable from other minor tremors that occur"

I am still convinced that the OA should be A.

What am i missing.?

P.S-> I have seen the other replies.
without large earthquakes.

Imagine that the researchers recorded 100 large earthquakes of various magnitudes during their study and that nearly all of those large earthquakes were preceded by minor tremors. This might lead us to expect any minor tremor to be followed by a large earthquake, even though we might not know exactly how large that "large" earthquake will be. Thus, choice A is tempting.

Now consider the final fact given in line 23: "these foreshocks... are indistinguishable from other minor tremors that occur without large earthquakes." If instead the passage stated, "these foreshocks are indistinguishable from other minor tremors that occur before small earthquakes", THEN choice A would be defensible... this would imply that after a minor tremor we can expect an earthquake, though we have no idea how small or large it will be. But the passage states that the tremors are "indistinguishable from other minor tremors that occur without large earthquakes." Therefore, the passage implies that a minor tremor could be followed by a large earthquake, a small earthquake, or no earthquake at all; for example, the researchers may have recorded HUNDREDS of minor tremors that were NOT followed by an earthquake.

This explanation is supported by the first sentence starting in line 17: "Researchers initially reported success in identifying these possible precursors, but subsequent analyses of their data proved disheartening." In other words, the researchers were initially successful in identifying earthquake precursors; subsequent analyses proved disheartening, implying that the researchers were not successful in identifying precursors that would predict earthquakes.

I hope that helps!

So where my confusions lies is that the passage explicitly states "without large earthquakes." Now the question isn't asking about large earthquakes but earthquakes in general, so as such I interpreted the passage to mean that the tremors aren't correlated with magnitude but are correlated with an earthquake, large or small, and as a result I thought A was the correct answer. If the question choice had mentioned "LARGE" earthquakes specifically I likely would have went with C instead of A.

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GMATNinjaTwo

Hi stonecold, good question!

Quote:

The problem is that “without large earthquakes” does not necessarily imply that a small earthquake occurs. It’s equally likely that no earthquake occurs. For (A) to be correct, we’d have to assume that “without large earthquakes” means that a small earthquake did occur. We can’t do that, so we eliminate (A).

I hope that helps!

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@GMATNinjaTwo...can you help me by explaining why option E is wrong in Q6. I think the scientists are able to determine where the earth quakes have occurred in the past?

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Question 6

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@GMATNinjaTwo...can you help me by explaining why option E is wrong in Q6. I think the scientists are able to determine where the earth quakes have occurred in the past?

Question 6 asks us to choose the answer choice that is implied by the author of the passage. So, does the author imply that the researchers in line 18 can tell where earthquakes occurred in the past?

To answer detailed questions like this, go back to that specific portion of the passage to see what the author has said:

Quote:

Researchers initially reported success in identifying these possible precursors, but subsequent analyses of their data proved disheartening. Seismic waves with unusual velocities were recorded before some earthquakes, but while the historical record confirms that most large earthquakes are preceded by minor tremors, these foreshocks indicate nothing about the magnitude of an impending quake and are indistinguishable from other minor tremors that occur without large earthquakes.

Here, there's no discussion about what these researchers knew concerning past earthquakes. The researchers tried to identify precursors to future earthquakes, and the author focuses on how analysis of the researchers' data is "disheartening." He/she then goes on to describe why the data isn't that helpful in predicting earthquakes.

The passage really doesn't discuss at all what these particular researchers knew about the regions where earthquakes happened in the past. Later in the passage, the author implies that some other researchers knew this information, but those are not the researchers that question 6 asks about.

It may seem like a reasonable assumption to say that the researchers knew something about past earthquakes, but that is simply never implied by the author of the passage. So you can eliminate (E) for question 6.

I hope that helps!

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KarishmaB why not choice B in question 6?

Also later in the passage when it talks about 'some researchers' are the researchers being referred to the same as earlier or these are different? And how do you identify that

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6. The author implies which of the following about the ability of the researchers mentioned in line 18 to predict earthquakes?

A. They can identify when an earthquake is likely to occur but not how large it will be.
B. They can identify the regions where earthquakes are likely to occur but not when they will occur.
C. They are unable to determine either the time or the place that earthquakes are likely to occur.
D. They are likely to be more accurate at short-term earthquake prediction than at long-term earthquake prediction.
E. They can determine the regions where earthquakes have occurred in the past but not the regions where they are likely to occur in the future.

Researchers initially reported success in identifying these possible precursors, but subsequent analyses of their data proved disheartening. Seismic waves with unusual velocities were recorded before some earthquakes, but while the historical record confirms that most large earthquakes are preceded by minor tremors, these foreshocks indicate nothing about the magnitude of an impending quake and are indistinguishable from other minor tremors that occur without large earthquakes.

This is all that is given to us about "researchers" mentioned in line 18. What can we say about these researchers? That their methods failed to tell us anything about precursors to earthquakes. The passage doesn't tell us that they could tell the regions where earthquakes would occur. Their methods had failed to give any reliable insight.

Next passage starts with "In the 1980s, some researchers turned their efforts from short-term to long-term..." This is a good 10-15 years after 1971 and we are talking about "some researchers". It is not implied that they are the same researchers (using 'those researchers' etc). Also, it starts from a new paragraph so it's the next thought. Hence, we should ignore anything and everything given in the next paragraph.

So option (C) is correct.

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Hi experts,

I read through the responses on the fourm thoroughly, and unfortunately, my doubts have not been resolved. I would be so appreciative for any clarification on the following...

For "the passage is primarily concerned with", to clarify, Choice C is incorrect because it only mentions challenging the usefulness of dilatancy theory for explaining the occurrence??of precursory phenomena and NOT also challenging Lindh??and Baker's regular earthquake cycle theory whereas Choice D goes against both???

For "according to the passage, laboratory evidence concerning...", Choice C is referring to Lindh and Baker's method, correct? Choice D is incorrect because although I believe that this is referring to Lindh and Baker's method... Lindh and Baker's method only even looked at the San Andreas Fault? Choice E is incorrect because it is only LATER (the next paragraph) that the laboratory evidence is discovered as being unreliable, correct?

For "according to the passage, some researchers based their research..." I see why Choice C is the best answer choice. However, Choice D seems to be a trap answer no? Technically, both Lindh and Baker and the Paleoseismologists discuss long-term earthquakes/that they take place over many years. Do you see what I mean? Choice C does not seem to be saying that this is a matter of regular vs. irregular... just that they occur? Any further clarity on differentiating between these two answer choices would be greatly appreciated.

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For "the passage is primarily concerned with", to clarify, Choice C is incorrect because it only mentions challenging the usefulness of dilatancy theory for explaining the occurrence??of precursory phenomena and NOT also challenging Lindh??and Baker's regular earthquake cycle theory whereas Choice D goes against both???

Basically, yes. The passage does exactly the same thing (a setup/background and a description of the researchers' optimistic views, but then a description of how the theory ultimately failed) twice—first for dilatancy theory and then for Baker and Lindh's theory.

Choice C implies that the part about dilatancy theory is part of the main idea, but that the part about Baker's and Lindh's theory is not. That's absolutely impossible, because the two parts are functionally identical—if one of them is part of the main theme, then so is the other one.

Choice C is also totally wrong for a second reason: it says that the passage challenges (= goes against) the usefulness of dilatancy theory "for explaining the occurrence of precursory phenomena".
That's not true. According to the passage, dilatancy theory SUCCESSFULLY explained/elaborated on the occurrence of (at least some) "precursory phenomena" (= events that occur in the build-up to a big earthquake). The failure point of dilatancy theory was that it couldn't PREDICT EARTHQUAKES.

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For "according to the passage, laboratory evidence concerning...", Choice C is referring to Lindh and Baker's method, correct? Choice D is incorrect because although I believe that this is referring to Lindh and Baker's method... Lindh and Baker's method only even looked at the San Andreas Fault? Choice E is incorrect because it is only LATER (the next paragraph) that the laboratory evidence is discovered as being unreliable, correct?

First things first: Here, all of your questions are about the wrong answers; you aren't asking anything about the correct answer or the path of reasoning that leads to it.
It's possible, of course, that you're not asking about these things because everything about the correct answer is clear to you now. If so, good.
—BUT— The other possibility is that you're just not thinking about the correct answer because you're approaching this problem primarily with process-of-elimination. If that's the case, you're making a mistake. On detail-based questions, you should FIRST see whether you can find what you need in the passage and then AFFIRMATIVELY identify the CORRECT answer. Process-of-elimination is something you should do only if you don't succeed in just going to the passage, finding the relevant information, figuring out what the correct answer SHOULD say/do, and then just going and finding it.

Do you understand how the CORRECT answer works? (Short version: The passage says that the stress stuff may explain "precursory phenomena". To answer the question, you just have to know what "precursory phenomena" are—a definition that you can find at the very beginning of the passage OR that you can actually just figure out from the normal, literal meanings of "precursory" and "phenomena").

Quote:

Choice C is referring to Lindh and Baker's method, correct?

No. Lindh and Baker thought that earthquakes would occur in these areas at REGULAR intervals—i.e., that there would be essentially NO "variation in intervals".

"Variation in intervals" means that the numbers of years between successive earthquakes is IRREGULAR. That turned out to be true—which was precisely the thing that DEFEATED the Baker and Lindh theory.
This "variation" is the thing in the very last paragraph; it was established by "a relatively new field, paleoseismology".

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Choice D is incorrect because although I believe that this is referring to Lindh and Baker's method... Lindh and Baker's method only even looked at the San Andreas Fault?

That's not the problem. At the start of the discussion of Baker and Lindh, the passage notes that they were aware of repeated earthquakes in "certain regions" (plural)—which accords with "various areas".
(The passage describes a study on just the San Andreas, but, that's expected—the researchers and their equipment can only be in one place at a time. Studying one instance of something in order to figure out things that can be generalized to LOTS of instances is exactly how scientific research works—across basically all fields of science. As an analogy, an oncologist studying the development of cancer can only study it in one patient at a time, but observations on one patient with a certain kind of cancer are clearly relevant to the thousands of other patients who have the same kind of cancer.)

In any case, you're overthinking this. Stress patterns in rocks are only mentioned in the first paragraph, so, they are only relevant to the stuff in that paragraph. Baker and Lindh are not mentioned until the third paragraph, so they have nothing at all to do with stress patterns in rocks.
Therefore, D is just irrelevant. If you find yourself stuck doing process-of-elimination, you should at least be able to eliminate D quickly.

Quote:

Choice E is incorrect because it is only LATER (the next paragraph) that the laboratory evidence is discovered as being unreliable, correct?

Evidence can't be "unreliable". That doesn't make sense—"Evidence" is FACTUAL data. Data are data are data. Facts are facts. Once something has been established as a fact, it can't be "unreliable".

If you formulate a THEORY that you think will allow you to DO something with that factual evidence—such as to predict earthquakes, here—then that methodology might turn out to be "unreliable" if it doesn't let you do what you're trying to do with it.

In this instance, there are two steps to the prediction process: /1/ Rock stress patterns are used to predict "precursory phenomena", and then /2/ "precursory phenomena" are used to predict earthquakes.

As described in the second paragraph, the problem was step 2. The rock stress data is only related to step 1, so, no, it doesn't help explain the problem.

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For "according to the passage, some researchers based their research..." I see why Choice C is the best answer choice. However, Choice D seems to be a trap answer no?

I don't know what you mean by "trap answer", but the GMAT does not contain ANY answer choices that are misleading or that are worded in 'tricky' ways (i.e., that require you to interpret words in some obscure way that normal people—reading carefully and literally, but otherwise just normally—would not come up with).

If "trap answer" means "it's written to try to trick/deceive you", then, there are a total of zero 'trap answers' in GMAC's entire output of problems.

If "trap answer" just means "contains something that might make somebody choose it", then basically every wrong answer choice on every question would be one! (The alternative would be to write wrong answer choices that are so stupid that nobody would ever pick them, which would make the entire test rather silly as an enterprise.)

About choice D—That choice deals with stress patterns in rocks. That's in the first paragraph, which is only about SHORT-term prediction, so D is irrelevant.

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Technically, both Lindh and Baker and the Paleoseismologists discuss long-term earthquakes/that they take place over many years. Do you see what I mean?

The adjective "long-term" is only used here for earthquake PREDICTION.

Baker and Lindh were, indeed, trying to find a way to make long-term earthquake predictions.

The paleoseismologists are not concerned with prediction at all (..not as described here, at least). Their deal is looking at geological evidence to figure out when PAST earthquakes happened.

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Choice C does not seem to be saying that this is a matter of regular vs. irregular... just that they occur?

That's exactly what it says. The point is that Baker and Lindh were looking for regular periodic occurrences (because those would let them predict future quakes, at the same intervals), but they didn't know whether, or where, these were actually regular... so they had to do research!

This is what the words literally say:
Noting that earthquakes tend to occur repeatedly in certain regions, Lindh and Baker attempted to identify patterns of recurrence

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08 Oct 2022, 07:19

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Hi RonTargetTestPrep KarishmaB GMATNinjaTwo ReedArnoldMPREP GMATNinja : quick question on 6, answer (E) specifically.

I dont see why the first half (in green) is wrong.

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E. They can determine the regions where earthquakes have occurred in the past but not the regions where they are likely to occur in the future.

We should be able to "infer" the green font half in (E) becuase of the following lines in the passage

Line 21 : ...............but while historical record confirms that most large earthquakes are preceded by minor tremors....

If Line 21 is true - that MUST MEAN that researchers ** can determine ** the regions where earthquakes have occured in the past.

Why ?

Well, because there are historical records of past earthquakes.

So the Researchers **CAN** Determine the regions where earthquakes have occured in the past.

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10 Oct 2022, 20:58

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jabhatta2

Hi RonTargetTestPrep KarishmaB GMATNinjaTwo ReedArnoldMPREP GMATNinja : quick question on 6, answer (E) specifically.

I dont see why the first half (in green) is wrong.

Quote:

E. They can determine the regions where earthquakes have occurred in the past but not the regions where they are likely to occur in the future.

We should be able to "infer" the green font half in (E) becuase of the following lines in the passage

Line 21 : ...............but while historical record confirms that most large earthquakes are preceded by minor tremors....

We are talking about the researchers in line 18 and their ability to predict earthquakes.

6. The author implies which of the following about the ability of the researchers mentioned in line 18 to predict earthquakes?

The passage does not mention or imply that these researchers had the ability to "determine the regions where earthquakes have occurred in the past."

The passage says that 'historical record confirms that most large earthquakes are preceded by ...' so we can say that this implies that we do know about past earthquakes but who determined the regions where they took place etc is not given to us. Who determined the regions and other info about these earthquakes and made records is not known. There is no reason to assume that it was determined by these researchers.

Besides, we are talking about the ability of these researchers in the case of predictions (earthquakes in future) so a discussion about the past is irrelevant.

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26 Jun 2023, 09:22

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1. The passage is primarily concerned with

A. explaining why one method of earthquake prediction has proven more practicable than an alternative method
Both the methods ie, dilatancy theory (analyses of foreshocks) and earthquake cycles suffer from glaring deficiencies. No evaluations amongst the two methods has been presented in the passage

B. suggesting that accurate earthquake forecasting must combine elements of long-term and short-term prediction
Such a suggestion by author is not mentioned in the passage

C. challenging the usefulness of dilatancy theory for explaining the occurrence of precursory phenomena
dilatancy theory's usefulness has been challenged in only the 2nd paragraph. Too limited in scope

D. discussing the deficiency of two methods by which researchers have attempted to predict the occurrence of earthquakes
The main point of the passage is : 'Both the methods ie, dilatancy theory (analyses of foreshocks) and earthquake cycles suffer from glaring deficiencies'.

E. describing the development of methods for establishing patterns in the occurrence of past earthquakes
no description of timeline in the development of methods can be found in the passage

The correct option is (D)

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Updated on: 28 Jun 2023, 06:22

Originally posted by rn1112 on 26 Jun 2023, 09:58.
Last edited by rn1112 on 28 Jun 2023, 06:22, edited 1 time in total.

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2. According to the passage, laboratory evidence concerning the effects of stress on rocks might help account for

A. differences in magnitude among earthquakes
No such claims regarding magnitude linked to the laboratory evidence in the passage

B. certain phenomena that occur prior to earthquakes
the passage highlights that the effects of stress lead to precursory phenomena in the form of minor tremors

C. variations in the intervals between earthquakes in a particular area
these pertain to earthquake cycles method of predicting earhquakes !!

D. differences in the frequency with which earthquakes occur in various areas
Similar to (C) above. such an argument has been presented while discussing the earthquake cycles method of predicting earhquakes .

E. the unreliability of short-term earthquake predictions
laboratory evidence focusses on the effects of stress lead to precursory phenomena, not on the the unreliability of short-term earthquake predictions

The correct option is (B)

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26 Jun 2023, 22:26

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3. It can be inferred from the passage that one problem with using precursory phenomena to predict earthquakes is that minor tremors

A. typically occur some distance from the sites of the large earthquakes that follow them
no such fact presented in the passage

B. are directly linked to the mechanisms that cause earthquakes
foreshocks are not always followed by earthquakes -- as highlighted in the passage

C. are difficult to distinguish from major tremors
no such comparisons not drawn in the relevant portion of the passage

D. have proven difficult to measure accurately
difficulty in measurement for the minor tremors has not been discussed in the passage

E. are not always followed by large earthquakes
In paragraph 2 (lines 22-27) of the passage, the author alludes to the fact that 'these foreshocks indicate nothing about the magnitude of an impending quake and are indistinguishable from other minor tremors that occur without large earthquakes' -- highlights that such minor tremors are not always followed by earthquakes

The correct answer is (E)

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28 Jun 2023, 06:20

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4. According to the passage, some researchers based their research about long-term earthquake prediction on which of the following facts?

A. The historical record confirms that most earthquakes have been preceded by minor tremors.
opposite to this stem has been highlighted in the passage ie, precursory shocks are similar to other minor tremors that occur without large earthquakes.

B. The average interval between earthquakes in one region of the San Andreas Fault is 132 years.
That's just a fact presented in the passage. The research work was not based on this fact.

C. Some regions tend to be the site of numerous earthquakes over the course of many years.
ines 27-31 (2nd paragraph) clearly highlight : In the 1980s, some researchers turned their efforts from short-term to long-term prediction. Noting that earthquakes tend to occur repeatedly in certain regions,

D. Changes in the volume of rock can occur as a result of building stress and can lead to the weakening of rock.
mechanism described in these lines. Not used as a fact by the researchers for research about long-term earthquake prediction

E. Paleoseismologists have been able to unearth and date geological features caused by past earthquakes.
The work of palaeoseismologists have not been shown to assist research regarding preciction about long-term earthquake prediction

The correct option is (C)