Read the following passage and answer the items that follow. Your answers to these items should be based on the passage only.

Passage 1

In 1971, researchers aimed to predict earthquakes by identifying short-term precursors like changes in seismic wave velocity. Dilatancy theory, based on lab observations, explained this: under stress, rocks first contract, then crack and expand, allowing groundwater in and weakening the rock. This process could cause seismic velocity changes and increased small tremors before quakes. Initial studies showed promise, suggesting identifiable precursors. However, later analysis proved disappointing. While unusual seismic waves were observed before some quakes, and most large earthquakes are preceded by minor tremors, these foreshocks are indistinguishable from regular tremors and reveal nothing about quake magnitude. The episode underscores the difficulty of using complex natural patterns to predict catastrophic events with precision, despite sound theoretical foundations.

Based on the above passage, the following assumptions have been made:

1.Laboratory observations of rock behaviour under stress could be directly and reliably extrapolated to complex geological systems in their entirety.

2."Precision" in earthquake prediction requires the identification of unique, unambiguous precursors that are consistently correlated with the main event's characteristics.

Which of the assumptions given above are valid?

(a)1 only

(b)2 only

(c)Both 1 and 2

(d)Neither 1 nor 2

Question

Read the following passage and answer the items that follow. Your answers to these items should be based on the passage only.

Passage 1

In 1971, researchers aimed to predict earthquakes by identifying short-term precursors like changes in seismic wave velocity. Dilatancy theory, based on lab observations, explained this: under stress, rocks first contract, then crack and expand, allowing groundwater in and weakening the rock. This process could cause seismic velocity changes and increased small tremors before quakes. Initial studies showed promise, suggesting identifiable precursors. However, later analysis proved disappointing. While unusual seismic waves were observed before some quakes, and most large earthquakes are preceded by minor tremors, these foreshocks are indistinguishable from regular tremors and reveal nothing about quake magnitude. The episode underscores the difficulty of using complex natural patterns to predict catastrophic events with precision, despite sound theoretical foundations.

 Based on the above passage, the following assumptions have been made:

1.Laboratory observations of rock behaviour under stress could be directly and reliably extrapolated to complex geological systems in their entirety.

2."Precision" in earthquake prediction requires the identification of unique, unambiguous precursors that are consistently correlated with the main event's characteristics.
 

Which of the assumptions given above are valid?

(a)1 only

(b)2 only

(c)Both 1 and 2

(d)Neither 1 nor 2

ONLiNE UPSC · Accepted Answer

Statement 1 is correct: The dilatancy theory, which "explained" the observed changes, was "based on lab observations." For researchers to aim to predict earthquakes using this theory, they must have assumed that these controlled laboratory findings could accurately model the much more complex and variable conditions of real-world geological fault lines. This is a significant extrapolation.
Statement 2 is correct: The disappointment arose because foreshocks, while common, are "indistinguishable from regular tremors and reveal nothing about quake magnitude." This implies that for "precision," precursors would need to be unique (distinguishable) and reliably correlated with specific outcomes (magnitude). The lack of these qualities led to the difficulty.

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