grammar
''To the surprise of engineers and geologists''(A), ''in the year''(B) following the ''completion''(C) of the Hoover Dam, thousands of local earthquakes ''recorded''(D)

How to correct this sentence and please explain it

Question

grammar
''To the surprise of engineers and geologists''(A), ''in the year''(B) following the ''completion''(C) of the Hoover Dam, thousands of local earthquakes ''recorded''(D)

How to correct this sentence and please explain it

Answer

Your sentence doesn't have a verb that fits its tense. Add "were" before "recorded". So: "... thousands of earthquakes were recorded."
Your sentence doesn't have a period. Add one.

That is everything that is wrong with the sentence.