Scientist tracking...

Not in that sentence.

Jumanah1. Scientists tracking the movements of the earth's crust believe that a massive earthquake, knowns as "the big one", will eventually occur in southern California.

Either "A scientist" (if there is only one) or (more likely) "Scientists" in the plural.

Do you mean "scientist track the movements of..." is wrong?!

Yes.

Scientists [who are] tracking...

Think of it that way. For this sentence.

JumanahIs it correct to say "Scientist track the movements of..."?

Here are possible variations:

Scientists tracking the movements of the earth's crust believe that a massive earthquake, known as "the big one", will eventually occur in southern California.

Scientists track the movements of the earth's crust and

JumanahScientists tracking the movements of the earth's crust believe that a massive earthquake, knowns known as "the big one", will eventually occur in southern California.

~ Some scientists are tracking the movements of the earth's crust. Those scientists

Scientist track the movement of the earth's crust believing that a massive earthquake ..."
My teacher said "If you use "track" as a base form, the other verb which is " believe" should be in a gerund form" or the opposite."
Is she right?!

JumanahScientist track the movement of the earth's crust, believing that a massive earthquake .

'Believing' is a participle there, not a gerund.

I have no idea what the 'opposite' of a gerund is.

I have another question.
1.Sara always goes to the school believing that it's important for her.
Can you please tell me the name of the rule that is similar to the sentence?