Psalm 46:2 New English Translation

²For this reason we do not fear^[a] when the earth shakes,^[b]
and the mountains tumble into the depths of the sea,^[c]

Psalm 46:2 tn The imperfect is taken in a generalizing sense (cf. NEB) because the situation described in vv. 2-3 is understood as symbolizing typical world conditions. In this case the imperfect draws attention to the typical nature of the response. The covenant community characteristically responds with confidence, not fear. Another option is to take the situation described as purely hypothetical. In this case one might translate, “We will not fear, even though the earth should shake” (cf. NIV, NRSV).
Psalm 46:2 tn The Hiphil infinitival form is normally taken to mean “when [the earth] is altered,” being derived from מוּר (mur, “to change”). In this case the Hiphil would be intransitive, as in Ps 15:4. HALOT 560 s.v. II מור emends the form to a Niphal and derives it from a homonymic root מוּר attested in Arabic with the meaning “shake.”
Psalm 46:2 tn Heb “heart of the seas.” The plural may be used for emphasis, pointing to the deepest sea. Note that the next verse uses a singular pronoun (“its waters,” “its swelling”) in referring back to the plural noun.

New English Translation (NET)