1)
Why should they sound the Shofar in Tziyon?
1.
Radak (1): To arouse people to repent.
2.
Malbim: Until now, he discussed repenting to nullify the decree. Now he discusses after the locusts already destroyed the land. He informs that also now there is a solution that they will leave the land. They should be Toke'a in Tziyon to gather the nation. He does not say to blow Teru'ah to arouse fear - they are already terrified, for the affliction already came!
2)
What do we learn from "Kadeshu Tzom Kir'u Atzarah"?
1.
Malbim: Initially (1:14), Kohanim decreed a fast and an assembly. Now it says that the nation will be aroused to do so after the evil came.
