What does the author mean when he says "the earth ran amok"?

When the author says "the earth ran amok", he means the earth was total chaos, that it had no control as it usually would with "normal" weather or "normal" conditions.

Explanation:

During 1930, there was a severe dust storm that damaged the agriculture of America and Canada. The agricultural land became drought due to this dust. The drought-stricken Southern Plains region of the United States was named as dust bowl.

The author says "the earth ran amok" on seeing the dust bowl. That means he says that the land affected with the dust storm had so much dirt and mud as if they were in amok.