I don't know the surah's but i do know one of the ayaat that explains why.. . وَمَآ أَصَـبَكُمْ مِّن مُّصِيبَةٍ فَبِمَا كَسَبَتْ أَيْدِيكُمْ وَيَعْفُواْ عَن كَثِيرٍ
And whatever of misfortune befalls you, it is because of what your hands have earned. And He pardons much.