To obtain the It’s Not Your Fault side quest in Dead Island 2, speak with Luciana at Emma’s house in Bel-Air. For this quest, you’ll need to head to the sewers access point just south of Emma’s.
Just outside interact with the Seismometer Placement journal on the ground by the white truck.
Afterwards, head inside the pipe. Make your way through the sewers, passing Patton’s place, to reach the Brentwood Sewer. Once in the Brentwood Sewer, head north then look to the left down a short tunnel to find the Seismometer Key Alpha.
Use this key on the box next to it to recover the data from the first seismometer. Continue deeper into the sewer to find the Seismometer Key Beta next to a corpse.
Use this key to unlock the box on the other side of the room behind a grate.
Continue to the next room and head up the stairs. Enter the room at the top to find Niran’s Note on the table.
Head underneath the room and open the door. Head a short ways down the hallway to find Eli’s Note next to a corpse.
Head deeper down the hallway to come to a fire puzzle. Turn off the gas then proceed forward. Take the first right to find a room with sludge. You now have the fun task of sifting through it! The key can be found on the right side of the sludge down the tunnel.
Now that you have the key, return to the room above where you’re at where you found Niran’s Note. A Butcher now awaits your return. Take it out then loot the chest! With one more seismometer to go, continue deeper into the sewer. Along the path you’ll find Fieldnotes Journal.
Continue on and enter the Main Septic Tank. Defeat the Seismologist and gather the Seismometer Key Delta. The box to unlock is found nearby.
Afterwards, return to Luciana at Emma’s and speak with her to complete the quest. As a reward, you’ll receive 3,500 XP and a Big Shot (pistol).