Southern tunnels - main tunnel:

2 - bler144 - SmartyFartBlart - Human Paladin
3 - arsalan12 - Arsalan - Elven Mage
9 - MaxFulvus - Max, son of Fulvus - Dwarven Thief
26 - ciemnogrodzianin - Thulgrun the One-Eyed - Dwarven Warrior
28 - triock - Triock Ulagolor - Elven Paladin
30 - aRealCyborg - Kyp - Dwarf Ranger
41 - zlaywal - Zayd ibn Yasin - Human Ranger
43 - idbeholdME - Svartalf - Dwarven Battlemage
48 - babark - Babargh - Dwarven Cleric
52 - RedFireGaming - Roark - Elven Druid
70 - Lifthrasil - Thras - Dwarven Mage
72 - park_84 - Darrim - Dwarf Warrior
78 - CervelloYM - Cervello - Drow Battlemage
80 - Green_Hilltop - Eranear - Elf Paladin

Side tunnel:

5 - Sulibor - Dunward - Human Mage
15 - Lone_Scout - Says Beldarion - Human Warrior
22 - 01kipper - Kip - Halfling Brigand
29 - gogtrial34987 - Og'rialt - Dwarf Brigand
35 - jonridan - Aslain Melemir - Elven Thief
59 - Lemmus - Cicatrix - Drow Ranger
69 - alexandros050 - Rudy - Human Ranger

If you can repeat here your actions/ spell castings please. I will try to find them in the main thread but it is a bit of a mess over there and easy to miss stuff.

Aslain is walking and using his high perception to detect traps. Also, I took a torch to light the way.

The side tunnel crowd:

Ahead:
69 - alexandros050 - Rudy - Human Ranger: Entered on his/her own without waiting for the rest to arrange a party.

Party:
Front row:
35 - jonridan - Aslain Melemir - Elven Thief: Detecting traps and lighting the way
15 - Lone_Scout - Says Beldarion - Human Warrior: Sword in hand, ready for combat and trying to hurry the others.
Middle:
29 - gogtrial34987 - Og'rialt - Dwarf Brigand: Arranging stuff and detecting dangers. He also set a fire trap at the entrance of the tunnel, to prevent unwanted visitors to get to our backs.
Back:
5 - Sulibor - Dunward - Human Mage: Casting detect secret and with a wand ready for... something.
22 - 01kipper - Kip - Halfling Brigand: Listening and defending the rearguard.

Well, I'm not 100% sure of what everyone is doing exactly, but that's the arranged formation, unless someone says otherwise.

22 - 01kipper - Kip - Halfling Brigand - southern side tunnel

Everything stated above by Lone_Scout is true to my understanding as well. We are moving south now without further delay.

3 - arsalan12 - Arsalan - Elven Mage

I went to the main south tunnels and cast the spell 'Summon Monster'.

Another confirmation on the small tunnel crowd. Everything in #4 matches my notes.

80 - Green_Hilltop - Eranear - Elf Paladin first specified main tunnel, then after seeing your collapse tried to make for the small tunnel, if he could reach there before we moved out (so I could tell him how to avoid the fire trap), which he wanted confirmation from Doc on.
Now that he knows the main tunnel isn't blocked off, I don't know what his preference is.

Zayd ibn Yasin hurriedly pressing forward on the main tunnel in a foul mood. He swore anything within the range of his longbow will pay a price.

I've decided to go into the main tunnel after all, since it's not caved in, as I prefer larger space where I can manouever more. Otherwise I would've joined your party, you have a great team! :)

To the main team: I'm wearing full plate armour and have a medium shield, so if you want to, I can join the front line or help in the middle or back. Having more people in the front is always better, esp. when there's space behind us to allow the ones on the sidelines to move back when needed.

"Ah, have no fear brave human! During the goblin... troubles of 1201, I got in a lot of practice with my trusty chain! I could swipe a fly off your nose with this thing, without you feeling more than a light whoosh of air! Want me to demonstrate?" Og'rialt start to lightly twirl the chain around with a mischievous grin peeking out from under his full beard, and as he does so, he realizes that being in a small tunnel with solid stonework gives him feelings of home. He doesn't regret for a moment the decisions that led to his exile, but right in this moment, and despite all the worries about many claws approaching, being here in his natural element simply feels good to him.

(OOC: Doc confirmed that I can fight effectively with my chain from behind the front row without hindering you.)

I pick up an unlit torch from one of the walls of the tunnel and put it into my backpack.

I'm walking into the main southern tunnel. I greet the adventurers already there.

Roark, Elven Druid

Southern tunnel:

Wide and high the tunnel is poorly lit. What is currently visible is a trapdoor 20 feet down the tunnel, in the middle of the tunnel.
There are two doors just before the trapdoor, one in the left wall and one in the right wall.
There are two doors just past the trapdoor, one in the left wall and one in the right wall.

3 - Arsalan - Elven Mage casts Summon Monster, a 7 foot Gnoll appears beside him, snarling and snapping its jaws while it awaits instructions.

Side tunnel:

The tunnel has reasonable visibility, there are two doors further up the right wall of the tunnel. A third door has been discovered inbetween the original two.

35 - Aslain Melemir - Elven Thief starts checking for traps.

29 - Og'rialt - Dwarf Brigand sets a fire trap at the entrance to the tunnel being careful to tell his companions where it is. He stays alert for possible ambushes.

5 - Dunward - Human Mage casts detect secrets - a door has revealed itself between the two that were already visible.

A large crash booms from the chamber outside the tunnel.

22 - 01kipper - Kip - Halfling Brigand - southern side tunnel

I think we should (as a party) move forward and investigate the three doors.

After Aslain has finished checking for traps, assuming he finds none we can listen simultaneously at all three doors (Kip will volunteer to listen at the one furthest north; perhaps Og'rialt can take the middle/secret door and Aslain the southern door, to match our marching order?). If we don't hear anything of immediate threat, we should open the secret door (the middle door), Beldarion is probably the one to take the lead for that job?