The ground shook again.

The tremor was brief, like something on the seabed burping. Chen Hao stood by the south wall, still clutching half a burlap sack, sweat dripping from his nose. He didn't move, but simply tossed the sack to the ground and took a breath.

"As long as the wall didn't collapse, that's fine," he said. "If it can't even withstand this aftershock, then all that effort to withstand the wave was for nothing."

Nana stepped out of the waterproof door, her blue eyes flashing a few times as data streams rolled across her vision. She walked to Chen Hao's side, her voice steady: "The structural stress has returned to a safe range, and the container defense line has met the pressure resistance standards."

“That’s good.” Chen Hao wiped his face. “But we people aren’t walls. Walls can stand, but people need to drink water.”

He finished speaking and turned to walk into the base. Blood was still seeping from the wound on his right arm, mixing with muddy water as it dripped down, but he ignored it. The corridor lights flickered on and off; emergency power hadn't been fully restored.

Susan leaned against the door of the medical room, holding an empty medicine box and looking down at a list. Carl squatted beside her, tightening the buttons on his tool bag, his face covered in dust.

“Two of the water purification modules are broken,” Susan said, looking up. “Three of the water storage tanks are cracked, and some of the remaining water has leaked into the sea.”

"How much more can you drink?" Chen Hao asked.

“Forty percent,” Nana continued. “One-third of them tested positive for excessive salt and heavy metals, making them unsuitable for drinking without treatment.”

Chen Hao was silent for a few seconds, then smiled: "It means we might survive now, or we might die of thirst."

“Accurate,” Nana said.

"Then let's not wait any longer." Chen Hao slapped the wall. "We have to find a new water source. The strata have changed after the tsunami, and the wellheads may all be ruined. If it doesn't rain soon, we won't last three days."

Susan frowned: "Everyone has just worked for six hours and is at their physical limit. They need to rest for at least a few hours."

“We only have a few hours left.” Chen Hao shook his head. “A third wave of the tsunami could come at any time. If it comes again, all the groundwater will be filled with saltwater. At that time, we won’t even have water to wash our hands, let alone drink water.”

Carl stood up, patted the mud off his pants, and said, "Wow. I can still walk."

“I’ll go too.” Susan stuffed the list into her pocket. “I can see signs of vegetation transpiration; wet areas will reflect light.”

Nana brought up a map projection, and the light spot fell on the ground. She pointed to the northeast: "There is a low-lying area within three kilometers, which has historically been a rainwater collection area. The geological permeability is relatively high, and there is a 67% probability that there is shallow underground water flow."

"It sounds like an advertising slogan," Chen Hao said, "but it's better than just wandering around aimlessly."

“I suggest working in pairs,” Nana said. “Carry a detector, an empty water bag, and basic protective gear. Report your location every half hour to avoid losing contact.”

“Okay.” Chen Hao nodded. “You two go. Nana and I will stay here to check the supplies, repair the water purification equipment, and keep an eye on the data outside.”

Susan didn't speak, silently checking her backpack. Carl stuffed the welding torch and rope inside, and added a bottle of spare fuel.

Nana walked over and put a spare battery into Carl's bag: "The communicator signal is unstable, this will extend its usage time." She then handed Susan a printed sheet of paper, "This is a geological model of the surrounding area, to avoid high-risk areas of collapse."

"Thanks." Susan accepted the money.

Chen Hao stood at the door, not saying much, but simply patting Carl on the shoulder with one hand and putting the other on Susan's shoulder: "Come back alive. Don't be stubborn. If you can't find her, come back. Don't push yourself."

“I know.” Carl grinned. “I’m not going to die.”

“Then you better remember this,” Chen Hao said. “Last time you said ‘just go take a look,’ and you almost got swept away by the waves.”

“That was an accident.” Carl slung his bag over his shoulder. “This time I brought a rope.”

Susan also put on her equipment and adjusted the switch on the detector. Her hands were shaking a little, but her movements were steady.

"Ready?" Chen Hao asked.

The two nodded.

Let's go.

They walked through the main passage, wading through the puddles towards the exit. When the door opened, the sky outside was gray, the fog was heavy, and the air was damp and cold. The muddy road still bore the tracks left by the carts that had been used to transport materials the night before, now turned into gullies by the rain.

Carl walked ahead, his steps steady. Susan followed behind, holding a detector in her hand, her eyes scanning the vegetation on both sides.

Chen Hao and Nana stood at the door, watching them walk away.

"Can they do it?" Chen Hao asked.

“The probability is 73 percent,” Nana said, “provided there is no secondary geological change.”

"It's only slightly more accurate than flipping a coin," Chen Hao sighed. "But we have no other choice."

He turned and walked back: "Let's go to the warehouse first and divide up the remaining compressed rations. Every bit saved counts."

"The food loss rate is 28 percent," Nana said as she walked. "The main losses come from water entering the grain warehouse, which caused severe mold growth."

"Then let's allocate quotas based on the number of people," Chen Hao said. "Priority will be given to the construction team, as they expend a lot of physical labor."

“The medical kit was also damaged,” Nana added. “Gauze and disinfectant were scattered, and some medicines became damp and ineffective.”

"Write this down." Chen Hao walked into the warehouse and opened the metal cabinet. "I'll see if we can make do with a substitute later."

He bent down and rummaged through the latrine, pulling out several well-sealed packets of biscuits and two bottles of vitamin pills. His fingers paused abruptly when they touched a box of bandages.

“My injury…” he glanced at his right arm, “looks like it needs to be bandaged.”

“I recommend immediate treatment,” Nana said. “The wound remains exposed to the contaminated environment, increasing the risk of infection.”

"I know." Chen Hao stuffed the bandage into his clothes. "We'll talk about it later. There's too much to do right now."

He carried the supplies out of the warehouse and headed straight for the main control area. He encountered several workers along the way and casually distributed some biscuits to them.

"I'm eating sparingly," he said. "I don't know when the next meal will be."

At the control panel, Nana had already connected to the energy network, and various data were flashing on the screen. She was running three diagnostic programs simultaneously, and the repair progress bar for the water purification equipment was slowly climbing.

"The estimated repair time is two hours and fourteen minutes," she said.

"It's too slow." Chen Hao put the supplies in the corner. "Is there any way to speed it up?"

“The filter needs to be cleaned manually,” Nana said. “There’s no one available to clean it right now.”

"I'll go." Chen Hao put down his backpack. "Anyway, I'm not that busy right now."

He opened the maintenance panel and reached inside to remove the blockage. His fingers touched a clump of wet mud and bits of plastic, which smelled foul.

"Who designed this thing?" he frowned. "Why didn't you call the police when it's blocking the road?"

“The design lifespan is ten years,” Nana said. “It has been in use for eight years and seven months so far.”

"No wonder." Chen Hao pulled out a dark, grimy object. "It's almost expired, and the system is starting to slack off."

He continued cleaning, his movements practiced and efficient. Although he was usually lazy, he never hesitated when it came to getting things done.

Nana suddenly looked up: "Received Karl's first location report. We have traveled 800 meters and found nothing unusual."

"That's good." Chen Hao shook the dirt off his hands. "Let them walk slowly, don't rush them."

Susan asked: "Should we collect soil samples?"

“Collect it,” Chen Hao said. “Bring it back; Nana can analyze it.”

He stood up and stretched his shoulder. The wound started to hurt again, but he didn't show it.

"What's next?" Nana asked.

“Wait.” Chen Hao leaned against the wall. “Wait until they find water, or come back empty-handed. We’ll repair the equipment, distribute the food, and guard the base. That’s what we’ll do.”

“You look very tired,” Nana said.

"Nonsense." Chen Hao rubbed his eyes. "Who isn't tired? The problem is, even after you're exhausted, you still have to work."

He walked to the window and looked out at the fog. The muddy road was mostly obscured by the fog, and no one could be seen.

"I hope they don't run into any trouble," he said.

"Trouble will always come," Nana said. "The difference lies in whether you can handle it."

“You’re starting to sound more and more human,” Chen Hao chuckled. “Before, you’d only say things like ‘what’s the probability?’”

“With enough samples observed,” Nana said, “the conclusions will naturally change.”

Chen Hao didn't say anything more. He sat back down in his chair and opened another maintenance interface.

Time passed little by little.

The lights in the control room have stabilized a bit. The progress bar for the water purification system has jumped to 60%.

There was no news from outside.

Until the walkie-talkie crackled to life.

“This is Carl.” The voice was broken. “We’ve reached the edge of the low-lying area and found the ground damp. The detectors are responding. We’re moving forward.”

Chen Hao grabbed the walkie-talkie: "Keep your distance, watch your step. Don't fall into the pit."

“Understood.” Karl paused. “And… in this forest, the trees aren’t falling quite right.”