The answer that agreed in general from this question was because the absence of ground water. The ground water made the land still in this position. When they have gone, the land above the water would decline day by day.
But, Sri had another response. She said that the land subsidence in Tambaklorok occured since there were construction project of factory beside the Tambaklorok settlement.
"In addition of the factory building weight, that factory was built in ex-marine ponds," she said.
Sri could be wrong. She was not a researcher. She was a student activist, and now be one of big political party cadres in Indonesia. But she had been living in Tambaklorok from her birth, almost 40 years.
Related with the construction project, Ani Faridah had another story. She said that there were project construction activity from the government. That project impacted the big shaking that implied to all houses from Tambaklorok settlement. The Government then fixed that problem by put vibration dampers in some points.
"It could be one of factor of land subsidence here," she said.
Fortunately, the government was not stay there and did nothing. Sri said that they made a high tax regulation that addressed to that factory. The impact was the factory stopped all their activity at that area, the owner moved the factory to the east, Demak. They had still to pay the tax in Demak, but not as high as in Semarang.
"But the land is already down day by day, and the tidal flood already come regularly," she said. (*)