The side slope at the exits of the diversion tunnels of Geheyan hydropower station is a man-made high and steep one.

清江隔河岩水利枢纽电站引水洞出口是由自然边坡改造而成的高陡人工边坡，具上硬下软岩体结构。

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Another Thai survivor stuck on the "critical side" of the volcano awaits rescue, he said, because the steep slope and high elevation prevents a helicopter landing.

WSJ: Guides Recall Escape From Philippine Volcano

Another Thai survivor stuck on the "critical side" of the volcano was awaiting rescue, he said, because the steep slope and high elevation prevents a helicopter landing.

WSJ: Guides Recall Escape From Philippine Volcano