Complex sentence: He explains the threat of water not just escaping when pouring through the crevasse, but creates friction and extends the wires connecting between the crevasse and the mountain, causing them to be weakened.
Split into simpler sentences: He explains the threat of water not just escaping when pouring through the crevasse. Instead, he claims that they create friction and extends the wires connecting between the crevasse and the mountain, causing them to be weakened.