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The Pinnacles and Neenach volcanics are 23.5 million-year-old andesite to rhyolite outcrops, on either side of the San Andreas Fault, today separated by ~320 kilometers. If they were originally products of the same eruptive center, they have been offset along the San Andreas Fault by 320 kilometers in 23.5 million years. What is the rate of offset in centimeters per year?