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?

Question

Autumn Mcfarland

Physics

21 January, 18:20

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?

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Answers (1)

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Janelle Clements · Answer 1

v = 1.36 cm / y

Explanation:

For this exercise we must assume that the displacement of the plates is constant over time, so we will use the kinematic relationships for the uniform movement

v = d / t

We reduce the quantities to the SI system

d = 320 km (1000 m / 1km) (100 cm / 1 m)

d = 3.2 107 cm

let's calculate

v = 32.107 / 23.5 106

v = 1.36 cm / y