A quiet Alaska fault is missing the fluids scientists expected – and it’s changing what we know about earthquake zones |
Not all earthquake faults behave the same. Some stick and snap, causing earthquakes. Others move slowly over time.
For years, the leading explanation for slow-moving faults has been that high-pressure fluids along the fault lubricate it, allowing the slabs to slide steadily rather than building up stress until that stress is eventually released in a large, destructive earthquake.
But in a new study of the Shumagin Gap, a quiet section of the Alaska-Aleutian subduction zone – the area where one tectonic plate dives below another – my colleagues and I found that the fault does not contain enough fluid to explain why it slides slowly. Scientists may need to rethink this assumption about subduction zones around the world.
Pinning down why faults creep matters for how scientists build models of the world’s most powerful earthquake zones to assess long-term earthquake and tsunami hazards, from Alaska to Japan to the Pacific Northwest. Knowing how earthquakes are likely to behave is essential for helping communities decide where and how to build homes and other infrastructure so they can withstand an earthquake and tsunami.
How earthquakes happen along faults
An earthquake fault is a break in Earth’s outer rock layer where two blocks of rock slide past each other. The way they slide determines what kind of shaking, if........