Faultline fluid pressure during a magnitude-4 earthquake. Image: Weatherly & Henly, Nature Geoscience, 2013.
Want free gold? Here’s a surprising real-estate tip!
This is Sandra Tsing Loh with the Loh Down on Science.
Geophysicists in Australia were studying earthquakes. Earthquakes produce faults. Trace-element-laden water flows along them. In quartz veins that formed eons ago, gold often appears. But how exactly do those gold deposits form?
To find out, they used size measurements of actual faults. They plugged in scenarios of different magnitude quakes. They then analyzed this model . . . based on the mechanics of pistons.
Seems that, during earthquakes, fault fissures can expand instantly. A magnitude-2 quake can increase a fissure's volume 130! Expansion causes pressure to drop, and water in the fissure then expands to fill the space. Sometimes the water expands so much so fast it turns into vapor! It’s called “flash vaporization.”
Then, trace elements that had been dissolved in the water get concentrated. With repeated quakes, gold deposits build up along with various minerals.
Note to self: Buy property along San Andreas fault, wait for the Big One. Think less May Day than Pay Day! Eureka!
***** For more 90-SECOND SCIENCE FACTS, click here.*****
Thursday, from 2-3 p.m. on the LDOS blog: Sandra chats with author Po Bronson about his book NurtureShock.
Follow us on Twitter!