Hmm: Helium leak suggests new importance for LA-area fault zone; next ‘big one’ to be massive?

Hmm: Helium leak suggests new importance for LA-area fault zone; next ‘big one’ to be massive?
Scene from the movie San Andreas. (Image via Daily Mail)

[Ed. – Bonus: probability of the “next big one” within 30 years now up significantly.]

A huge fault in the Earth’s crust near Los Angeles is leaking helium, researchers have found.

They say the unexpected find sheds new light on the Newport-Inglewood Fault Zone in the Los Angeles Basin.

It reveals the fault is far deeper than previously thought, and a quake would be far more devastating. …

Using samples of casing gas from two dozen oil wells ranging from LA’s Westside to Newport Beach in Orange County, Boles discovered that more than one-third of the sites show evidence of high levels of helium-3 (3He). …

‘The Newport-Inglewood fault appears to sit on a 30-million-year-old subduction zone, so it is surprising that it maintains a significant pathway through the crust.’

Considered primordial, 3He is a vestige of the Big Bang, and its only terrestrial source is the mantle. …

An analysis showed that…CO2 [also present] was also from the mantle, confirming leakage from deep inside the Earth.

Blueschist found at the bottom of nearby deep wells indicates that the Newport-Inglewood fault is an ancient subduction zone – where two tectonic plates collide – even though its location is more than 40 miles west of the current plate boundary of the San Andreas Fault System.

Found 20 miles down, blueschist is a metamorphic rock only revealed when regurgitated to the surface via geologic upheaval. …

[T]he estimate for the likelihood that California will experience a magnitude 8 or larger earthquake in the next 30 years has increased from about 4.7% for UCERF2 to about 7.0% for UCERF3.

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