It's been nearly two years since the South Napa Earthquake rocked the North Bay region — but the revelations keep on coming.
Scientists say data from earth movements that occurred after the major shaking stopped show helter-skelter patterns unlike anything they've seen before.
Field teams noted early on that the Napa quake of August 24, 2014 did an unusual amount of damage for a magnitude-6 temblor — and that the event was followed by significant "afterslip," when the ground keeps moving (albeit a lot more slowly) after the main event.
What surprised geologists analyzing data in the months to follow was the variety of afterslip, which was greater in some places than others, and moved faster in some spots.
"We found this fault shows multiple slip behaviors at different times," says Gareth Funning, a geophysicist at UC Riverside and lead author on the study. "We'd not seen anything quite like it before."