Power blackouts and poorly-thought-out evacuation alert systems have left Californians without critical information during natural disasters in the past.
But there are some free apps for your phone, numbers to text, systems to register for and technology to buy that could ensure that you have the most accurate and up-to-date information when disaster strikes, even during a power blackout.
An unusually shallow earthquake triggered by hydraulic fracturing in a Chinese shale gas field could change how experts view the risks of fracking for faults that lie very near the Earth’s surface.
In the journal Seismological Research Letters, Hongfeng Yang of The Chinese University of Hong Kong and colleagues suggest that the magnitude 4.9 earthquake that struck Rongxian County, Sichuan, China on 25 February 2019 took place along a fault about one kilometer (0.6 miles) deep.
The earthquake, along with two foreshocks with magnitudes larger than 4, appear to be related to activity at nearby hydraulic fracturing wells. Although earthquakes induced by human activity such as fracking are typically more shallow than natural earthquakes, it is rare for any earthquake of this size to take place at such a shallow depth.
“Earthquakes with much smaller magnitudes, for example magnitude 2, have been reported at such
Precariously balanced rocks, or PBRs, can be found throughout the world, identified by slender rocks balanced on a pedestal boulder.
There are a few ways they can form. PBRs can be the result of landslides or retreating glaciers, which deposit the rocks in the unordinary formations. They can also manifest when softer blocks erode, leaving the stronger ones behind.
While they look delicate, some of them — like the Brimham Rocks in Yorkshire or Chiricahua National Monument in Arizona — have survived countless earthquakes over thousands of years. Now, researchers from Imperial College London are taking a closer look at PBRs, because they are showing promise in helping scientists determine earthquake hazards more accurately.
The study’s authors say the construction of PBRs provides insight on the upper limit of earthquake shaking that has occurred in the area.
Earthquakes can be abrupt bursts of home-crumbling, ground-buckling energy when slices of the planet’s crust long held in place by friction suddenly slip and lurch.
“We typically think of the plates on either side of a fault moving, deforming, building up stresses and then: Boom, an earthquake happens,” said Stanford University geophysicist Eric Dunham.
But deeper down, these blocks of rock can slide steadily past one another, creeping along cracks in Earth’s crust at about the rate that your fingernails grow.
A boundary exists between the lower, creeping part of the fault, and the upper portion that may stand locked for centuries at a stretch. For decades, scientists have puzzled over what controls this boundary, its movements and its relationship with big earthquakes. Chief among the unknowns is how fluid and pressure migrate along faults, and how that causes faults to slip.
A new physics-based fault simulator developed by Dunham