"Without a doubt the earthquakes released stress on the fault. So what's next? Is there more stress that needs to be released along these complicated faults, or should Californians rest easy? "I'm not yet convinced of this, but I do think that this recent (geologically speaking) cluster of earthquakes in the ECSZ is very interesting," wrote Cooke, referring to 19 earthquakes within the zone. These two earthquakes could also be just another sign that more seismological action is starting to occur not along the infamous San Andreas Fault but rather in the so-called Eastern California Shear Zone (ECSZ). "This increases the challenge for seismic hazard forecasting because complex ruptures happen across multiple faults and impact wider regions," Cooke added. "Many of us are wondering if these complications are actually the norm and that our instruments 10+ years ago were not sensitive enough to pick up these complications," Cooke told Live Science in an email. "We don't have a lot of earthquakes in our record that show simultaneous slip on two perpendicular faults."Įven so, Cooke said many recent earthquakes have been a little messy, rupturing in a more complicated way than just an even slip on a single plane of faults. This is very interesting geologically, said Michele Cooke, a geoscientist at the University of Massachusetts - Amherst. In 2019, California was shaken by 1 quake of magnitude 7.1, 1 quake of magnitude 6.4, 7 quakes between 5.0 and 6.0, 98 quakes between 4.0 and 5.0, 888 quakes between 3.0 and 4.0, and 6913 quakes between 2.0 and 3.0. And part of that smaller event happened on an unmapped fault that trends NE-SW. The majority of earthquakes in Oklahoma are caused by the industrial practice known as 'wastewater disposal'. The largest known fracking induced earthquake in the United States was a M4.0 earthquake that occurred in Texas in 2018. "The earthquake on Thursday was more complex. The largest earthquake known to be induced by hydraulic fracturing in Oklahoma was a M3.6 earthquakes in 2019. Here's where things get interesting: The 7.1-magnitude earthquake rattled a fault within the Little Lake fault zone - cracks in this spot near Ridgecrest tend to run in the northwest-southeast direction. Susanne Jänecke, a geoscientist at Utah State University, described these fault systems as "hanging shoe organizers," where the sides, and tops and bottoms of the organizer would represent the various faults.
(In fact, the 6.4-magnitude quake began at a depth of 6.6 miles, or 10.7 km, while the epicenter of the bigger quake was much deeper, some 10.6 miles, or 17 km, beneath the surface.) Many are short, and because they are buried, we probably do not know them all." He added, "This area does not fit the textbook picture of sides of a plate sliding past one another," and instead the relatively short faults criss-cross each other on more than one plane. "The earthquakes of the 4th and 5th occurred in what we call a fault zone," Glenn Biasi, a geophysicist with the USGS in Pasadena, California, told Live Science in an email, "where many individual faults are active. The network of cracks in Earth's crust where the quakes occurred sits within the North American plate, which bumps up against the northwesterly moving Pacific plate.
0 kommentar(er)
