More earthquakes have hit in central Nebraska. The U.S. Geological Survey say that an earthquake with a magnitude of 3.1 hit around 4:48 p.m. Monday. With this most recent earthquake, there have now been a total of six earthquakes that hit that area in less than a week! Although earthquakes are not a new thing here in Nebraska, there have only been 46 since 1975.
Six earthquakes have shaken Nebraska already this week. That is really a lot knowing that just 46 hit the state since 1975.
The quakes are most likely due to fault lines that run a few miles underneath the ground. But it’s certainly not a fault that officials can map at the surface because if you know anything about this area of Nebraska, you know that there aren’t any rock-out crops and mostly when seismologists map faults they map them in bedrock.
Perhaps what the only thing that’s disconcerting about this is how little we know about the geologic structure underneath Nebraska.
Over the last four decades, earthquakes have happened all over the state, but never anything greater than a 4.3 magnitude. Every time there’s an earthquake, however weak it happens to be, it’s one more data point on the map, and one more small piece of data that helps us understand the geology of Nebraska better.
Yesterday, I have also reported a story about a mysterious swarm of earthquake that hit McAdam in New Brunswick, Canada… A place where there is no fault lines.
A village in New Brunswick has been shaken by at least 14 earthquakes over the past 17 days — and nobody knows what’s causing them. This is not the first time the community has trembled like this. Towards the beginning of 2016, McAdam experienced more than 100 small earthquakes, which shook homes and broke windows. Like the most recent swarm of tremors, no scientific explanation was ever found.
According to data from Natural Resources Canada, there have been 23 earthquakes in the province over the past 30 days. That includes 14 in the vicinity of McAdam between March 27 and April 3 that have ranged in magnitude from 0.2 to 2.6. More than half of the earthquakes, he added, have occurred in the middle of the night at the relatively shallow depth of 600 metres.
“We’ve had about three, I think, that came in around 2.6 — so those ones you feel and you hear. So you’d be sleeping in bed and all of a sudden, you’d hear this bang… And you’d sit right up and say, ‘There’s another one,’ and then you’d hear another little bang, bang as they kind of went away.”
These earthquakes are very close to the surface… And that’s why people hear them besides feeling them.
Nobody knows what is going on
McAdam sits near the province’s western edge, close to its border with Maine. There are no well-defined fault lines in the area, which makes the earthquakes all the more puzzling to researchers.
“In terms of what is exactly triggering them, this is not understood still,” University of New Brunswick geology and engineering professor Karl Butler told CTV Atlantic.
A seismograph does operate from McAdam, sending tremor information on to scientists in Ottawa. Better equipment, Butler suggested, could help solve the mystery.
“In McAdam, we do have a permanent station there, but not a small array like we did previously,” Butler said. “So they can’t locate the events as accurately.”
Figuring out what’s going on underneath McAdam would likely require significantly more research, Burke added.
No comments:
Post a Comment