Earthquakes around the world

Anomalous seismic activity recently in South Korea and Cuba:

Seismologists in South Korea are concerned about an unusual rash of earthquakes that have shaken the peninsula in recent weeks, with some suggesting that this sudden upsurge in seismic activity might be a precursor to a major — and potentially very destructive — earthquake.
...
But of even deeper concern to the experts have been the more than 400 seismic tremors since April 26 in a single area in South Jeolla Province, in the far south-west of the peninsula.

The region has not reported seismic activity since the government first began collating data in 1978.
...
"We have been monitoring the South Jeolla events closely because they are very unusual and have been happening in a very short space of time," said Hong Tae-kyung, a professor of seismology at Yonsei University in Seoul.

"It is also unusual because they are happening in a very small area and they are much deeper than usual," he said, adding that quakes on the peninsula usually occur at a depth of around 10 kilometers (6 miles). These latest tremors are happening 20 kilometers beneath the surface.
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www.dw.com

Could a major earthquake soon strike South Korea? – DW – 05/20/2020

The Korean Peninsula is not typically an area of high seismic activity, but seismologists have been rattled by a recent series of small tremors that they warn could be a sign of a bigger earthquake to come.
www.dw.com www.dw.com



More than 20 earthquakes, some of them perceptible, and a tornado that caused material damage, were reported this Sunday in eastern Cuba.

According to the National Center for Seismological Research (CENAIS), until 7:30 pm (local time), 21 telluric movements had been registered in the eastern part of the island, "some of them perceptible by the population," in what is classified as "anomalous seismic activity."
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oncubanews.com

More than 20 earthquakes and a tornado in eastern Cuba

More than 20 earthquakes, some of them perceptible, and a tornado that caused material damage, were reported this Sunday in
oncubanews.com oncubanews.com
 
Kamina, the capital city of Haut-Lomami Province in DRC got a hit:

M 5.2 - Africa Democratic Republic of the Congo [Katanga] Kamina

Preliminary Earthquake Report:
Date/Time: 21.05.2020 12:57:33 UTC
Magnitude: M 5.2
Mercalli Scale: 5
Depth: 10 km
Coordinate: 9° 39.426, 23° 58.656

Additional data:
Local time in the epicenter: Thursday, May 21, 2020 at 14:57 in the afternoon at epicenter
Continent: Africa
Country: Democratic Republic of the Congo [CD]
State: [Katanga]
Location: 146.00 km (90.72 miles) . of Kamina, [Katanga]
Population: 73557 person(s)
 
Agron said:
Kamina, the capital city of Haut-Lomami Province in DRC got a hit:

M 5.2 - Africa Democratic Republic of the Congo [Katanga] Kamina

Preliminary Earthquake Report:
Date/Time: 21.05.2020 12:57:33 UTC
Magnitude: M 5.2
Mercalli Scale: 5
Depth: 10 km
Coordinate: 9° 39.426, 23° 58.656

Additional data:
Local time in the epicenter: Thursday, May 21, 2020 at 14:57 in the afternoon at epicenter
Continent: Africa
Country: Democratic Republic of the Congo [CD]
State: [Katanga]
Location: 146.00 km (90.72 miles) . of Kamina, [Katanga]
Population: 73557 person(s)
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That's no where near a fault line? Why would an earthquake occur there?

I thought earthquakes only occured at or near fault lines?!?!
 
SOTTREADER said:
Big earthquake in Nevada USA. M6.2

No doubt this will make some news if it hit a populated region.

View attachment 36278

Couple of after shocks after at over M5.
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Tonopah is home to the Tonopah Test Range, home of the U.S. Air Force's test site of experimental and classified aircraft and famous for its connection with Area 51 enthusiasts.

Accuweather

Inquiring (though simple) minds would like to know:

Could it have been an explosion at the local deep underground military base there?

Seismographs across the region detected the initial earthquake and subsequent aftershocks...
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Screen-Shot-2020-05-15-at-12.44.34-PM.png



An early Friday morning earthquake near Tonopah, Nevada, was strong enough to be felt over 300 miles away in areas such as Bakersfield, California. The 6.5 magnitude quake struck at 4:03 a.m., PDT, according to the U.S. Geological Survey and had a depth of 2.5 miles. The USGS upgraded the quake’s magnitude to 6.5 from 6.4 about an hour after the initial strike.
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5.6-magnitude quake hits Mid-Indian Ridge: USGS
May 24, 2020
NEW YORK, May 23 (Xinhua) -- An earthquake with a magnitude of 5.6 jolted Mid-Indian Ridge at 23:02:28 GMT on Saturday, the U.S. Geological Survey said.

The epicenter, with a depth of 10.0 km, was initially determined to be at 14.812 degrees south latitude and 66.6823 degrees east longitude.
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5.9-magnitude quake hits Southern Mid-Atlantic Ridge -- USGS
May 24, 2020
BEIJING, May 24 (Xinhua) -- An earthquake with a magnitude of 5.9 jolted Southern Mid-Atlantic Ridge at 02:52:23 GMT on Sunday, the U.S. Geological Survey said.

The epicenter, with a depth of 10.0 km, was initially determined to be at 47.4139 degrees south latitude and 12.2226 degrees west longitude.
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5.5-magnitude quake hits 125km SW of Mapastepec, Mexico -- USGS
2020-05-24
BEIJING, May 24 (Xinhua) -- An earthquake with a magnitude of 5.5 jolted 125km SW of Mapastepec, Mexico at 03:52:22 GMT on Sunday, the U.S. Geological Survey said.

The epicenter, with a depth of 15.79 km, was initially determined to be at 14.6838 degrees north latitude and 93.7728 degrees west longitude.
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Aeneas said:
This last week the world seemed more active, at least in the usual map area that I follow.
All in all, there were 14 earthquakes equal or greater than 4.5 in the map area. The greatest being 6.5 in Nevada, which then triggered a number of strong aftershocks. The biggest earthquake worldwide was a 6.6 in the ocean near the Solomon Islands.
Of all earthquakes, 2832 out of 3317 fell in the map area seen below.
Percentage: 85.4%
Click to expand...
Again a week of a general increase in activity. Even if our usual map area will steal the picture, of interest was also the continuation of medium sized earthquakes in the south of Greece. The biggest earthquake worldwide was a 6.1 off the coast of Mexico.

Concerning the map area, then 10 earthquakes out of 97 worldwide, equal or greater to 4.5 fell in the area.
Of all earthquakes, the number was 4260 out of 4694 of which the vast majority fell in the southern part of the map area.
Percentage: 90.8%
Earthquakes 7 days to May 24th 2020.gif

Regarding Greece, then the activity started 3 weeks ago, May 2nd, with a 6.6 magnitude earthquake. For comparison with the North American map area, then the area around Greece, had 14 out of the 97 earthquakes equal or greater to 4.5 but only 40 of all earthquakes worldwide of all sizes. In percentage that means 14.4% of the big earthquakes, but only 0.9% of all earthquakes. This highlights to me as mentioned before, that the situation in North America is different than elsewhere and that a tension is being released in small earthquakes, but not in big ones, which probably could lead to the build up for a bigger one as small earthquakes just don't release much tension compared to medium to big earthquakes. Again, that is just speculation on my part and I have no professional training in seismology whatsoever, just a little curiosity.

Here is the map area for Greece showing the 14 quakes (and 34 for the last 30 days).
Earthquakes in Greece 7 days to May 24th 2020.gif
 
The largest mining quake recorded in Sweden happened on the 18 of May. I used Google translate to translate the following article, but it doesn't get every translation right, so I changed a little. But there are probably more miss translations anyway.

www.aftonbladet.se

Hotet från underjorden: Lät som att en bomb exploderade

KIRUNA. Kirunaborna vaknar klockan tre på natten och har inte hört något liknande. Måndagen den 18 maj rasar tavlor från väggar, sängar flyttar på sig och höghu
www.aftonbladet.se www.aftonbladet.se

The threat from the underground: Sounds like a bomb exploded

Kiruna. The Kiruna residents wake up at three in the night and have heard nothing like it. On Monday, May 18, paintings collapse from walls, beds move, and high-rise buildings sway. The bang is the largest mining quake ever in Sweden. But there are worse threats to LKAB, the job and Kiruna.

In a coffee room 814 meters underground, automation electrician Jonny Kumpula sits in a sofa and watches as a colleague fills water in the coffee maker.
It sounds like a bomb is exploding behind his back. Jonny Kumpula falls down from the sofa. The colleague drops the balance and spills water over the floor. Everything swings. They sit in a washing machine during a thunderstorm.
When the boards release from the walls, the colleague gets enough and says:
"It's time. Now we leave. "
They put on the mining helmets and run to the car. On the way up, they don't say much to each other. But they have time to think some when they look up at the roof. Now the mountain comes down, now we stay here.
- I just wanted to get up fast as hell and see the light in the tunnel, says Jonny Kumpula.

"Like a shotgun"
Meanwhile, many newly awakened Kiruna residents are rubbing their eyes. They basically live on an ore mine and are used to it grumbling in the ground, but what was that?
It was the biggest quake in a Swedish mine ever. The seismological event measures 4.9 on the Richter scale.
Thirteen people are down in the mine during the quake, and all of them can go undamaged to their collection points. They have no idea of any collapse and damage underground. But in a control center, Jonny Kumpula looks at a monitor that shows a tapping group where the ore is dropped into train carriages.
That part of the mining is automated. There are no people there.
- It looked like a shotgun. It had sprayed stone right out of the wall.

Hours away from a disaster
This is the first time that LKAB evacuates the mine and makes a total downtime due to a quake.
Nothing like that has happened in 130 years.
The state-owned mining company is investigating the extent of the damage. Some areas cannot reach them until the seismic activity in the rock has calmed down. It is possible to open the mining on a small scale relatively quickly, but it will take weeks before the operation is in full operation again.
LKAB was also lucky. If the earthquake happened in the morning when more than 300 people are underground, no great imagination is needed to imagine the disaster.
"It is an exceptionally powerful event," says Fredrik Björkenwall, the acting press officer at LKAB.
The question is, is it even possible to guarantee that the rock will never collapse?
- I say this: we can guarantee that we do everything we can to make sure that it does not become rock outfall, that is, rocks and stones collapse from the walls. It is also important to point out that these compositions are not dangerous if you are above ground. They do not threaten the inhabitants and the buildings.

A nasty logic
Regarding safety, the union is in agreement with the employer. No mine in the world can be 100 percent sure.
- It's like saying we should have zero vision on the roads. Will never happen until we do not drive ourselves, says Anders Elenius, chairman of the mine.
The deeper LKAB bursts and digs in the ground, the greater the tension in the rock. The greater the stresses in the rock, the more the risk of stronger discharges increases as the rock smoothes the pressure. The larger the discharges, the more dangerous it will be for the miners. That is the bitter logic of mining in Kiruna right now.
No one knows if the quake was a one-off event. Nobody knows if and when a similar bang will happen again.
- More such tremors risk adversely affecting the Kiruna residents. LKAB probably cannot afford so many fatal accidents, says Gunnar Selberg (C).

The ravine just grows
The voltages above ground are also large. The feud between LKAB and the municipality is bitter in 2020, which is due to the urban transformation.
As the ore body leans under Kiruna, parts of the city must move. Several of the city's landmarks have already been demolished, a few lakes have pumped away and the railroad has been moved. The only thing left of the old town hall is the belfry. The giant clock stands at the new town hall in Kiruna's new center, which is being built at the old Toullavaara mine, several kilometers away from the present city center.
The most noticeable change is the area in front of the mining mountain and the LKAB office. Where there used to be road, footpath and land, it is a deep gorge. Many in Kiruna call it the pit. In the United States it had been a canyon.
The gap follows the ore body. When LKAB picks out rocks in the underground, the ground slowly falls down and collapses. At the northern tip of the ravine, LKAB wants to mine more ore over a kilometer underground, but the municipality has not approved the permits.
LKAB and the municipal council do not agree on the costs and details of the urban transformation. LKAB thinks that they have paid enough and met the requirements, the municipality does not agree. The delay has meant that LKAB expects to produce less ore, which means that they can be forced to notify staff already this fall.
- LKAB will manage the corona, but we will not survive the municipality, says Anders Elenius.

"Must have a plan B"
Gunnar Selberg is of a different view. He says there is plenty of time left, that they will have the same time. But he is worried that it will be too expensive for the Kiruna residents.
- The municipality must ensure that we survive the urban transformation. It is actually even more important for the Kiruna residents. We let LKAB and the state demolish our city. Then it is not reasonable for us to have to pay this with higher taxes, or not have the necessary community services left. Development must go before decommissioning.
There is another problem. The forecast for how much quarrying ore remains in the current main level looks bleak. It can end in 2035.
Fredrik Björkenwall believes that technology development will be the solution, that the way LKAB finds and mines the ore will change and provide great benefits in the future. Gunnar Selberg does not dare to take a chance and believes that the space industry, tourism and other mineral resources in the municipality can replace the job if LKAB fails to secure the mine's survival.
- There's an end to a mine. I hope it doesn't happen in 2035, but in my head I work on the assumption that it might close in 15 years. We can't sit and run our heads in the sand and hope they find more ore. We must have a plan B.
Anders Elenius is more skeptical. A Kiruna without mining and LKAB? He laughs and says:
- Then you just have to fill in the pit again.

The ore will come out
A few days after the quake, Jonny Kumpula stands at his cabin in Saittarova, which is twelve kilometers outside Kiruna. A Luleå hockey flag flutters loudly in the yard and he pats one of his dogs.
Few may have heard of Saittarova, but some more may have seen Kumpula's dog. Her name is Aito and she is an actor. The Finnish lap dog played the leash puppy in the TV series "Rebecka Martinsson", which is based on the author and Kiruna daughter Åsa Larsson's crime novels.
"She's probably the biggest celebrity here anyway," he says.
Is he scared of the quake? No. Does he trust security? Yes, there is not much to it. Possibly, outsiders, loved ones, have become more aware of the environment he works in, that there are always risks. After the week off, just re-stamp. The ore is going forward.
- You either love the mountain or you hate it. You can't go down and think it's half fun.
The planned blasts in the mine always occur sometime between half past one and half at night, every day, all year round. The fact that the low hum has not been heard in a few days is very unusual. But the night towards Thursday, May 21st shakes it in the ground and windows.
It's a safe sound. The heart of the mine, the city and the municipality has begun to strike again.
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M5.6 in New Zealand, the biggest quake in the last 30 days and witnesses report it was strong but no damage. There was another last month at M5.1. Both were apparently deep enough to be near the subduction zone, the area where tectonic plates move above and below one another:
  1. Search Results
    4 of 422 earthquakes in map area.Click for more information
    1. 5.629km WNW of Foxton, New Zealand
      2020-05-24 19:53:32 (UTC)
      51.9 km
    2. 4.546km NNE of Castlepoint, New Zealand
      2020-05-14 08:54:45 (UTC)
      35.2 km
    3. 5.155km NNW of Te Anau, New Zealand
      2020-04-26 22:52:11 (UTC)
      80.0 km
    4. 4.5South of the Kermadec Islands
      2020-04-25 23:36:23 (UTC)
      https://twitter.com/x/status/1264649243140059136
      https://twitter.com/x/status/1264650032969478144
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5.4-magnitude quake hits Port Vila of Vanuatu: USGS
2020-05-27
NEW YORK, May 26 (Xinhua) -- An earthquake with a magnitude of 5.4 jolted 94 km NW of Port Vila, Vanuatu at 22:52:13 GMT on Tuesday, the U.S. Geological Survey said.

The epicenter, with a depth of 13.86 km, was initially determined to be at 17.0244 degrees south latitude and 167.8209 degrees east longitude.
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