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Behavior of slow earthquakes explained by new evidence

Earth from Space
© University of Ottawa
A team of researchers at the University of Ottawa has made an important breakthrough that will help better understand the origin and behavior of slow earthquakes, a new type of earthquake discovered by scientists nearly 20 years ago.

These earthquakes produce movement so slow - a single event can last for days, even months - that they are virtually imperceptible. Less fearsome and devastating than regular earthquakes, they do not trigger seismic waves or tsunamis. They occur in regions where a tectonic plate slides underneath another one, called ''subduction zone faults'', adjacent but deeper to where regular earthquakes occur. They also behave very differently than their regular counterparts. But how? And more importantly: why?

Pascal Audet, Associate Professor in the Department of Earth and Environmental Sciences at uOttawa, along with his seismology research group (Jeremy Gosselin, Clément Estève, Morgan McLellan, Stephen G. Mosher and former uOttawa postdoctoral student Andrew J. Schaeffer), were able to find answers to these questions.
"Our work presents unprecedented evidence that these slow earthquakes are related to dynamic fluid processes at the boundary between tectonic plates," said first author and uOttawa PhD student, Jeremy Gosselin. "These slow earthquakes are quite complex, and many theoretical models of slow earthquakes require the pressure of these fluids to fluctuate during an earthquake cycle."
Using a technique similar to ultrasound imagery and recordings of earthquakes, Audet and his team were able to map the structure of the Earth where these slow earthquakes occur. By analyzing the properties of the rocks where these earthquakes happened, they were able to reach their conclusions.

Seismograph

Shallow 5.6-magnitude quake hits off Amatignak Island, Alaska - USGS

Earthquake seismograph
A 5.6-magnitude earthquake jolted 65 km SW of Amatignak Island, Alaska at 0631 GMT on Sunday, the U.S. Geological Survey said.

The epicenter, with a depth of 1.0 km, was initially determined to be at 50.924 degrees north latitude and 179.875 degrees west longitude.

Comment: A few days ago a shallow magnitude 6.2 earthquake struck near Adak, Alaska.


Seismograph

NEW 5.1 earthquake hits already quake-devastated E. Turkish province

Earthquake
© Reuters / Ismail Coskun
Rescuers work on collapsed buildings after an earthquake in Elazig, Turkey, January 25, 2020.
A 5.1 magnitude quake has struck Turkey's Elazig province, one day after a 6.8 tremor leveled buildings and killed at least 22 people.

The earthquake struck at around 7:30pm local time on Saturday, at a depth of 10km, the United States Geological Survey (USGC) reported. The European-Mediterranean Seismological Centre (EMSC) has put the magnitude at 4.9.

Comment: See also: Major 6.8M earthquake strikes eastern Turkey - At least 20 dead, felt as far south as Tel Aviv

Ruptly has released drone footage of the aftermath of the earthquake in the town of Gezin:


Another video shows rescue workers searching for survivors and clearing out the rubble of a collapsed building in the same town situated dozens of miles away from the most-affected Elazig:





Seismograph

Major 6.8M earthquake strikes eastern Turkey - At least 20 dead, felt as far south as Tel Aviv

earthquake turkey
© Reuters
On 23 January, a 5.4 magnitude earthquake hit the western Turkish province of Manisa with no people being injured or killed in the incident, according to provincial Governor Ahmet Deniz.

A strong 6.8 magnitude earthquake struck eastern Turkey at 17:55:10 GMT, the European Mediterranean Seismological Centre (EMSC) reported. The epicentre of the earthquake was located 210 kilometres northeast of Gaziantep and 10 kilometres north of Doganyol, Turkey at a depth of two kilometres, according to the centre.

According to the EMSC, the earthquake was felt in Iraq, Syria, Lebanon, and Israel.

Comment:

UPDATE 21:15 CET

The death toll has risen to 4, and the quake was reportedly felt in Tel-Aviv, Israel. The damage looks bad. Expect the death toll to rise.

Update: 25th Jan. 09.09 CET

Anadolu Agency reports:
At least 20 people were killed and more than 1,015 injured Friday after a deadly earthquake rattled eastern Turkey, according to authorities.

The 6.8-magnitude quake hit eastern Elazig province at 8.55 p.m. local time, with its epicenter in Sivrice district, along with neighboring provinces and countries including Syria and Georgia.

The Disaster and Emergency Management Presidency (AFAD) said 922 others were injured; 560 in Elazig, 226 in Malatya, 37 in Kahramanmaras, 34 in Sanliurfa, 34 in Diyarbakir, 25 in Adiyaman, 6 in Batman.

Health Minister Fahrettin Koca announced the updated death toll, saying: "We have approximately 30 residents under the wreckage in Elazig."

The search and rescue operations are continuing and the death toll could rise, said Koca.

Update 26 Jan 15:00 CET

24 hours later, a mother and her baby have been rescued from the rubble in Elaziq:





Seismograph

Shallow M3 earthquake shakes homes of Teeside, UK

stockton-on-tees
Teesside has been struck by an earthquake of 3.0 magnitude which woke people up and caused homes to shake.

The tremor was felt across Stockton, Billingham, Hartlepool, Wolviston and Middlesbrough just before 06:00 GMT.

People posted on social media to say they heard a rumbling or felt their houses shake. Emergency services said they received calls but there were no reports of damage.

The website Earthquake Track said it was six miles (10km) beneath Stockton.

Comment: Despite the geologist claiming that this is fairly normal because the UK sees these kinds of quakes "three times a year", there have in fact been a significant number more - below are just some recorded in the last year:


Seismograph

Shallow magnitude 6.2 earthquake strikes near Adak, Alaska - USGS

The location of a magnitude 6.2 earthquake Wednesday night in Alaska’s Aleutian Islands
© Los Angeles Times
The location of a magnitude 6.2 earthquake Wednesday night in Alaska’s Aleutian Islands.
An earthquake with a reviewed magnitude of 6.2 shook west of city of Adak in Alaska on Thursday, according to the US Geological Survey.

The earthquake was recorded at 5:53 a.m. UTC. The quake's epicentre was located 22 kilometres east of the Tanaga volcano, which is part of the Aleutian Islands system. The epicentre lay at a depth of 10 kilometres.

No information was received regarding casualties and destruction. The tsunami threat was not announced.


Seismograph

Shallow 6.4 earthquake kills one, injures others in China's Xinjiang region

Rescuers check for safety hazards in Jiashi County in Kashgar Prefecture, Xinjiang Uygur Autonomous Region, on Monday.

Rescuers check for safety hazards in Jiashi County in Kashgar Prefecture, Xinjiang Uygur Autonomous Region, on Monday.
A 6.4-magnitude earthquake has killed one person and slightly injured two others in northwest China's Xinjiang Uygur Autonomous Region, authorities said on Monday.

Authorities have recorded 10 aftershocks above the magnitude of 3, with the highest at 5.2, according to the regional publicity department.

The quake jolted Jiashi County in Kashgar Prefecture in the province's southwest at 9:27pm on Sunday, according to the China Earthquake Networks Center.

The epicenter was monitored at 39.83 degrees north latitude and 77.21 degrees east longitude. The quake struck at a depth of 16 kilometers, the center said in a statement.

The tremor toppled four private stores and 1,084 meters of walls, and caused cracks in more than 1,000 houses and 5,574 meters of walls.


Seismograph

Magnitude 6.2 earthquake hits the South Sandwich Islands

south sandwich
Most important Earthquake Data:

Magnitude : 6.2

Local Time (conversion only below land) : Unknown

GMT/UTC Time : 2020-01-20 06:51:29

Depth (Hypocenter) : 94 km

Seismograph

Shallow M6.0 earthquake hits Papua, Indonesia

Earthquake seismograph
A strong 6.0 magnitude earthquake shook Indonesia's easternmost region of Papua on Sunday, the United States Geological Survey said.

There was no tsunami warning accompanying the quake which struck inland 158 kilometres (98 miles) from the provincial capital Jayapura at a shallow depth of almost 34 kilometers, USGS said.

The Southeast Asian archipelago is one of the most disaster-prone nations on Earth.

In 2018, a 7.5-magnitude quake and a subsequent tsunami in Palu on Sulawesi island left more than 4,300 people dead or missing.

Seismograph

ANOTHER quake shakes Puerto Rico - 5.9m

Puerto rico earthquake January 2020
© USGS
ShakeMap of the 5.9 magnitude earthquake that struck southwest Puerto Rico on Jan. 11, 2020.
The latest in a series of earthquakes and aftershocks struck off the southwest coast of Puerto Rico just before 9:00 a.m. on Saturday morning.

The center of the 5.9 earthquake is located about 8 miles south of Guanica, Puerto Rico, as reported by the United States Geological Survey (USGS).

There is no threat for a tsunami at this time.