Monday, January 4, 2021

6.4 Croatia Earthquake Aftershocks Migrating North Toward Zagreb


2020 M6.4 Croatia earthquake aftershocks migrating north toward capital Zagreb, liquefaction, sinkholes reported



Aftershocks related to the M6.4 earthquake that struck the city of Petrinja, Croatia at 11:19 UTC on Tuesday, December 29, 2020, are migrating north toward the capital Zagreb, Croatia. This is the strongest earthquake to hit Croatia since records began in 1880 -- with The Great Zagreb Earthquake (M6.3) on November 9, 1880.

"The quakes are migrating onto a mapped fault that cuts through the capital city of Zagreb," Temblor seismologists said on January 1, 2021. 

"The mainshock most likely struck on an unmapped ‘right-lateral’ fault, which connects to the mapped ‘left-lateral’ fault. While unlikely, delayed triggering of another large shock is possible."

EMSC located hundreds of aftershocks with more than 165 felt in 73 hours to 11:03 UTC on January 2.

Zagreb has still not recovered from widespread damage caused by earthquakes related to M5.3 (M5.4) on March 22, 2020.

Thousands of homes and buildings have been damaged, with many not suitable for living. This means thousands of people are still living in temporary accommodation.

The map below shows all earthquakes detected since March 1, 2020, including several very damaging M5+ quakes on March 22.

Earthquakes in Croatia from March 1, 2020 - January 2, 2021. Data source: EMSC. Image credit: TW, Google

M6.4 is the largest earthquake to occur in Croatia since records began in 1880.

 At least 7 people have been killed and 28 injured, of which 6 critically.

The quake damaged or destroyed hundreds of homes and buildings in the cities of Petrinja and Sisak as well as in nearby towns and villages.

According to the USGS, liquefaction triggered by this earthquake is estimated to be significant in severity and (or) spatial extent. The number of people living near areas that could have produced liquefaction in this earthquake is significant (10 000 - 100 000).

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