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Category Archives: Recent Global Seismic Events

2021-03-04, M7.9, Kermadec Islands

At 19:28 on 2021-03-04 a magnitude 7.9 earthquake occurred in the Kermadec Islands region. This follows two other strong events in the region today, an M7.3 event which occurred further South close to the North Island of New Zealand (see here) and an M7.4 event that also occurred in the Kermadec Islands region (see here).

New Zealands National Emergency Management Agency (NEMA) have issued a statement advising people on the east coast of the north island to move to higher ground. The earthquake had a depth of 10 km, shallow earthquakes like this present a tsunami threat.

The event was recorded by seismic stations worldwide, including stations in the Irish Nation Seismic Network (INSN) (see figure below).

The earthquake occurred along the eastern margin of the Australia plate where it meets the Pacific plate. The convergence of the two plates means the region is prone to large events such as this (there have been 15 earthquakes with magnitude greater than 7.5 since 1900).

For more information see the following:

https://earthquake.usgs.gov/earthquakes/eventpage/us7000dflf/executive

https://www.emsc-csem.org/Earthquake/earthquake.php?id=955088

https://www.civildefence.govt.nz/

2021-03-04, M7.3, New Zealand

At 13:27 on 3th March an 2021 a magnitude 7.3 earthquake occurred off the East coast of the New Zealand’s Northern Island (see map below). The Pacific Tsunami Warning Center (PTWC) immediately issued a warning for the possibility of hazardous Tsunami waves within 300 km of the earthquake epicenter along the New Zealand coast. Tsunami waves of 0.28 m were then observed on the Northeastern Cape and waves of 0.3 to 3 m have been forecast.

The event was recorded by seismic stations worldwide. The stations in the Irish Nation Seismic Network (INSN), recorded it approximately 20 minutes after it occurred (see figure below).

New Zealand is on the Eastern margin of the Australian plate and the region is prone to large events such as this (there have been 15 earthquakes with magnitude greater than 7.5 since 1900). The convergence of the Australia and Pacific plates make it one of the most seismically active areas in the world.

For more information see the following:

https://earthquake.usgs.gov/earthquakes/eventpage/us7000dffl/executive

https://www.geonet.org.nz/earthquake/2021p169083

https://www.emsc-csem.org/Earthquake/earthquake.php?id=954885


2021-02-24, M5.7, Iceland

The Reykjanes Peninsula in Iceland has suffered a series of earthquakes in the past few hours. This phenomena is known as an earthquake swarm. At the time of writing, there have been 725 quakes in the last 48 hours. The largest of which was a magnitude 5.7 that occurred at 10:05:57 on the 24th February 2021. This event was recorded by the Irish National Seismic Network and can be seen in the waveforms plotted below.

Waveforms from the magnitude 5.7 Icelandic event recorded on the 6 INSN instruments.

More information is available from the Icelandic Met Office:

https://en.vedur.is/about-imo/news/earthquake-swarm-in-reykjanes-peninsula

and on this webpage:

https://www.ruv.is/frett/2021/02/24/earthquake-alert-level-increased

present earthquake activity on the Reykjanes peninsula is shown here:

https://en.vedur.is/earthquakes-and-volcanism/earthquakes/reykjanespeninsula#view=map

2021-02-10, M7.7, Loyalty Islands

At 13:20:00 (UTC) on the 10th February 2021, a magnitude 7.7 earthquake occurred southeast of the Loyalty Islands in the Pacific, see map below. The epicenter lies in a very remote region and only few people felt the event. The earthquake struck at a depth of 10 km and according to the Pacific Tsunami Warning Center a tsunami was triggered. Reported wave heights are 78cm in Vanuatu, 47cm at Norfolk Island, 29cm in New Caledonia and 22cm at the North Cape in New Zealand. At time of writing no fatalities or building damage were reported. The Loyalty Islands region is seismically very active, 15 other earthquakes with magnitudes larger than 7 were detected over the preceding century. This seismic activity is related to the plate boundary between the Australian and the Pacific plate.

The earthquake was recorded at seismic stations worldwide, including stations of the Irish Nation Seismic Network (INSN), see seismic waveforms below.

Further information is available from the following sources:

https://www.emsc-csem.org/Earthquake/earthquake.php?id=947612

https://earthquake.usgs.gov/earthquakes/eventpage/us6000dg77

2020-12-29, M6.4, Croatia

At 11:19:54 (UTC) on the 29th of December 2020, a magnitude 6.4 earthquake occurred in Croatia about 50km SE of the capital Zagreb, see map below. The earthquake nucleated at a relatively shallow depth of 10km within the Eurasia plate. It occurred after a magnitude 5.2 earthquake struck in the same area on the 28th December 2020 at 05:28 (UTC). At the time of writing at least one fatality was reported, at least 20 injured people and building damage especially in Petrinja, a town with about 25,000 inhabitants. Though earthquakes with magnitude over 6 happened before in Croatia this is the strongest event that was ever recorded in Croatia since modern seismic instrumentation is in use. 

The earthquake was recorded at seismic stations worldwide, including stations of the Irish National Seismic Network (INSN), see seismic waveforms below.

Further information is available from the following sources:

https://www.emsc.eu/Earthquake/earthquake.php?id=933701

https://earthquake.usgs.gov/earthquakes/eventpage/us6000d3zh

2020-10-30, M7.0, Greece

At 11:51:26 (UTC) on the 30th of October 2020, a magnitude 7.0 earthquake occurred 14 km NE of Néon Karlovásion, Greece (see map below). Early reports state that there has been building collapse and a sea surge that flooded streets in the Turkish resort city of Izmir. The Mediterranean region is prone to such events due to the northward convergence of the African plate with respect to the Eurasian plate along a complex plate boundary.

The earthquake was recorded at seismic stations worldwide, including stations of the Irish Nation Seismic Network (INSN), see seismic waveforms below.

Further information is available from the following sources:

https://earthquake.usgs.gov/earthquakes/eventpage/us7000c7y0/executive

https://www.emsc-csem.org/Earthquake/earthquake.php?id=915787


2020-10-19, M7.5, Alaska

At 20:54:40 (UTC) on the 19th of October 2020, a magnitude 7.5 earthquake occurred near the Alaska Peninsula (see map below). The earthquake struck approximately 90 km south of the peninsula at a depth of 40 km. Initially a tsunami threat warning was issued by the Pacific Tsunami Warning Center, however it is now thought this threat has passed. The Alaska Peninsula is prone to large earthquakes due to the subduction of the Pacific plate beneath the North American plate in that region.

Location of the M7.5 Alaska earthquake.

The earthquake was recorded at seismic stations worldwide, including stations of the Irish Nation Seismic Network (INSN), see seismic waveforms below.

Seismic waveforms recorded by the INSN (click to enlarge).

Further information is available from the following sources:

https://earthquake.usgs.gov/earthquakes/eventpage/us6000c9hg/executive?utm_medium=email&utm_source=ENS&utm_campaign=realtime

https://www.emsc-csem.org/Earthquake/earthquake.php?id=912660

2020-07-22, M7.8, Alaska Peninsula

At 06:12:44 (UTC) on the 22nd of July 2020, a magnitude 7.8 earthquake occurred  near the Alaska Peninsula (see map below). The earthquake struck approximately 100 km south of the peninsula at a depth of 30 km. Shortly after, a tsunami warning was issued by the U.S. Tsunami Warning System. Several aftershocks of magnitude 5 and greater occurred within the hours following the main shock. Large earthquakes are common in this region due to the subduction of the Pacific plate beneath the North American plate. Since 1900, twelve earthquakes with magnitudes greater than 7.5 have occurred in this region, including the 1964 M9.2 Prince William Sound earthquake, the second largest recorded earthquake in the era of modern instrumental seismology.

The earthquake was recorded at seismic stations worldwide, including stations of the Irish Nation Seismic Network (INSN), see seismic waveforms below (select figure to enlarge).

Further information is available from the following sources:

https://www.emsc-csem.org/Earthquake/earthquake.php?id=878808

https://earthquake.usgs.gov/earthquakes/eventpage/us7000asvb/executive

2020-06-23, M7.4, Oaxaca, Mexico

At 15:29:05 (Universal Time) on the 23rd of June 2020, an earthquake of magnitude 7.4 struck in the Oaxaca region of Mexico (see map below). The earthquake occurred at a depth of 10 km, locating approximately 12 km SSW of Santa Maria Zapotitlan, Mexico. Shortly after, the Pacific Tsunami Warning Canter (PTWC) issued a warning that hazardous tsunami waves  reaching 1 to 3 m above the tide level along the coast of Mexico are possible.

Mexico is one the earths most seismically active regions due to the relative motions of three large tectonic plates (the Pacific Plate, the Cocos Plate and the North American Plate) in the region. The relatively dense oceanic crust of the pacific plate is subducting beneath the Mexican landmass. This motion can result in large earthquakes such as today’s event. The interaction of the subducting plate and the mantel rock beneath the Mexican landmass also results in volcanism in the area.

The earthquake was recorded at seismic stations worldwide, including stations of the Irish Nation Seismic Network (INSN), see seismic waveforms below (select figure to enlarge).

Further information is available from the following sources:

https://earthquake.usgs.gov/earthquakes/eventpage/us6000ah9t/executive?utm_medium=email&utm_source=ENS&utm_campaign=realtime

https://www.emsc-csem.org/Earthquake/earthquake.php?id=870434

 

2020-06-18, M7.4, Kermadec Islands

At 12:49:53 on the 18th of June 2020, an earthquake of magnitude 7.4 struck in the Kermadec Islands region of the South Pacific (see map below). The earthquake occurred at a depth of 8 km, locating approximately 650 km northeast of New Zealand’s North Island. This region of the Tonga-Kermadec subduction zone experiences high levels of seismic activity, with nearly 20 events of M 6.5+ over the past half century within 250 km the 18th of June earthquake.

The earthquake was recorded at seismic stations worldwide, including stations of the Irish National Seismic Network (INSN), see seismic waveforms below (select figure to enlarge).

Further information is available from the following sources:

https://www.emsc-csem.org/Earthquake/earthquake.php?id=868826

https://earthquake.usgs.gov/earthquakes/eventpage/us6000ae4n/executive

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