Aftershocks, reservoirs and volcanoes: Damaging earthquakes in February 2021

Published: 03/01/2021

Although only two months have passed, the earthquake damage numbers of 2021 have almost reached those of the entire previous year. A brief overview.

Although only two months have passed, the earthquake damage numbers of 2021 have almost reached those of the entire previous year. The main reason: The earthquake on the Indonesian island of Sulawesi (Mw6.2) in January with over 100 fatalities and tens of thousands of damaged buildings. There was no such catastrophe in February. However, this month also resulted in several major earthquakes and several deaths. A brief overview:

19 damaging earthquakes were registered worldwide in February 2021, 15 fewer than in the previous month. The countries of Guinea, Armenia, Mexico, Philippines, Turkey, Chile, USA, India, Pakistan, Kazakhstan, Japan, Greece, Iran, Algeria, Iceland and Indonesia were affected by these earthquakes. In total: 3 fatalities, 341 injured and around 12,600 damaged buildings.

Table 1: Most destructive earthquakes in February 2021
Date Epicenter Mw Impact Value Fatalities Injuries Damaged buildings
February 22nd Isfahan, Iran 5.6 2.11 0 67 4000+
February 13th Fukushima, Japan 7.1 1.97 1 186 4600+
February 13th Ararat, Armenia 5.1 1.51 0 27 3000+
February 26th Maluku Utara, Indonesia 5.1 1.05 0 10 654
February 24rd Isfahan, Iran 4.5 0.96 0 30 50
February 7th Davao del Sur, Philippines 6.1 0.7 0 15 26
February 5th Gegharkunik, Armenia 5.1 0.65 0 0 279
February 12th Gorno-Badakhshan, Tajikistan 5.9 0.65 1 6 100+
February 3rd Kindia, Guinea 5.0 0.61 0 0 100+
February 3rd Sulawesi Barat, Indonesia 5.2 0.44 1 0 100+

Probably the most noticed damaging earthquake (and the strongest damaging one in this month) occurred on February 13th off the coast of the Japanese prefecture of Fukushima (Mw7.1). An aftershock of the infamous Tohoku earthquake in 2011. It was an earthquake with an unusually high Intensity. The Japanese Meteorological Authority (JMA) registered Intensity 6+ near the epicentre which is the second highest value on the Shindo scale, equal to Modified Mercalli Intensity (MM) IX - X. The measured values at some places got close to the threshold for Shindo 7, which is equal to MM X or higher.

Compared to other earthquakes with such a high intensity and a similar population density near the epicentre, the effects of this quake were relatively minor. The Fire and Disaster Management Agency (FDMA) reported 4600 damaged buildings in the days after the quake. For several days, the number of victims stood 186 injured people. But 12 days later the only fatality of this quake was found: a man living alone who was killed by a falling cabinet.

Globally however, this quake was only the fourth most damaging event in 2021.

In February, only the Sisakht quake in the Iranian province of Isfahan on the 17th had an even higher impact. With a magnitude of 5.6, it was weaker and did not claim any fatalities. However, the quake destroyed more than 800 buildings, causing over 3000 people to lose their homes. Additionally, 67 people were injured, 30 others during an aftershock a few days later.

Both Japan and Iran are among those countries which are frequently affected by damaging quakes. Guinea in West Africa is not. Nevertheless, it also appears in the damage list for February. With a magnitude of 5.0 in the Kindia province, it became the country’s most destructive event in decades. However, on a global scale the impact can be considered as “mild”: Several hundred buildings were damaged without any casualties. Numerous residents of the surrounding villages had to be evacuated. Since there has been a series of earthquakes in the same region since November, which correlates in time with the damming of a new reservoir, this earthquake is considered to be likely induced by this reservoir, although no final evidence can be given by at the moment.

Armenia also experienced its most destructive earthquake for years. An earthquake with a magnitude of 5.0 occurred near the capital Yerevan on February 13th. More than 3,000 buildings were damaged and at least 27 people were injured. A few days earlier on February 5th, a similarly strong earthquake hit the Gekharkunik region in the east of the country. Since this area is much less populated, only 279 buildings were damaged. In the small, remote villages, however, many people had to leave their homes due to the damages.

Not the most destructive but the most active earthquake sequence for decades hit the south-western parts of Iceland in the end of the month. This sequence started on February 24 with a magnitude 5.7 quake near the capital Reykjavik resulting in minor damage to a couple of homes as well as landslides and broken water pipes. The series with thousands of small to moderate tremors is still ongoing. Authorities issued a warning of possible further strong earthquakes, which lead to the evacuation of some public facilities near the epicenter. In addition, a chance for a relation to previously detected magmatic activity and therefore a possible volcanic eruption is given. The aviation alert level of the Krysuvik volcano was set to "yellow" although there is no evidence of imminent volcanic activity.

All details about damaging earthquakes can be found here: Earthquake Impact Database 2021

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Although only two months have passed, the earthquake damage numbers of 2021 have almost reached those of the entire previous year. A brief overview.