Earthquake Review 2020

Published: 01/28/2021


Contrary to many other years of the 21st century, no earthquake has left a global scale footprint in 2020. But 2020 was dominated by smaller destructive earthquakes with only local impact. This leaves 2020 as one of least active years in terms of earthquake damage for years.

Introduction

Although earthquakes are one of the most common natural phenomena, they are considered as one of the scariest and most dangerous by many people. Given their unpredictable nature, their potential disastrous impact and their influence in the history of many cultures and nations, earthquakes are often associated with destroyed buildings and life-threatening conditions. Several databases have collected detailed information about the impact of recent and historic earthquakes, allowing a rather detailed overview of earthquake losses in many regions, sometimes with recordings of several thousand years. However, most databases only focus on the largest and most destructive earthquakes. Therefore, a lack of knowledge regarding the impact of smaller quakes is present.

In 2013, the Earthquake Impact Database (EID) was introduced with the target to create the most complete collection of damaging earthquakes. Any kind of damage to human-made buildings is set as the lower threshold. Therefore, even small quakes with minor impacts like cracked walls or damaged bricks fit the criteria of Earthquake Impact Database. More than 2200 damaging events were detected between 2013 and 2019. 2020 however became the year with the lowest number of Earthquake Impact Database events.

Currently the Earthquake Impact Database is a project of the German Thinktank Risklayer and its affiliated web projects earthquake-report.com, CATNews and erdbebennews.de. Other more extended projects like the Risklayer Explorer , where the Earthquake Impact Databases will be integrated, are planned. However, an important aspect is to keep the database available for everyone and allow usage for any kind of purpose. Therefore, the complete databases of every year since 2013 are accessible via Google Spreadsheets.

The following text will provide a summary of the global earthquake activity in 2020 with focus on the Earthquake Impact Database statistics. Additionally, we would like to compare the year 2020 with previous years.

Methods and sources

Data Collection

Damage information and statistics for the Earthquake Impact Databases are taken from various sources. The kind of source mainly depends on the availability and on the damage degree. The preferred sources used for larger damaging events, are official statistics provided by governmental or non-governmental disaster management agencies or ministries. Countries like Indonesia (National Board for Disaster Management, BNPB ), Peru (Instituto Nacional de Defensa Civil, Indeci ) and Japan (Fire and Disaster Management Agency, FDMA ) publish detailed reports about disasters of any kind on national or sub-national administrative level and provide all necessary loss information. If no official publications are available, either because the event was too small or no Disaster Management Agency exists in the affected regions, news websites are the second preferred source. Following journalistic standards, news information are often directly taken from other official sources that are unavailable to us or unknown or provide fast and first-hand information from rescue teams.

Furthermore, Social Media has become a more important source over the past few years. Earthquake-related posts from the epicentral region, e.g. on Twitter, often give an idea about the potential earthquake impacts and sometimes even share damage reports or photos. In densely populated regions like Europe or California, these community-based reports are often the only source for damage for smaller events. However, during larger quakes that grab more international attention, a higher rate of false or misinterpreted information requires special caution and therefore limits the reliability of this source.

Loss types

Within the Earthquake Impact Database 2020, statistics for fatalities, injuries, displaced people, damaged buildings and destroyed buildings are collected. While the definition of fatalities should be self-explanatory, different criteria for some countries made it necessary to provide a clearer definition for the other values. Direct earthquake effects are counted as well as direct losses by secondary effects, such like tsunamis, landslides of any kind, snow avalanches, ground liquefaction or sinkholes.

  • Injuries: A person is counted as injured if medical treatment due to a directly earthquake-related accident is needed, as far as confirmed by the sources.
  • Displaced people: All people that were temporarily or permanently displaced due to damage to homes or other facilities.
  • Damaged building: Any kind of building that suffered structural or non-structural damage with continuous usage.
  • Destroyed building: Any kind of building that suffered structural damage and was declared as temporarily or permanently unusable.

Not included are the financial or economic losses as well as damage to infrastructure (e.g., power lines, water pipes) or any kind of furniture, vehicles, contents or any other objects of value.

Impact Value

An important aspect of the Earthquake Impact Database is the Impact Value (D) that was introduced in the 2017 version of the database. The target of the Impact Value is to allow a comparison of earthquake losses that is not dependent on the economic strength of the affected countries. Therefore, only human and building losses are used to calculate it.

D = log(1+C+I ∙ IR+H ∙ HR+Da ∙ DaR + De ∙ DeR)

with the number of fatalities (C), injuries (I), displaced people (H), damaged buildings (Da) and destroyed buildings (De) for each earthquake and the loss factors IR, HR, DaR and DeR that describe the relative frequency of each loss type in previous damaging earthquakes since 2000. The lowest possible impact value is D = 0.004 for events with only one damaged building. Although the Impact Value was originally designed for the Earthquake Impact Database, no earthquake-specific loss type is used. Therefore, an application on other kind of natural or human-made disasters is possible. Options for usage are currently under investigation and will be applied to the Natural Disaster coverage on risklayer-explorer.com.

This type of index was introduced through Blong (2003) who introduced a “New Damage Index” which expressed all damage in terms of “Housing Equivalents”, normalising out damaged and destroyed structures.

The Impact Value goes one step further by adding in the social aspects in order to give the equivalent index.

Source quality value

All damage and loss information were searched and taken manually from sources. In the case of sources in foreign languages, Google Translator is used to translate the report in our native languages. As this translation might not be perfect, especially for translations from less used languages, wrong words and interpretations might provide an error source. However, due to the translation in different target languages (mainly Spanish, English and German) we try to identify possible errors and reduce the chance of false statistics. To make the quality of the estimations and the data sources transparent, a Quality Value was introduced, following the definitions in Table 1.

Table 1: Quality factor scale used to describe the reasonability of earthquake loss data and sources in Earthquake Impact Database 2020 and its usage.
Value Definition Sources in EID 2020
1 Detailed statistics from official sources or media reports based on official sources 139
2 Reasonable media reports or official sources with rough or estimated numbers; Detailed first-hand, unofficial sources 144
3 Doubtful or unclear official/media sources or reports with unspecific data or unspecific quake information 23
4 Doubtful first-hand sources or doubtful and unrealistic data from media sources 1
5 Unconfirmed media reports with reasons to assume (intended) wrong information about quake and/or losses 1

Following these definitions, we consider events with a quality value of 5 as a highly doubtful loss event with reasons to question the source. For further statistics, these events are excluded from the database. However, as we cannot prove the falsity of this source, the event will remain with special remarks in the database. Events with a quality value of 4 are also marked with special remarks, explaining the reason for doubts, but no further exclusions from statistics are done.

2020 in a nutshell

Table 2: Strongest earthquakes in 2020 (Epicenter and Magnitude: USGS)
Date Epicenter Mw Impact Value Fatalities
July 22nd Alaska, UnitedStates 7.8 0.020 0
January 28th Caribbean Sea  7.7 0.599 0
October 19th Alaska, UnitedStates 7.6 0 0
March 25th Kuriles, Russia 7.5 0.004 0
June 23rd Oaxaca, Mexico 7.4 2.057 10
June 18th Kermadec Islands,New Zealand 7.4 0 0
October 30th Samos, Greece 7.0 3.055 118
July 17th Morobe, Papua NewGuinea 7.0 1.64 1
February 13th Kuriles, Russia 7.0 0.02 0
September 18th Central Mid AtlanticRidge 6.9 0 0

The United States Geological Survey (USGS) has detected 13,654 earthquakes of magnitude 4.0 or larger in 2020. Of them 1437 quakes were larger than Magnitude 5. Using this count, 2020 would be the year with the lowest global seismic activity since at least 2003, a year however with uncertainties regarding missing undetected events. With nine quakes of Magnitude 7, 2017 was the only year with a lower number (6) in the 21st century. Therefore 2020 can be considered as a year with average to under-average seismicity, which is also seen in the earthquake losses, although these values are usually not directly related. But more strong quakes of Magnitude 7 mean a higher chance for a high-impact event. Taking data from Impact Databases, 2020 can be seen as one of the years with the least impact. Only three events with an Impact Value of 3 or higher were registered while the number of damaging events was the second lowest in the young history of EID. Another indicator for the low impact of the year is the number of earthquake fatalities. Only two years since 1900 had a lower death toll (with data from EID and CATDAT)

Earthquakes in 2020

Damaging earthquakes in 2020
Figure 1: Annual number of earthquake fatalities and damaging earthquakes since 1900. The sudden jump of damaging quakes in 2013 is caused by a change of sources and cut-off criteria. Data from 2013 to 2020 were taken from the Earthquake Impact Database, which follows other criteria than CATDAT, which covers the years 1900 - 2012.

Like 2019, no massive earthquake disaster has happened in 2020. The largest impacts and losses were mainly caused by medium quakes between magnitude 6 and 7. The lack of large quakes with below-average magnitude 7 events and no magnitude 8 event as well as the remote location of most magnitude 7 quakes contributed to this statistic. Further, the most damaging medium events has hit densely populated areas in Southern Europe or Near East, where many buildings without earthquake resistance are still in use. However, the number of damaging earthquakes has been slightly lower than in the previous years. 286 events were noticed including which affected 59 countries. From these quakes, 208 fatalities and 3602 injuries were reported. About 200,000 buildings suffered damage and 177,000 people were displaced.

The most damaging events
Table 2: Strongest earthquakes in 2020 (Epicenter and Magnitude: USGS)
Date Epicenter Mw Impact Value Fatalities
December 29th Sisak-Moslavina,Croatia 6.4 3.333 7
January 24th Elazig, Turkey  6.8 3.188 44
October 30th Samos, Greece 7.0 3.055 118
February 23rd West Azerbaijan 5.7 2.737 10
March 22nd Zagreb, Croatia 5.3 2.602 1
January 7th Puerto Rico, UnitedStates 6.4 2.077 4
June 23rd Oaxaca, Mexico 7.4 2.057 10
January 19th Xinjiang, China 6.4 2.057 10
August 17th Bicol, Philippines 6.6 1.939 2
June 14th Turkey, Bingöl 5.8 1.869 1

The Mw6.4 Croatia quake on December 29th became the most destructive earthquake of the year with an Impact Value of 3.33 (as of January 20th). Seven people died in this quake while more than 64,000 buildings were damaged. Besides Croatia, Bosnia-Herzegovina, Slovenia and Hungary were also affected with several hundred damage reports. Minor damage was reported from parts of Austria, Germany and Italy.

Earlier in the year on March 22nd a weaker Mw5.3 hit the nearby Croatian capital Zagreb and damaged more than 20,000 buildings. One person was killed by falling debris and several others injured.

The deadliest event of the year also hit the Mediterranean area. On October 30th, the Greek island of Samos and nearby Turkish province Izmir were hit by a Mw7.0 quake, which caused a small tsunami and the collapse of several high-rise buildings in Izmir city. Although destruction was less widespread than in Croatia due to the offshore location, 118 people were killed by collapsed structures and more than 1000 injured. The Impact Value for this event is 3.05, including losses in Turkey and Greece.

Another more destructive but less deadly event hit the eastern Turkish region Elazig in January, leading to 44 fatalities and the destruction of more than 6000 buildings. Also, a Mw5.7 quake in nearby East Azerbaijan Province, Iran, had destructive effects in Turkey with 10 fatalities and more than 5000 damaged buildings. No fatalities but a similar amount of damage was caused in the epicentral area in Iran.

Figure 2: Damaging earthquakes (coloured circles) 2020 and all quakes of Magnitude 4.5 and larger (white dots).
Countries

With the destructive events in Izmir, Elazig and Van, Turkey became the country with the highest earthquake losses 2020. 31 damaging quakes nationwide led to 181 deaths and 2885 injuries while more than 54,000 buildings were damaged. The only country with a higher number of damaging quakes is Iran: 41 events of earthquake damage were counted here. Most of these quakes caused only minor losses. Three indirect, panic-related fatalities resulted from quakes in Tehran (Mw5.1) in Semnan (Mw4.3), about 6000 buildings were damaged. All these losses led to the third highest impact value of all countries behind Turkey and Croatia. Although the number of damaging earthquakes was low in Croatia (5), the two events in Zagreb (Mw5.3) and Sisak-Moslavina (Mw6.4) were among the biggest loss events of the year.

24 damaging earthquakes occurred each in India and Indonesia, although both countries were spared by massively destructive quakes. Especially Indonesia, which was severely impacted in the previous years, records a rather low loss number. One fatality and less than 2000 damaged structures are officially confirmed. Even lower is the number in India with about 600 damaged structures, but here large uncertainties have to be considered.

China, known as one of the most severely affected countries by earthquakes historically, has like Indonesia been spared in 2020. 21 damaging quakes, a record-low for China in EID, five fatalities and 3500 damaged structures are the summed losses. A Mw5.0 event in Yunnan (four fatalities) had the largest impact.

A rather high number of damaging (and strong) quakes was recorded in the United States. Mostly minor damage followed strong quakes in Idaho (Mw6.5), Utah (Mw5.7) and Nevada (Mw6.5). while moderate quakes in North Carolina (Mw5.1) and Massachusetts (Mw3.6) had a rather high impact. Most of the US losses however are related to an earthquake sequence in Puerto Rico, which began shortly after Christmas 2019 and brought several strong events in January 2020. The biggest with Mw6.4 destroyed homes and even caused a small tsunami. Four fatalities are associated with this event.

Figure 3: Cumulated Impact Value of all damaging earthquakes per country.

Greenland: A rare earthquake along the south-eastern coast of Greenland became the first damaging earthquake of the autonomous region since Earthquake Impact Database was established. This event on April 17th in the region Semersooq was part of a small sequence that was detected by the Danish Geoscience Agency GEUS . The strongest event reached Magnitude 4.0. Although most parts of Greenland are unpopulated, this event took place near the village Tasiilaq, where several houses suffered minor damage, according to GEUS. The rather low seismicity in Greenland and the extremely low population density makes damaging events unlikely.

Taal-Eruption: In early 2020, the volcano Taal on the Philippine island Luzon erupted. Following this eruption, a sequence of minor to moderate earthquakes shook the area. Many of these quakes were felt strongly with reported intensities up to MMI VI. These events had damaging impacts to several settlements around the Taal Lake. However, massive ground deformation with the formation of large surface cracks followed the magmatic activity after the initial eruption and caused additional damage. The exact number of damaged structures by each of these two processes remains unclear. In official disaster management reports from the Philippines (DROMIC, NDRRMC) they were not separated. Thus, the total loss number was taken for EID which makes it a loss event with uncertain impact.

Kashmir military area: In the last days of September, the border region of India and China (Kashmir region) was struck by several earthquakes of moderate size with M4.9 as the strongest detected magnitude. Although no damage was reported officially by any Indian site, the Chinese website “360Kuai” has repeatedly mentioned this earthquake sequence, saying that it severely affected an Indian military camp. Deadly avalanches were also mentioned. “360Kuai” can be considered as a typical tabloid journalism. Its trustworthiness is doubtful, especially due to the military conflict between China and India. However, as India usually keeps all kind of military operations secret and therefore, we have a reason to believe that such earthquake effects as described by “360Kuai” do not come to the public, we cannot completely exclude that there have been impacts. So, the earthquake sequence became the only event with a Quality Factor of 5 in the 2020 Impact Database. Its possible effects are noted but as they are highly doubtful, they were not considered in further statistics.

Alsace geothermal project: Since 2019 the French city Strasbourg, capital of Alsace region, was shaken by a sequence of induced earthquakes, following the beginning of a geothermal project north of the city. This led to a rather strong Magnitude 3.6 event in December 2020 that was felt across the Alsace and nearby areas of Germany. Due to a high number of induced earthquakes from previous geothermal projects in this area, several protest organisations formed. The high number of reported damaged structures following the December 2020 event (400 only in France) is believed to be highly overestimated with several false damage reports due to the protest movements. The intensity of this event did not exceed MMI V, basing on several hundred testimonies.

Unlocated events

Although the coverage across the globe with seismological stations has steadily improved, there are still some gaps within the networks. Quakes with magnitudes below a certain threshold remain unnoticed. If they happen in densely populated and less developed regions, they might be even strong enough to cause damage. For the EID this means there are still events without magnitude and uncertain origin. Sometimes it is not even clear whether the described event was an actual earthquake or a similar seismic event (e.g., mining blast, sinkhole or landslide). In 2020, we detected seven damaging seismic events that were not picked up by any seismological agency. Of those five happened in India. Two of them (in Karnataka on February 19th and in Rajasthan on December 13th) are considered as uncertain earthquakes due to their unknown origin while three in India and one in Sri Lanka are supposed to have a non-tectonic origin. Only a quake in Guinea on April 9th can be confirmed as an earthquake due to recordings on two seismological stations in Ghana and Mali and the known cluster of seismicity in this area in recent years.

Table 4: Unlocated damaging events and their assumed origin. For all these events, no exact damage statistics were available.
Date Epicenter Assumed origin Impact Value
February 19th Karnataka, India Unknown 0.020 7
March 3rd Kerala, India Reservoir-inducedearthquake 0.004 44
April 9th Labé, Guinea Earthquake 0.038 118
June 10th Assam, India Uncontrolled gasleak  0.038 10
August 13th Kerala, India Monsoon-triggeredearthquake 0.164 1
August 29th Kandy, Sri Lanka Reservoir-inducedearthquake 0.020 4
December 13th Rajasthan, India Unknown  0.056 10
Tsunamis in 2020

The impact of earthquake generated tsunamis in 2020 was quite low. The only damaging tsunami event followed on the Magnitude 7.0 Samos earthquake. A tsunami with a maximum amplitude of more than 3 meters hit the nearby coasts of Samos and Izmir with a maximum run-up of 6 meters in Akarca. Smaller waves travelled across the Aegean Sea and were measured by several tide stations. Damage was caused along the coast of Samos and especially along the coast of Izmir province, where several stores and residential units close to the shore were inundated. At least one person drowned there.

Table 5: Earthquake-generated tsunamis in 2020.
Date Affected Region Mw Tsunami Impact Fatalities Tsunami Height
February 19th Karnataka, India Unknown 0.020 7
March 3rd Kerala, India Reservoir-inducedearthquake 0.004 44
April 9th Labé, Guinea Earthquake 0.038 118
June 10th Assam, India Uncontrolled gasleak  0.038 10
August 13th Kerala, India Monsoon-triggeredearthquake 0.164 1
August 29th Kandy, Sri Lanka Reservoir-inducedearthquake 0.020 4
December 13th Rajasthan, India Unknown  0.056 10

Summary

No magnitude 8 events, a very low death toll and a very low impact: Contrary to many other years of the 21st century, no earthquake has left a global scale footprint in 2020. However, smaller destructive earthquakes of the class that have historically happened every few months were still present in this year. While there were some events in Eastern and South Eastern Asia, these usually active countries recorded a rather calm year. Several areas in the Mediterranean area and the Middle East were hit with localized severe impacts due to earthquakes occurring at shallow depth, high population density and low building standards. Most of the strong earthquakes however had very little damage this year.

By the absence of huge earthquake disasters 2020 led the focus on those smaller high-impact events, that threaten many parts of the world, including most parts of southern Europe, southern Asia and the western regions of America. With a widely unexpected biological disaster (coronavirus) ongoing, 2020 might bring back the awareness of possible but unlikely natural hazards, especially on those areas that are not frequently affected, given that nearly every location on Earth has been affected. In addition, it has caused logistical problems in earthquake response for the smaller events this year with increased protocols in search and rescue and the post-disaster phase, engineering checks of buildings, international aid, health facilities and availability of medical staff, all causing potential impacts to the numbers this year.

Those destructive quakes near Izmir or Zagreb were a reminder for the vulnerability of densely populated areas, and rare but damaging earthquakes in Greenland and North Carolina for those unexpected hazards. A year with low losses does not need to be that big exception that it was in the 1900s. It comes down to a certain degree to the better engineering standards, more earthquake resistant codes, better quality building materials and better law enforcement. Knowledge about the spatio-temporal distribution of disasters that EID and similar projects provide are a step in the right direction.

Final note: You can reach the Earthquake Impact Database via this Link

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