2000 Iceland earthquakes

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2000 Iceland earthquakes
Iceland relief map.jpg
Bullseye1.png
UTC  time2000-06-17 15:40:41
 2000-06-21 00:51:46
ISC  event 1736604
  1736730
USGS-ANSS ComCat
  ComCat
Local date17 July 2000
 21 July 2000
Local time15:40 GMT (UTC+0)
 00:51 GMT (UTC+0)
Magnitude6.5 Mwc [1]
 6.5 Mwc [2]
Depth10 km (6.2 mi)
Epicenter 63°58′48″N20°45′29″W / 63.980°N 20.758°W / 63.980; -20.758
FaultÁrnes Fault
Hestfjall Fault
Areas affected Southern Region, Iceland
Total damageUS$20 million ($36.6 million in 2024, adjusted for inflation)
Max. intensity MMI IX (Violent)
Peak acceleration0.85 g
CasualtiesSeveral injured

Two earthquakes, both measuring Mw 6.5, struck southern Iceland near the town of Selfoss on 17 and 21 June 2000. [1] [2] There were no fatalities but were multiple minor injuries and considerable damage to infrastructure. [3] The two earthquakes were the first major seismic activity in Iceland for 88 years. [4]

Contents

Tectonic setting

Iceland lies on the spreading axis of the Mid-Atlantic Ridge (MAR) where it is influenced by the Iceland hotspot, a major mantle upwelling. The active spreading axis of the MAR is moving westward with respect to the hotspot. This means that the active rifts above the hotspot have progressively jumped towards the east, causing the development of two major transform zones in the north and south of the island. To the south the zone is the South Iceland Seismic Zone (SISZ), which has a west–east trend and is about 20 km wide. Most earthquakes in this zone are associated with movement on north–south trending right lateral strike-slip faults, although there is also evidence of WSW–ENE trending faults. [5]

According to historical records, there have been 33 damaging earthquakes in the SISZ from the 11th century up to June 2000, with the latest being in 1896 and 1912. [5]

Earthquakes

The first of the earthquakes occurred at 15:40 UTC on 17 June at a depth of 6.3 km. The magnitude estimated by the Icelandic Meteorological Office was 6.4 Mw , assuming a single fault, although such a model did not fit all the available data. The extent of aftershocks defined a 16 km long north–south fault rupture, continuing down to 10 km. The causative fault was the Árnes Fault and a large number of surface fissures were mapped along this structure in the days following the event. [5] It also had a peak ground acceleration of 0.64 g. [3]

The second earthquake occurred at 00:51 UTC on 21 June at a depth of 5.1 km. The extent of aftershocks defined an 18 km fault rupture down to 8 km depth. The causative fault was the Hestfjall Fault. Surface fissures were developed over a distance of about 25 km. [5] A peak ground acceleration of 0.85 g was calculated for the second quake, based on damage to a bridge crossing the Þjórsá river. [3]

Impact

Severe damage from both quakes occurred to a combined area of about 800 km2 (310 sq mi), stretching from Landssveit and Holta to Rangárvellir. Most of the affected buildings were of poor quality, being built on unstable foundations. The greatest damage occurred to farms, summer cottages and utility and communication systems. Six Landsvirkjun high-voltage masts were affected in the earthquakes when guy-wires and foundations subsided by up to 30 cm (0.98 ft), with repairs lasting until 22 June. [3]

The first earthquake resulted in one injury and the closure of some roads at Vestmannaeyjar. In Hella, 11 houses were destroyed, 19 others and a glass factory were damaged and utilities were disrupted. Overall, the first earthquake resulted in US$20 million worth of damage. [6] The second earthquake caused several minor injuries, [3] destroyed 12 homes and severely damaged 24 others in the Grímsnes region, and damaged water pipes in the Selfoss-Eyrarbakki-Stokkseyri area. [7]

See also

Related Research Articles

<span class="mw-page-title-main">Lists of earthquakes</span>

Earthquakes are caused by movements within the Earth's crust and uppermost mantle. They range from weak events detectable only by seismometers, to sudden and violent events lasting many minutes which have caused some of the greatest disasters in human history. Below, earthquakes are listed by period, region or country, year, magnitude, cost, fatalities, and number of scientific studies.

The 1965 Puget Sound earthquake occurred at 08:28 AM PDT on April 29 within the Puget Sound region of Washington state. It had a magnitude of 6.7 on the moment magnitude scale and a maximum perceived intensity of VIII (Severe) on the Mercalli intensity scale. It caused the deaths of seven people and about $12.5–28 million in damage. There were no recorded aftershocks.

The 1935 Helena earthquake occurred at 22:48:02 MDT on October 18 in Montana, with an epicenter near Helena. It had a magnitude of 6.2 on the surface-wave magnitude scale and a maximum perceived intensity of VIII (Severe) on the Mercalli intensity scale. The temblor on that date was the largest of a series of earthquakes that also included a large aftershock on October 31 of magnitude 6.0 and a maximum intensity of VIII. Two people died in the mainshock and two others died as a result of the October 31 aftershock. Property damage was over $4 million.

On 4 May 2000 at 12:21 WITA, a Mw7.5 earthquake struck off the coast of Banggai Islands Regency, Central Sulawesi, Indonesia, which was followed by a damaging local tsunami. The earthquake and tsunami killed at least 54 people and injured 270 others, with most of the damage and casualties occurring in the Banggai Islands.

The western coast of West Sulawesi was struck by a major earthquake on 23 February 1969 at 00:36 UTC. It had a magnitude of 7.0 Mw and a maximum felt intensity of VIII on the Modified Mercalli intensity scale. It triggered a major tsunami that caused significant damage along the coast of the Makassar Strait. At least 64 people were killed, with possibly a further 600 deaths caused by the tsunami.

During April 1819, the area around Copiapó in northern Chile was struck by a sequence of earthquakes over a period of several days. The largest of these earthquakes occurred on 11 April at about 15:00 local time, with an estimated magnitude of Mw 8.5. The other two events, on 3 April between 08:00 and 09:00 local time and on 4 April at 16:00 local time, are interpreted as foreshocks to the mainshock on 11 April. The mainshock triggered a tsunami that affected 800 km of coastline and was also recorded at Hawaii. The city of Copiapó was devastated.

The northern part of the Ottoman Empire was struck by a major earthquake on 13 August 1822. It had an estimated magnitude of 7.0 Ms and a maximum felt intensity of IX (Destructive) on the European macroseismic scale (EMS). It may have triggered a tsunami, affecting nearby coasts. Damaging aftershocks continued for more than two years, with the most destructive being on 5 September 1822. The earthquake was felt over a large area including Rhodes, Cyprus and Gaza. The total death toll reported for this whole earthquake sequence ranges between 30,000 and 60,000, although 20,000 is regarded as a more likely number.

The 2003 Dayao earthquake occurred on July 21, at 23:16:33 CST. The epicenter of the moment magnitude 5.9 earthquake was in Dayao County in the mountainous area of central Yunnan, China. At least 19 people were killed, 644 were injured, and 8,406 families became homeless. The quake also caused $75 million USD in damage.

<span class="mw-page-title-main">1641 Tabriz earthquake</span> Earthquake centered in northwestern Iran

The 1641 Tabriz earthquake occurred on the night of 5 February in present-day East Azerbaijan province, Iran. The earthquake had an estimated surface-wave magnitude of 6.8 and an epicenter between Lake Urmia and the city of Tabriz. It was one of the most destructive earthquakes in the region, resulting in the loss of up to 30,000 lives.

The 1979 Yapen earthquake occurred on September 12 at 05:17:51 UTC. It had an epicenter near the coast of Yapen Island in Irian Jaya, Indonesia. Measuring 7.5 on the moment magnitude scale and having a depth of 20 km (12 mi), it caused severe damage on the island. At least 115 were killed due to shaking and a moderate tsunami.

<span class="mw-page-title-main">1917 San Salvador earthquake</span> 1917 earthquake in Central America

The 1917 San Salvador earthquake occurred on June 7 at 18:55 local time near the Salvadoran capital. The hypocenter of the Mw  6.7 was at a shallow depth of 15 km (9.3 mi), and occurred along a shallow crustal fault near San Salvador. The earthquake caused significant destruction of the city and left approximately 1,050 dead. It was followed by an eruption on San Salvador that killed another 1,100. Only behind the earthquake of 1986, it is the second deadliest in El Salvador's history.

The 1980 Livermore earthquake occurred on January 24 at 11:00 PST in California. The epicenter of the 5.8 Mw earthquake was a hilly area 12 km (7.5 mi) southeast of Mount Diablo and north of Livermore Valley. The earthquake had a maximum Modified Mercalli intensity of VII. Forty four people were injured and damage across the San Francisco Bay Area totaled $11.5 million, with the majority inflicted at the Lawrence Livermore National Laboratory.

On November 14, 1986, a strong earthquake with a recorded magnitude of 7.4 struck Hualien City in Taiwan. The earthquake killed 15 people and injured 44. Landslides occurred along a highway between Su'ao and Hualien. The Taiwan–Guam and Taiwan–Okinawa undersea telecommunication cables were damaged. The earthquake triggered a tsunami with a maximum height of 0.3 m. The tsunami sank 10 fishing boats in Hualien and Yilan and was attributed to six injuries.

References

  1. 1 2 ANSS. "M 6.5 - 25 km E of Selfoss, Iceland 2000". Comprehensive Catalog. U.S. Geological Survey.
  2. 1 2 ANSS. "M 6.5 - 12 km ENE of Selfoss, Iceland 2000". Comprehensive Catalog. U.S. Geological Survey.
  3. 1 2 3 4 5 Sigbjörnsson, Ragnar (2007). "South Iceland Earthquakes 2000: Damage and Strong-Motion Recordings". University of Iceland Earthquake Engineering Research Centre. Archived from the original on 14 July 2007. Retrieved 5 January 2025.
  4. ↑ Ragnar Stefánsson; Gunnar B. Guðmundsson. "The two large earthquakes in the South Iceland seismic zone on June 17 and 21, 2000". Archived from the original on 25 July 2001. Retrieved 25 July 2001.
  5. 1 2 3 4 Bergerat, F.; Angelier, J. (2003). "Mechanical behaviour of the Árnes and Hestfjall Faults of the June 2000 earthquakes in Southern Iceland: inferences from surface traces and tectonic model". Journal of Structural Geology. 25 (9): 1507–1523. Bibcode:2003JSG....25.1507B. doi:10.1016/S0191-8141(02)00168-2.
  6. ↑ NOAA (1972). "National Geophysical Data Center / World Data Service (NGDC/WDS): NCEI/WDS Global Significant Earthquake Database". NOAA National Centers for Environmental Information. doi:10.7289/V5TD9V7K . Retrieved 5 January 2025.
  7. ↑ NOAA (1972). "National Geophysical Data Center / World Data Service (NGDC/WDS): NCEI/WDS Global Significant Earthquake Database". NOAA National Centers for Environmental Information. doi:10.7289/V5TD9V7K . Retrieved 5 January 2025.
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