2017 Valparaiso earthquake

The Valparaíso earthquake of April 2017 was a strong earthquake that shook the cities of Valparaíso and Santiago on Monday, April 24, 2017 at 18:38 local time and 21:38 UTC. Its epicenter was located off the coast of the Valparaíso Region and had a magnitude of 6.9 Mw.[1][2][3] On the scale of Mercalli, the earthquake reached an intensity VII.[4]

2017 Chile earthquake
USGS ShakeMap of the earthquake
UTC time2017-04-24 21:38:30
ISC event610548803
USGS-ANSSComCat
Local dateApril 24, 2017 (2017-04-24)
Local time18:38 CLST (UTC-3)
Duration47 seconds approximately.
Magnitude6.9 Mw[1][2][3]
Depth28 km (USGS)[1]
Epicenter33.038°S 72.062°W / -33.038; -72.062 (earthquake)
TypeThrust
Areas affectedCentral Chile
Max. intensityVII (Very strong) [4]
TsunamiYes
ForeshocksYes; 138 in less than 2 days.
Aftershocks13 of 5.0 Mw to 5.9 and 1 of 6.0  Mw, over 1000 in total.
CasualtiesNone

Before this seismic event there was an unusual increase in seismic activity (seismic swarm) that began on Saturday, April 22 and before the event of magnitude 6.9 more than 180 earthquakes (precursor earthquakes) had been recorded, being one of the most strong that of magnitude 6.0 of the dawn of the April 22, 2017.

Subsequent to this event, more than 1000 aftershocks have been recorded, including several earthquakes of magnitude greater than 5.0 and two earthquakes of magnitude 5.8 and 6.0 on Moment magnitude scale that occurred on Friday, April 28, 2017 at 12:30 and 13:05 local time respectively.

Modified Mercalli intensities for some localities

The earthquake was widely felt throughout the central zone of Chile and in at least two provinces of Argentina.

Intensities of the earthquake on the scale of Mercalli in Chile according to ONEMI.

LocalityRegionUSGS[5]ONEMI[4]Population
AndacolloCoquimboIV11k
CanelaCoquimboV9k
CombarbaláCoquimboV13k
Coquimbo CityCoquimbo RegionV228k
IllapelCoquimboV31k
La Serena CityCoquimboV221k
Los VilosCoquimboV21k
Monte PatriaCoquimboV31k
OvalleCoquimboV111k
PaiguanoCoquimboIII4k
PunitaquiCoquimboV11k
Río HurtadoCoquimboIV4k
AlgarroboValparaísoVII14k
PuchuncavíValparaísoVII19k
Quillota CityValparaísoVIVI91k
Greater ValparaísoValparaísoVIVII951k
La LiguaValparaísoVI35k
El TaboValparaísoVI13k
ColinaMetropolitan RegionVI146k
MelipillaMetropolitan RegionVI124k
Puente AltoMetropolitan RegionVI568k
San BernardoMetropolitan RegionV301k
City of SantiagoMetropolitan RegionVVI6.310k (+6M)
TalaganteMetropolitan RegionVI74k
LituecheO'HigginsIV6k
NavidadO'HigginsVII7k
ParedonesO'HigginsIV6k
PichilemuO'HigginsIV16k
RancaguaO'HigginsIVVI242k
San FernandoO'HigginsIVVI74k
Santa CruzO'HigginsIV38k
CauquenesMauleV40k
ConstituciónMauleIV46k
CuricóMauleIV149k
LinaresMauleIII94k
Sagrada FamiliaMauleIV19k
CabreroBio-BioIII29k
Greater ConcepciónBio-BioIIIIV985k

Intensities of the earthquake on the scale of Mercalli in Argentina according to INPRES.

LocalityProvinceUSGS[5]INPRES[6]Population
City of San JuanSan Juan ProvinceIVIV447k
City of MendozaMendoza ProvinceIIIIV1.055k (+1M)

Earthquakes Foreshock

The first foreshock quake was recorded at 19:46 (local time) and 22:49 (UTC) on April 22, and had a magnitude of 4.8 Mw, with epicenter 32 km west of Valparaíso and 28.1 km deep.[7]

Precursor earthquakes magnitude greater than 5.0
Date Time local Location Coordinates Depth Magnitude MMI Agency.
April 22, 2017 23:36:07 30 km W of Valparaíso 33.02S, 71.95W 20 km 6.0 Mw VI EMSC.[8]
April 22, 2017 23:43:18 30 km W of Valparaíso 33.01S, 71.95W 20 km 5.0 Mw IV EMSC.[9]
April 23, 2017 16:40:10 45 km W of Valparaíso 33.044S, 72.148W 16 km 5.6 Mw IV NEIC.[10]

Aftershock

After the earthquake more than 1000 aftershocks were registered, the largest one had a magnitude of 6.0 Mw, with an epicenter 14 kilometers south of Valparaíso and 25.9 kilometers deep.[11]

Aftershock of magnitude greater than 5.0
Date Time local Location Coordinates Depth Magnitude MMI Agency.
April 24, 2017 18:45:58 121 km NW of Valparaíso 32.416S, 72.662W 25,9 km 5.5 Mw ? GUC.[12]
April 24, 2017 18:46:04 42 km W of Valparaíso 32.972S, 72.072W 16,4 km 5.2 mb VI NEIC.[13]
April 24, 2017 18:46:24 35 km WNW of Valparaíso 32.931S, 71.984W 16,4 km 5.4 mb VII NEIC.[14]
April 24, 2017 18:48:31 39 km WSW of Valparaíso 33.135S, 72.038W 17,1 km 5.0 mb VI NEIC.[15]
April 24, 2017 22:43:03 46 km W of Valparaíso 33.161S, 72.093W 23,9 km 5.5 Mw IV GUC.[16]
April 27, 2017 02:09:22 39 km SW of Valparaiso 33.265S, 71.956W 22,5 km 5.1 Mw VI NEIC.[17]
April 28, 2017 12:30:06 37 km WSW of Valparaiso 33.219S, 71.969W 22 km 5.9 Mw VII NEIC.[18]
April 28, 2017 12:33:28 47 km SW of Valparaiso 33.30S, 72.02W 20 km 5.1 mb V EMSC.[19]
April 28, 2017 12:49:41 47 km WSW of Valparaiso 33.240S, 72.080W 10 km 5.1 Mw V NEIC.[20]
April 28, 2017 12:58:33 44 km SW of Valparaiso 33.24S, 72.04W 15 km 5.4 Mw IV EMSC.[21]
April 28, 2017 13:05:57 14 km S of Valparaíso 33.166S, 71.662W 25,9 km 6.0 Mw VI GUC.[11]
April 28, 2017 14:41:49 40 km SW of Valparaiso 33.279S, 71.958W 18 km 5.3 Mw VII NEIC.[22]
April 28, 2017 22:46:02 36 km WSW of Valparaiso 33.216S, 71.962W 18,8 km 5.1 Mw V NEIC.[23]
May 13, 2017 13:54:47 30 km W of Valparaiso 32.95S, 71.93W 30 km 5.3 mb VII EMSC.[24]

Tectonic Summary

The April 24, 2017 M6.9 earthquake west of Valparaiso, Chile, occurred as the result of thrust faulting on or near the subduction zone interface between the Nazca and Pacific plates. At the latitude of this event, the Nazca Plate is moving towards the east-northeast at a velocity of 74 mm/year with respect to South America, and begins its subduction beneath the continent at the Peru–Chile Trench, 80 km to the west of the April 24 earthquake. The size, location, depth and mechanism of this event are all consistent with its occurrence on the megathrust interface in this region.[25]

While commonly plotted as points on maps, earthquakes of this size are more appropriately described as slip over a larger fault area. Events of the size of the April 24, 2017 earthquake are typically about 40x20 km in size (length x width).[25]

Chile has a long history of massive earthquakes, including the 2010 M 8.8 Maule earthquake in central Chile, which ruptured a ~400 km long section of the plate boundary immediately south of this 2017 event. The April 24, 2017 earthquake lies close to where the Juan Fernández Ridge enters the subduction zone, in a section of the plate boundary that ruptured in a M 8.0 earthquake in March 1985, and previously in the 1906 M 8.2 Valparaiso earthquake (reported by some to be as large as M 8.6). To the north of the Juan Fernandez Ridge, the subduction zone last ruptured in the M 8.3 Illapel earthquake in September 2015. This subduction zone also hosted the largest earthquake on record, the 1960 M 9.5 earthquake in southern Chile. Over the century prior to the April 24, 2017 earthquake, the region within 400 km of this event has hosted 19 M 7+ earthquakes. Prior to the April 24 M 6.9 event, the region immediately surrounding this earthquake hosted 9 other events of M 4.5 or larger over the preceding 2 days, including a M 5.9 earthquake on April 23, 2017. The 6.9 shock was also preceded by 4 seconds by a M~4 foreshock. Within an hour of the M 6.9 earthquake, 4 aftershocks of M 4.7-5.4 had been located.[25]

Magnitude of the earthquake
Rupture of the earthquake off the coast of Valparaíso.

This list includes information about the earthquake, which were measured by different seismological institutions worldwide.

Date Time local Time UTC Region Coordinates Depth Magnitude Agency.
April 24, 2017 18:38:28 21:38:28 offshore Valparaiso, Chile 33.089S, 72.116W 24,1 km 6.9 Mw GUC.[2]
April 24, 2017 18:38:27 21:38:27 offshore Valparaiso, Chile 33.03S, 71.85W 10 km 6.9 Mw EMSC.[3]
April 24, 2017 18:38:30 21:38:30 offshore Valparaiso, Chile 33.038S, 72.062W 28 km 6.9 Mw NEIC.[1]
April 24, 2017 18:38:21 21:38:21 off the coast of Valparaiso, Chile 33.072S, 72.298W 14 km 6.6 INPRES.[6]
April 24, 2017 18:38:29 21:38:29 near the coast of Valparaiso, Chile 33.02S, 71.86W 20 km 6.8 Mw GFZ.[26]
April 24, 2017 18:38:25 21:38:25 offshore Valparaiso, Chile 32.98S, 71.92W 10 km 6.7 Mw INGV.[27]
April 24, 2017 18:38:26 21:38:26 near the coast of Valparaiso, Chile 32.95S, 71.80W 20 km 6.9 Mw USP.[28]
April 24, 2017 18:38:26 21:38:26 offshore Valparaiso, Chile 33.073S, 72.051W 25 km 6.9 Mw AUST.[29]
April 24, 2017 18:38:25 21:38:25 off the coast of Valparaiso, Chile 33.056S, 72.042W 19 km 6.9 Mw IPGP.[30]

Tsunami
Tsunami recorded by the buoys on the coast of Valparaíso.

The National Office of Emergency of the Interior Ministry declared a tsunami warning for the coasts of the Valparaíso and O'Higgins regions.[31] A few minutes later, the National Tsunami Service of Chile (SNAM, by its initials in Spanish), dependent on the Hydrographic and Oceanographic Service of the Chilean Navy (SHOA, by its initials in Spanish), ruled out the probability of a tsunami off the coast of Chile.[32] However, if the tsunami was generated, according to the Pacific Tsunami Warning Center (PTWC) the maximum heights were; 16 cm in the city of Valparaíso and 10 cm in the commune of Quintero.[33]

gollark: Oh, it went back down again?
gollark: Ah, utsuho reiuji, a known alt account of... curiosity?
gollark: I accidentally misread it as 02/01/2021 somehow, so yes, they are PROBABLY maybe not an alt.
gollark: It seems like they joined before the banning, which is evidence against their altitude.
gollark: I have no actual proof so much as a vague suspicion which I'm voicing semiironically.

See also

References
  1. "M 6.9 - 40km W of Valparaiso, Chile". USGS. Retrieved 9 July 2018.
  2. "Informe de sismo sensible (in Spanish)". CSN-GUC. Retrieved 9 July 2018.
  3. "M 6.9 - OFFSHORE VALPARAISO, CHILE - 2017-04-24 21:38:27 UTC". EMSC. Retrieved 9 July 2018.
  4. "Sismo de mayor intensidad entre las regiones de Coquimbo y Biobío". ONEMI. Retrieved 9 July 2018.
  5. "M 6.9 - 40km W of Valparaiso, Chile (Pager)". USGS. Retrieved 9 July 2018.
  6. "Sismo sentido con epicentro en OCEANO PACIFICO (in Spanish)". INPRES. Retrieved 9 July 2018.
  7. "Informe de sismo sensible (in Spanish)". CSN-GUC. Centro Sismológico Nacional. Retrieved 9 July 2018.
  8. "M 6.0 - OFFSHORE VALPARAISO, CHILE - 2017-04-23 02:36:07 UTC". CSEM-EMSC. European-Mediterranean Seismological Centre. Retrieved 9 July 2018.
  9. "M 5.0 - OFFSHORE VALPARAISO, CHILE - 2017-04-23 02:43:18 UTC". CSEM-EMSC. European-Mediterranean Seismological Centre. Retrieved 9 July 2018.
  10. "M 5.6 - 48km W of Valparaiso, Chile". USGS-NEIC. National Earthquake Information Center. Retrieved 9 July 2018.
  11. "Informe de sismo (in Spanish)". CSN-GUC. Retrieved 9 July 2018.
  12. "Informe de sismo (in Spanish)". CSN-GUC. Centro Sismológico Nacional. Retrieved 9 July 2018.
  13. "M 5.2 - 42km W of Valparaiso, Chile". USGS-NEIC. National Earthquake Information Center. Retrieved 9 July 2018.
  14. "M 5.4 - 35km WNW of Valparaiso, Chile". USGS-NEIC. National Earthquake Information Center. Retrieved 9 July 2018.
  15. "M 5.0 - 39km WSW of Valparaiso, Chile". USGS-NEIC. National Earthquake Information Center. Retrieved 9 July 2018.
  16. "Informe de sismo sensible (in Spanish)". CSN-GUC. Centro Sismológico Nacional. Retrieved 9 July 2018.
  17. "M 5.1 - 39km SW of Valparaiso, Chile". USGS-NEIC. National Earthquake Information Center. Retrieved 9 July 2018.
  18. "M 5.9 - 37km WSW of Valparaiso, Chile". USGS-NEIC. National Earthquake Information Center. Retrieved 9 July 2018.
  19. "M 5.1 - OFFSHORE VALPARAISO, CHILE - 2017-04-28 15:33:28 UTC". CSEM-EMSC. European-Mediterranean Seismological Centre. Retrieved 9 July 2018.
  20. "M 5.1 - 47km WSW of Valparaiso, Chile". USGS-NEIC. National Earthquake Information Center. Retrieved 9 July 2018.
  21. "M 5.4 - OFFSHORE VALPARAISO, CHILE - 2017-04-28 15:58:33 UTC". CSEM-EMSC. European-Mediterranean Seismological Centre. Retrieved 9 July 2018.
  22. "M 5.3 - 40km SW of Valparaiso, Chile". USGS-NEIC. National Earthquake Information Center. Retrieved 9 July 2018.
  23. "M 5.1 - 36km WSW of Valparaiso, Chile". USGS-NEIC. National Earthquake Information Center. Retrieved 9 July 2018.
  24. "M 5.4 - OFFSHORE VALPARAISO, CHILE - 2017-04-28 15:58:33 UTC". CSEM-EMSC. European-Mediterranean Seismological Centre. Retrieved 9 July 2018.
  25. "M 6.9 - 40km W of Valparaiso, Chile". United States Geological Survey. Retrieved 10 July 2018. This article incorporates text from this source, which is in the public domain.
  26. "Near Coast of Central Chile". GFZ. German Research Centre for Geosciences. Retrieved 9 July 2018.
  27. "Terremoto di magnitudo Mwp 6.7 del 24-04-2017 ore 23:38:25 (Italia) in zona: Chile (Peruvian point of view) [Sea]". INGV. National Institute of Geophysics and Volcanology. Retrieved 9 July 2018.
  28. "Near Coast of Central Chile (in Portuguese)". USP. University of São Paulo. Retrieved 9 July 2018.
  29. "Earthquake Details". AUST. Geoscience Australia. Retrieved 9 July 2018.
  30. "OFF COAST OF CENTRAL CHILE 2017/04/24 21:38:25 UTC, Mw=6.9". IPGP. Institut de Physique du Globe de Paris. Retrieved 9 July 2018.
  31. "Sismo de 7.1 grados afectó a zona centro del país y generó alerta preventiva de tsunami" (in Spanish). El Dínamo. 24 April 2017. Retrieved 9 July 2018.
  32. "Onemi cancela evacuación preventiva en Valparaíso y O'Higgins tras sismo de 6,9 grados Richter" (in Spanish). La Tercera. 24 April 2017. Retrieved 9 July 2018.
  33. "2227 UTC MON APR 24 2017". Pacific Tsunami Warning Center. Retrieved 9 July 2018.
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