·

Geoarchaeological evidence reveals a major M9.5 tsunamigenic earthquake in Chile

evidence for major megathrust earthquake chile about 3800 years ago

A new study published this week in Science Advances presents geoarchaeological evidence revealing a major M~9.5 tsunamigenic earthquake that severely affected prehistoric hunter-gatherer-fisher communities some 3 800 years ago, causing an exceptional social disruption reflected in contemporary changes in archaeological sites and triggering resilient strategies along these coasts.

  • Together with tsunami modeling results, researchers suggest that this event resulted from an approximately 1 000 km (620 miles) long megathrust rupture along the subduction contact of the Nazca and South American plates, highlighting the possibility of Mw ~9.5 tsunamigenic earthquakes in northern Chile, one of the major seismic gaps of the planet.
  • The waves this earthquake produced might have reached 15 – 20 m (49 – 66 feet) high.
  • Researchers hypothesize that his event could have generated a very high mortality among people, or it could have also prompted the migration of a significant number of people to other territories.

“Since the beginning of the present millennium, a cluster of giant earthquakes has occurred around the world with notable social consequences including the loss of more than 700 000 human lives,” researchers said.

“These include the giant megathrust earthquakes of moment magnitude (Mw) ~9.1 Sumatra-Andaman (2004); Mw 8.8 Maule, central Chile (2010); and Mw 9.1 Tohoku-Oki (2011), which caused large tsunamis that severely affected adjacent coasts and produced transoceanic effects.”

In the new study, researchers provide geoarchaeological evidence revealing a major tsunamigenic earthquake estimated at Mw ~9.5 and tsunami waves as high as 15 – 20 m (49 – 66 feet) that severely affected prehistoric hunter-gatherer-fisher communities some 3 800 years ago.

Geological and archaeological evidence for the event derives from uplifted littoral beach and paleotsunami deposits, erosional contacts, and fractures in archaeological sites. Geological evidence from these and previous observations shows conspicuous littoral deposits located up to 6 to 7 m (20 – 23 feet) above the present mean sea level.

evidence for major megathrust earthquake chile about 3800 years ago
Tectonic plates setting, major historical tsunamigenic megathrusts, sites, and tsunami modeling results supporting a Mw ~9.5 earthquake scenario ~3800 cal yr B.P. in northern Chile.(A) Proposed ca. 1000-km-long megathrust rupture for a ~3800 cal yr B.P. tsunamigenic earthquake, encompassing three major segments in front of Iquique, Taltal, and Atacama regions. (B) Sites of geological and archaeological observations for coastal uplift and paleotsunami deposits dated to ~3800 cal yr B.P. and tsunami modeling results. 1: Pabellón de Pica; 2: Paquica Sur; 3: Cobija; 4: Michilla; 5: Playa Grande de Mejillones; 6: Mejillones Peninsula; 7: Zapatero; 8: San Ramón-15 mine; 9: Los Bronces; 10: Hornos de Cal; 11: Playa San Pedro; 12: Bahía Cisne, Caldera. (C) Tsunami run-ups associated with the major historical tsunamigenic earthquakes of 1868, 1877, and 1922 CE in northern Chile (from National Hydrographic and Oceanographic Service). (D) Map showing tectonic plates coupling indicating a high potential for large megathrust earthquakes along northern Chile. (E) Seismotectonic setting along northern Chile, with the subduction of the Nazca plate beneath the South American plate and historical megathrusts ruptures. Credit: Diego Salazar et al., Science Advances

The tsunamigenic earthquake described in the paper is contemporary with major changes in the settlement system of local hunter-gatherer communities, which had inhabited this coastline for nearly 10 millennia before this event.

“Although there are limitations in some of the available datasets, changes are consistent at different spatial scales, from individual sites to the entire hyperarid coast of the Antofagasta and Tarapacá regions, considering independent lines of evidence,” the researchers said.

The study emphasizes the necessity to account for long temporal scales to better understand the variability, social effects, and human responses favoring resilience to socionatural disasters.

Reference:

Did a 3800-year-old Mw ~9.5 earthquake trigger major social disruption in the Atacama Desert? – Diego Salazar et al. – Science Advances – April 6, 2022 –DOI: 10.1126/sciadv.abm2996 – OPEN ACCESS

Featured image credit: Diego Salazar et al., Science Advances

If you value what we do here, create your ad-free account and support our journalism.

Share:

Related articles

Producing content you read on this website takes a lot of time, effort, and hard work. If you value what we do here, select the level of your support and register your account.

Your support makes this project fully self-sustainable and keeps us independent and focused on the content we love to create and share.

All our supporters can browse the website without ads, allowing much faster speeds and a clean interface. Your comments will be instantly approved and you’ll have a direct line of communication with us from within your account dashboard. You can suggest new features and apps and you’ll be able to use them before they go live.

You can choose the level of your support.

Stay kind, vigilant and ready!

$5 /month

  • Ad-free account
  • Instant comments
  • Direct communication
  • New features and apps suggestions
  • Early access to new apps and features

$50 /year

$10 /month

  • Ad-free account
  • Instant comments
  • Direct communication
  • New features and apps suggestions
  • Early access to new apps and features

$100 /year

$25 /month

  • Ad-free account
  • Instant comments
  • Direct communication
  • New features and apps suggestions
  • Early access to new apps and features

$200 /year

You can also support us by sending us a one-off payment using PayPal:

Leave a reply