Jump to content

Wikipedia:Main Page history/2023 January 21

From Wikipedia, the free encyclopedia

Welcome to Wikipedia

,
6,605,898 articles in English

From today's featured article

Satellite image of the caldera, the gray-yellow area at lower centre left
Satellite image of the caldera, the gray-yellow area at lower centre left

The Cerro Blanco is a caldera in the Andes, located in Argentina's Catamarca Province. Part of the Andes' Central Volcanic Zone, it is a volcano collapse structure located at an altitude of 4,670 metres (15,320 ft) in a depression. It has been active for the last eight million years and its eruptions have created several ignimbrites. An eruption 73,000 years ago formed the Campo de la Piedra Pómez ignimbrite layer, while another eruption in 2,300 ± 160 BCE became the largest volcanic eruption of the Central Andes, and reached the highest level in the Volcanic Explosivity Index, ejecting an estimated 170 cubic kilometres (41 cu mi) of tephra. This eruption led to the formation of the most recent caldera, as well as thick ignimbrite layers. However, the Cerro Blanco has been dormant since then, although some deformation and geothermal activity have been recorded. The volcano is also known for giant ripple marks that have formed on its ignimbrite fields. (Full article...)

Recently featured:

Did you know ...

Forest Park Carousel
Forest Park Carousel

In the news

Chris Hipkins
Chris Hipkins

On this day

January 21

Members of the First Dáil
Members of the First Dáil
More anniversaries:
Rega

Rega is a private, non-profit air rescue service that provides emergency medical assistance in Switzerland and Liechtenstein. It was established in 1952 by Dr Rudolf Bucher, who believed the Swiss rescue organization needed a specialized air sub-section. This image is a sequence photograph, stitched from 207 separate frames, of Rega's rescue helicopter Da Vinci in operation in Stoos, Switzerland.

Photograph credit: Roy Egloff

Other areas of Wikipedia

  • Community portal – The central hub for editors, with resources, links, tasks, and announcements.
  • Village pump – Forum for discussions about Wikipedia itself, including policies and technical issues.
  • Site news – Sources of news about Wikipedia and the broader Wikimedia movement.
  • Teahouse – Ask basic questions about using or editing Wikipedia.
  • Help desk – Ask questions about using or editing Wikipedia.
  • Reference desk – Ask research questions about encyclopedic topics.
  • Content portals – A unique way to navigate the encyclopedia.

Wikipedia's sister projects

Wikipedia is written by volunteer editors and hosted by the Wikimedia Foundation, a non-profit organization that also hosts a range of other volunteer projects:

Wikipedia languages