Sonja Sekula (April 8, 1918-April 25, 1963) was a Swiss-born artist linked with the abstract expressionist movement.
Biography on Wikipedia: https://en.wikipedia.org/wiki/Sonja_Sekula

Spain by Sonja Sekula
1954 / Opaque colors on paper / 19 3/10″x12 1/2″/ Kunst Museum Winterthur, Winterthur, Switzerland
Sonja Sekula on Artnet: http://www.artnet.com/artists/sonja-sekula/
Further reading:
https://www.sikart.ch/KuenstlerInnen.aspx?id=4026515
https://www.peterblumgallery.com/artists/sonja-sekula/biography
https://www.sarahlawrence.edu/news-events/news/2019-10-03-overdue-recognition-for-abstract-expressionist-and-alumna-sonja-sekula-fs.html