The animated map below shows a time-lapse ... a powerful magnitude-7.6 earthquake shook Marmara, a densely populated region to the south of Istanbul, Turkey’s largest city, for 45 seconds.

For months, the surface waters of Turkey’s Sea of Marmara have been full of a viscous substance colloquially referred to as “sea snot.” The cloudy muck, formally referred to as marine mucilage, has ...