In this 30-day time series, the x-axis shows time, starting with the first large earthquake (magnitude-6.4) on Oct. 16. The y-axis shows distance from Mount Apo, with both volcanoes labeled. The light blue band shows the region around Mount Apo and Mount Talomo. The initiation of seismicity below these volcanoes after the magnitude-6.5 earthquake is evident. Credit: Geoffrey Ely, Temblor

In this 30-day time series, the x-axis shows time, starting with the first large earthquake (magnitude-6.4) on Oct. 16. The y-axis shows distance from Mount Apo, with both volcanoes labeled. The light blue band shows the region around Mount Apo and Mount Talomo. The initiation of seismicity below these volcanoes after the magnitude-6.5 earthquake is evident. Credit: Geoffrey Ely, Temblor

In this 30-day time series, the x-axis shows time, starting with the first large earthquake (magnitude-6.4) on Oct. 16. The y-axis shows distance from Mount Apo, with both volcanoes labeled. The light blue band shows the region around Mount Apo and Mount Talomo. The initiation of seismicity below these volcanoes after the magnitude-6.5 earthquake is evident. Credit: Geoffrey Ely, Temblor

Follow her

Alka Tripathy-Lang, PhD

Alka Tripathy-Lang is a freelance science writer based in Chandler, Arizona, and holds a Ph.D. in geoscience.
Follow her