The three explorers met by chance.

Stephanie Grocke 


Gabby Salazar


Ross Donihue


They all attended a meeting of scientists and adventurers at National Geographic headquarters nearly three years ago. It took only a few minutes for volcanologist Stephanie Grocke to realize that photographer Gabby Salazar and cartographer Ross Donihue would make perfect partners. Grocke wanted to tell the story of a volcanic system she had been studying in Guatemala. And it took only a few minutes for Salazar and Donihue to know that they were hooked. 

An Explosive Start

There’s a mystery Grocke wants to help solve, she explained. At the base of the Santa María volcano in Guatemala is an area where several domes of lava have formed.

In 1902, Santa María experienced a huge eruption. It ranked as one of the largest volcanic eruptions of the 20th century.

The event destroyed the surrounding landscape and left a huge crater in the side of the mountain. It also deposited a thick layer of ash and volcanic debris. New lava flows began erupting at the base of Santa María in 1922. Over time, the flowing lava created an entire lava dome complex. It is called Santiaguito.

Eruptions expel pumice, a light and porous volcanic rock.

A plume of ash from an eruption rises above the clouds.

Lava domes are formed when sticky magma erupts from a vent. It then pours onto Earth’s surface. The lava is too thick and gooey to flow far. Instead, it piles up and makes a large dome.

The first dome to form was called Caliente. Magma then created a second lava dome, La Mitad. The magma moved west again to build El Monje and then El Brujo. Finally, the magma moved back to El Caliente, where it is currently erupting.

A Place to Study

Since 1922, there have been small, continuous eruptions among the four lava domes. The eruptions happen so often, they feel routine to those living nearby. The residents in the town of Quetzaltenango have put up with it for the last 96 years.

To Grocke, this place is the perfect place to be. It’s a natural laboratory for studying active volcanoes. And it’s a good place to test a new method to monitor lava dome activity.

So, she planned a month‑long expedition with Salazar and Donihue. Grocke wanted to use cutting‑edge photogrammetry techniques to study the active lava dome. This is a type of time‑lapse photography. It allows you to observe changes over a period of time. She knew Salazar could help with this and also film eruptions as they happened.

Donihue would map their expedition. He would also make infographics to showcase the complexity and risks of active volcanoes. With Grocke’s volcanic know‑how, Salazar’s high‑tech photography, and Donihue’s advanced mapping skills, the team was ready.

Santiaguito Complex

The 1902 eruption of Santa María produced a huge crater. Over time, four lava domes formed at its base.

seismic monitoring station

Santa María

El Caliente

La Mitad

El Monje

El Brujo