Boom goes the PETN explosive… at UB’s Geohazards Field Station

One of four blast tests conducted in July 2018 at the University at Buffalo Geohazards Field Station in Ashford, New York. Video credit: Arianna Soldati, Ludwig Maximilian University 

Release Date: July 27, 2018

“This is the only place in the world where they are using chemical explosives to try and mimic processes from a volcanic eruption.”
Arianna Soldati, postdoctoral researcher
Ludwig Maximilian University

In a forest clearing at the end of a steep gravel road, UB geologist Andrew Harp poured sand into a hole loaded with dynamite-like explosive charges.

It was a quiet day. Tall grasses rose in the distance. Wildflowers — purple, white and yellow — caught the breeze. A bird call sounded.

Minutes later, an air horn blew.

Then, a countdown: FIVE… FOUR… THREE… TWO… ONE.

BOOM!

Six explosions detonated in quick succession, throwing plumes of sand and crushed limestone into the air.

Applause broke out. Then, about 50 people, mostly scientists interested in volcanoes, dispersed from their perch on a nearby slope to check on research equipment and scrutinize the crater left behind by the blasts.

Welcome to the Field-Scale Experimental Volcanology Workshop run by the University at Buffalo Center for Geohazards Studies. Taking place from July 24-27, the event — supported by the National Science Foundation — drew participants from as far away as Italy and Japan.

A scientist filming the explosions from a distance.

Volcanologist Arianna Soldati watches one of four blast tests that took place. Prior to the explosion — Soldati, a postdoctoral researcher at Ludwig Maximilian University — set up a 3-D, 360-degree camera to collect data closer to the blast site. Credit: Meredith Forrest Kulwicki

Thursday was Blast Day. It featured four explosive tests spaced throughout the morning and afternoon at UB’s Geohazards Field Station in Ashford, New York. The experiments employed an explosive material called PETN to simulate violent phenomena that occur during volcanic eruptions (Twitter hashtag: #uBLASTworkshop).

“This is the only place in the world where they are using chemical explosives to try and mimic processes from a volcanic eruption,” said attendee Arianna Soldati, a postdoctoral researcher at Ludwig Maximilian University and recent PhD graduate in geological sciences from the University of Missouri-Columbia.

Researchers working in a large clearing on a foggy day.

On a hazy morning on July 26, researchers prepare scientific equipment in preparation for the blast tests. Photo: Meredith Forrest Kulwicki

“It’s a controlled experiment,” said Greg Valentine, professor of geology in the UB College of Arts and Sciences and director of the Center for Geohazards Studies. “We know what the conditions are that create the explosion. We know the pressure, the gas content, the depth of the explosion, the strength of the explosion.”

So how does this relate to real-world volcanoes? If you know how the ground shakes or how debris flies in a controlled blast, you can use this data to gain insight into the forces that drive explosive eruptions in nature.

'No one university or scientific group has all of this'

A scientist stands over three white PVC tubes sticking up out of the ground.

Andrew Harp, a recent UB geology PhD graduate, works on a blast pad. The white tubes mark locations where explosive charges will be placed. Harp helped to plan the workshop. Credit: Meredith Forrest Kulwicki

At the field station, preparations for Thursday’s blasts began early on Wednesday. It was hot and stifling, a damp morning with silver clouds hanging in the sky.

In the clearing, Kyle Comstock, a UB undergraduate, armed himself with a shovel and pickaxe. He was there to help Greg Waite, a geophysicist at Michigan Technological University (Michigan Tech), dig a 1.6-meter-deep hole where seismometers would be buried at varying depths.

Three white PVC tubes sticking up from the ground.

A blast pad. The white tubes mark locations where explosive charges will later be placed. Credit: Meredith Forrest Kulwicki

Elsewhere, other participants were busy erecting an amalgam of scientific instruments to document each blast.

There were research-grade microphones (Brigham Young University, led by physicist Tracianne Neilsen). There were infrasound sensors and more seismometers (the University of California, Santa Barbara, led by volcanologist Robin Matoza). There was a missile-shaped ballistic sensor for detecting supersonic jets (Michigan Technological University, led by Ezequiel Médici, a mechanical engineering faculty member).

Some tools were decidedly low-tech: Alison Graettinger, an assistant professor of geosciences at the University of Missouri-Kansas City, directed a team in lining shallow cardboard boxes with plastic sheeting.

A scientist combining two shallow boxes of debris.

Julia Boyd, a student from the University of Missouri-Kansas City, was part of a team that studied debris thrown out by the explosion. The debris, called ejecta, was collected in shallow boxes placed at varying distances from the epicenter. Credit: Meredith Forrest Kulwicki

Later, these receptacles would be placed at varied distances from the epicenter of blasts. The goal? To catch and measure the distribution of debris, called “ejecta.”

“No one university or scientific group has all of this,” Soldati said. “We are going to know everything about these explosions.”

Soldati ran a 3-D, 360-degree camera. Colleagues from other institutions took videos from drones and high-speed cameras. Some did photogrammetry, creating 3-D models of the blast craters for future research.

This kind of open-ended research was exactly what organizers — including Valentine; Ingo Sonder, lead experimental scientist at the Center for Geohazards Studies; and Harp, a recent UB geology PhD graduate — had in mind. Instead of designing the workshop to answer one specific question, they planned the experiments to be useful to scientists working in many different fields.

A field station where things go boom

Debris flies into the air.

Debris flies during one of the workshop's four explosive tests. Credit: Meredith Forrest Kulwicki

At real volcanoes, explosions can happen under varied circumstances: when hot gases get trapped, for example, or when water and magma meet.

Understanding real-world blasts — and the risk that volcanoes pose — was a shared objective of workshop participants. One example: Médici, the Michigan Tech engineer, hopes to develop early warning systems for volcanic ash, which could help air traffic controllers.

A bright pink sphere sitting in a hole, with a tape measure sticking out.

A spray-painted sphere is buried at a known location and depth before the blasts. By tracking where these projectiles land after an explosion, scientists can gain information about the dynamics of a blast. The balls were homemade, crafted earlier in the week from plaster injected into ping pong balls that were later cut away. Credit: Sierra McCollum

Graettinger, a former UB postdoc who returned with her students for the workshop, led post-blast activities like on-the-ground photography of craters (to be used later in photogrammetry) and measurements of ejecta.

Tasks included hunting down brightly colored spheres that were buried before the blasts at known locations. The balls were homemade, crafted earlier in the week from plaster injected into ping pong balls that were later cut away.

“This work really focuses on how eruptions evolve and the evidence they leave behind,” Graettinger explained in an email a few weeks before the blasts. “Being able to better read those deposits and craters left by past eruptions will help with our understanding of what happened before and anticipate what can happen in the future. This will help numerical models and conceptual models of what happens during explosions and after.”

Five scientists in casual clothing standing above a crater.

Alison Graettinger (center, in white shirt) led post-blast activities like photography of craters and measurements of ejecta. Graettinger is an assistant professor of geosciences at the University of Missouri-Kansas City who previously conducted postdoctoral research at UB. Credit: Meredith Forrest Kulwicki

In her message, Graettinger discussed the UB Geohazards Field Station and the unique experiments the set-up there enables.

Melting rocks to make lava, and injecting that lava with water? Check. Detonating ping pong balls to model eruptions? Thursday’s tests were a continuation of this brand of work, giving volcanologists the rare opportunity to conduct controlled experiments at a scale larger than what can occur in the lab.

“The workshop and the field station provide a unique opportunity to ask new and better questions about how we understand volcanic processes,” Graettinger wrote in her email. “We can tell our analog volcanoes when to erupt, and calibrate our techniques and instruments before taking them out to dangerous and messy real volcanoes.”

Trees rise at the side of a clearing on a hazy day.

The UB Geohazards Field Station. Credit: Meredith Forrest Kulwicki

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