Social Media Posts Reveal Human Responses to Deadly Tongan Eruption
The January 2022 eruption of Hunga Tonga–Hunga Ha’apai was one of the most powerful ever recorded. It generated atmospheric shock waves that circled the globe several times, and its impact claimed the lives of six people, including two in Peru, 9,600 kilometers from Tonga.
In the aftermath of the eruption, social media videos showed the nation of Tonga engulfed by ash and tsunami waves. Now scientists are examining these videos to quantify human responses and improve warning systems and will present their research on December 15 at AGU’s Fall 2022 meeting.
“To measure the social response to events as complex as this [is] difficult, other than through interviews afterward,” said Jacob Lowenstern, a volcanologist with the US Geological Survey (USGS) and director of the Volcano Disaster Assistance Program who was not involved in the study. However, quantifying that societal response can improve disaster preparedness in the future.
Prediction of unpredictable reactions
People behave unpredictably during disasters, said Dare Baldwin, a psychologist at the University of Oregon who contributed to the study. “It’s important to understand the diversity of responses so we can tailor education and early warnings for different people.”
To improve messaging and warning systems in hazard-prone areas, Sara McBride, a USGS social scientist who will present the research, used closed-circuit television footage and social media clips to gauge how people reacted to the Tongan eruption .
“A lot of physical scientists talk about how unique this event was,” McBride said. “We also wanted to understand people’s behavior during the crisis, while respecting the enormous challenges they faced.”
The researchers collected 480 videos posted to Reddit, Twitter, TikTok and YouTube after the event, including 180 videos filmed in Tonga itself, plus tsunami footage from 11 countries across the Pacific.
McBride and a team of geoscientists and social scientists — including Tongan researchers and those involved in the Pacific tsunami response — watched the videos to identify what people did during and after the event.
They analyzed the videos using a method previously established to quantify the response to earthquakes. This included noting if people were evacuating, taking cover or protecting others, for example.
Shirley Feldmann-Jensen, professor of emergency services administration at California State University, Long Beach, and a pioneer of the video analysis method, said she is pleased to see other researchers applying the technique to different natural disasters. “Knowledge of what people actually do, rather than what they report doing, informs improved education and preparation for such events.”
One eruption, multiple dangers
The videos captured an ash cloud erupting over Tonga. This was closely followed by at least 13 separate shock wave-type landfalls around the archipelago that coincided with tsunami waves moving across the Pacific Ocean.
Baldwin said the eruption’s onset and early shock waves may have warned nearby communities of the devastating effects to come. “What was hopeful was that we saw quite a few videos where it looked like people were taking proactive protective action, such as filming from above and a fair distance from shore,” she said. Similarly, McBride noted that people tended to evacuate once they saw tsunami waves breaking seawalls.
But when faced with multiple hazards, such as earthquake and tsunami effects, the response was more haphazard. Under these circumstances, people tended to congregate with others rather than protect themselves by seeking shelter or high ground. “We’ve seen that exposure to cascading hazards like this can really confuse people, and understandably so,” McBride said.
The findings highlighted the growing need for multi-hazard training, McBride said. Every year, millions of people around the world practice earthquake drills by participating in the Great ShakeOut, but multi-hazard drills are much more rare. Currently, New Zealand is leading the way with its multihazard ShakeOut, which includes an earthquake drill and a tsunami hīkoi (evacuation walk).
It makes sense to combine these exercises, McBride said, both to save time and to better simulate concurrent hazards. Multi-hazard exercises can prepare communities to respond and clear up dizzying hazards that might otherwise confuse life-and-death decisions.
—Erin Martin-Jones (@Erin_M_J), Science writer