Where is that lava headed and when will it get there?

(BIVN) – From this week’s US Geological Survey Hawaiian Volcano Observatory Volcano Watch article, written by postdoctoral researcher David Hyman:

When lava flows erupt on the flanks of Kīlauea or Mauna Loa, Hawaii residents and emergency management agencies want to know what to expect.

During the 2018 Kīlauea Lower East Rift Zone eruption, 24 fissure lava flooded more than 8,000 acres (3,200 hectares) of land in the Puna district and more than 700 structures were destroyed. Sobering data such as these highlight the need to predict the advancement of lava flows to help emergency handlers, residents and staff of the USGS Hawaiian Volcano Observatory (HVO). Highly accurate predictions for other natural hazards such as hurricanes, floods, droughts, and even the spread of vog from Kīlauea are now on the agenda. Can we do the same for lava flows?

The most successful prediction efforts for other natural hazards rely on the ability to simulate water or air flows. While the movement of these fluids is typically much more complex than that of lava, we know a lot more about water and air than lava as a material. After all, we can’t see inside a lava flow to observe what’s happening below the surface as we can for water and air.

At the heart of the hazard predictions are computer algorithms that process the numbers as fast as possible to make a relevant prediction. After all, a forecast of severe flooding in 24 hours isn’t very useful if it takes 23 hours to make that forecast.

Although researchers have been applying the principles of fluid dynamics to lava flows for over 40 years, most simulations are too slow to use during a crisis when we really want to know the answer to the questions: where is that lava headed and when will it get there?

To help answer this question, HVO scientists have predicted the general path of lava flows for many years using the steeper descent principle – that lava flows downhill. In many cases, these predictions have worked really well; however, this method alone cannot answer the second part: “… and when will it arrive?” because it only predicts the path, not the speed or the final length of the stream.

To help answer these questions, USGS scientists are developing a new lava flow prediction model based on the physical simulation of lava flowing through real topography as it cools and solidifies. This model is designed with simplified yet realistic physics, allowing simulation of 24 hours of lava advancement in just a couple of minutes on a regular laptop.

This research is supported by the Additional Supplemental Disaster Relief Act of 2019 (HR 2157), which has also funded the work of many HVO projects that have been the subject of recent “Volcano Watch” articles.

Of course, we don’t have perfect knowledge or measurement of our model’s inputs, so a single simulation doesn’t provide much information about our confidence in a prediction. By running the code many times with a range of inputs, the collection, or collection, of all of these models can give us a much better idea of ​​the range of possible results. This has been a common practice for many years in predicting dangerous weather conditions such as hurricanes and is now at the forefront of volcanic hazard research. HVO scientists are investigating how to produce ensembles using this new model, with the aim of successfully predicting lava flooding during future eruptions.

While there are many things we don’t know about what a volcano is going to do, we can make some short-term predictions based on what is currently happening. These predictions, even over short periods of time, give people on the lava flow path the ability to plan, providing critical answers to the questions: “Where is that lava headed and when will it get there?”

Join us next week for two programs on the first anniversary of the eruption of the summit of Kīlauea volcano in Hawai’i Volcanoes National Park. On September 27 at 7pm, a presentation of After Dark in the Park by HVO deputy scientist David Phillips; and on September 29 at 3 pm, a “Year on the Edge” speech by a Hawaii Volcanoes National Park ranger and HVO scientist. Details on these talks are posted on the Hawaii Volcanoes National Park website. Email askHVO@usgs.gov for more information.

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