What is it?
A volcano is a vent at the earth's surface through which magma (molten rock) and associated gases erupt, and also the cone built by effusive and explosive eruptions. Although there aren't any cone-shaped volcanoes in Teton County, we do have several volcanically active areas in and around Yellowstone National Park.
The reason that Yellowstone has so many amazing thermal features such as geysers, mudpots, and fumaroles is the volcanic activity underneath the surface. Yellowstone has a large caldera, which is a collapsed volcano, that encompasses a large portion of the park. Most people don't realize as they drive into the central geyser basins in Yellowstone, that they are actually driving into a volcano! Check the map below to look at the region that the Yellowstone caldera encompasses. Teton County extends to the southwestern edge of Yellowstone Lake, so technically part of the caldera is in our county:
Click for a larger view
I'm sure many of you have seen, or at least have heard of, the docu-drama "Supervolcano". One of the more popular questions Emergency Management has received following this production is, "Will that happen here?" The answer is that we don't know for sure, but we will prepare our citizens by teaching them about the risk, and also give them instructions on how to prepare. The National Park Service and the USGS set up a great website answering some of the more common questions that have come up in regards to the "Supervolcano" movie, and you can access that page here.
What are the risks?
Since catastrophic geologic events occur so rarely, it is difficult to calculate the exact risks of another event, but that is no reason to be unprepared:
Proximity to a volcanically active area.
There is debate among scientists what is considered "active". The last eruption of the Yellowstone caldera occurred about 70,000 years ago, while the last catastrophic eruption was 600,000 years ago. The largest eruption was approximately 2 million years ago, and the diagram below puts those eruptions into context:
Click for larger view
Although the last eruption was around 70,000 years ago, most geologists agree that the Yellowstone caldera is still active. The Yellowstone Volcano Observatory is one of five USGS volcano observatories in the United States. In partnership with the University of Utah and the National Park Service, the observatory constantly monitors the status of the Yellowstone caldera for any abnormalities and continuously records geologic data. Each month they provide a report on geologic activity in the area, which is available on their website.
With all of that said, many scientists do not know if Yellowstone's caldera will ever have another catastrophic eruption. Based on Yellowstone's past history, the possibility of another caldera-forming eruption is 0.00014%. Realize, however, that this is only based on the 3 past major eruptions, so it is hardly close to being statistically accurate. Either way, there is currently no evidence to suggest that a catastrophic event at Yellowstone is imminent, and such events are unlikely to occur in the next few centuries (USGS).
Historically there have been smaller eruptions and lava flows in Yellowstone as well, and it is possible for these to occur again. Scientists, however, have no evidence to suggest that these types of events will occur in the near future either.
Living downstream along the predominant jetstream from other volcanically active areas.
Teton County can be affected by a volcano without the eruption of the Yellowstone caldera. One of the most volcanically active areas in the United States today is the Pacific Northwest. Since Teton County lies to the east of this area (which is the predominant wind direction), we can be affected by ash and other gases as they are carried away from the eruption site.
In the diagram to the right (courtesy of the Seattle Times), you can see how within 9 hours the ash plume from the May 18, 1980 eruption of Mount St. Helens reached Teton County. Although we only received a dusting, there were several citizens who were taken to the hospital due to respiratory issues from the ash.
After looking at the ash distribution from the Mount St. Helens eruption, look again at this diagram to put it into context with the major eruptions of the Yellowstone caldera. Then click on the map to the left to see how the ash fall from Mount St. Helens compares to that of the prehistoric eruptions of the Yellowstone caldera.
What should I do?
Information and advance warning are key to reacting to a volcanic event:
As for any disaster, have a plan and preparedness kit ready for your family.
If you don't have a family emergency plan and a 72 hour kit, click here to get started.
Have a pair of goggles and disposable breathing mask for every family member in your 72 hour kit.
These items should be in your kit anyway due to their usefulness not only in a volcanic event, but in the event of pandemic flu, earthquake, or any others where there are particulates in the air that you don't want to have in contact with your eyes or respiratory system.
Volcanic ash is essentially pulverized rock and glass which is abrasive, gritty, gassy, and odorous. Although it is not immediately dangerous to most adults, infants or the elderly are particularly at risk. Those with respiratory problems also need to take special precautions. If available, everyone should wear respiratory masks. If not available, a damp cloth held over the nose and mouth can help to filter out the ash.
If you wear contact lenses, you should remove them. They can trap irritants against your eye or may react to the gases carried by the wind from the eruption. Everyone should wear eye protection if available.
Stay tuned to EAS broadcasts for instruction before, during, and following the disaster.
Listen to your NOAA All-Hazards Weather Radio or another Emergency Alert System (EAS) broadcaster for instructions from emergency services before, during, and following a disaster. Lava flows are typically slow moving, so evacuation orders can be given well in advance. Emergency services will also give instruction on how to deal with ash or whether it will be necessary to shelter in place.
If told to evacuate, do so immediately.
It is also important that you follow the routes given to you for evacuation by emergency services. Some roads may be impassable due to landslides, ash fall, or lava flows.
Wear long sleeve shirt and pants.
This will reduce the amount of contact your skin has with abrasive and irritating ash.
Stay indoors until the ash has settled, unless there is danger of roof collapse.
It will be easier to get around once the ash has settled, but especially if it begins to rain be aware that ash can become very heavy. Try to monitor the amount of ash on your rooftop and make arrangements to remove it if it becomes too heavy.
Use shelter in place procedures.
Shut all windows, doors, and vents. Turn off any HVAC units that may be bringing ash into the structure.
Clear heavy ash from flat or low-pitched roofs.
Luckily in Teton County, many structures are designed with roofs to slough off snow in the winter, which will also help with shedding volcanic ash in the event of an eruption. If ash does accumulate, shovel it off of the roof and out of gutters while wearing goggles, a dust mask, and long pants and shirt.
Avoid running engines or driving in heavy ash fall.
Volcanic ash can easily clog engines, damage moving parts, and stall engines with its abrasive properties. Also, driving in depths of ash is not like driving in deep snow; as mentioned before, ash can easily clog engines and stall out vehicles.
Ready.gov has a site with information on volcanoes and what to do in the event of an eruption. The USGS also has some detailed information on volcano monitoring, preparedness actions, and more here.
What are the impacts?
A catastrophic large-scale eruption of the Yellowstone caldera would have dire impacts on the entire world, and not just Teton County. To learn about those, check the Yellowstone Volcano Observatory FAQ here. Impacts discussed below are considering smaller eruptions:
Loss of life and damage to property.
Loss of life is the primary impact, and secondary to that is the damage to property. Ash, being made of pulverized rock and glass, can get into ventilation systems, engines, and buildings rendering vehicles and structures unusable.
Even a non-catastrophic volcanic eruption is a large-scale event. Like an earthquake, it is the other disasters that are triggered by the volcano that can make the event even more complicated. Volcanoes can trigger landslides, avalanches, flash floods, wildfires, weather such as acid rain, and other disastrous events.
A long and expensive recovery effort.
Even without lava flows and pyroclastic events, the amount of ash that can be deposited following an eruption presents an expensive logistical problem for affected communities. Ash and lava can cause extensive damage to critical infrastructure and utilities as well.
Not only is the recovery effort expensive, but if people are unable to leave their homes due to hazardous conditions outside, businesses will suffer.