Thurston County Connection Newsletter
Thurston County Connection
Thurston County Connection
September, 2014
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This Month's Articles

Back-to-School Safety 101:

Hope for the Best…..Prepare for the Worst!

Telephone Alerts Available for Flooding Hazards

The War on Food Waste

Little Red School House Drive a Big Success!

A Herd of Folks at the Thurston County Fair

Making it in the Dry Years

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 Volcanic Eruption Can Happen Anytime.

Are you prepared?

The anniversary of the Mount Saint Helens eruption is a good reminder that we live in the shadow of a volcano. While Mount Rainier has not erupted for a long time, neither had Mount St. Helens before she rumbled back to life in March of 1980. Let’s take a look at some of the main hazards of volcanoes and how to prepare for them.

Pyroclastic Flows
High-speed avalanches of hot ash, rock fragments, and gas can move down the sides of a volcano during explosive eruptions or when the steep side of a growing lava dome collapses and breaks apart. These pyroclastic flows can be as hot as 1,500 °F and move at speeds of 100 to 150 miles per hour. Such flows tend to follow valleys and are capable of knocking down and burning everything in their paths. Lower-density pyroclastic flows, called pyroclastic surges, can easily overflow ridges hundreds of feet high.

Lahars


Mudflows or debris flows, composed mostly of volcanic materials on the flanks of a volcano, are called lahars. These flows of mud, rock, and water can rush down valleys and stream channels at speeds of 20 to 40 miles per hour and can travel more than 50 miles. Some lahars contain so much rock debris (60 to 90% by weight) that they look like fast-moving rivers of wet concrete. Close to their source, these flows are powerful enough to rip up and carry trees, houses, and huge boulders miles downstream. Farther downstream they entomb everything in their path in mud.

Historically, lahars have been one of the deadliest volcano hazards. They can occur both during an eruption and when a volcano is quiet. Large lahars are a potential hazard to many communities downstream from glacier-clad volcanoes, such as Mount Rainier.

What to do Before a Volcanic Eruption


Let’s assume you have emergency preparedness kits at your home and in your car. (You ARE ready to be on your own for at least three days, right?) You might want to add a pair of goggles and disposable breathing mask for each member of the family to your disaster supply kit because you live near a volcano. You should also stay away from active volcano sites once an announcement has been made by local authorities. Also, be ready to evacuate at a moment's notice.

If a Volcano Erupts Where You Live


  • Follow the evacuation order issued by authorities and evacuate immediately from the volcano area to avoid flying debris, hot gases, lateral blast, and lava flow.
  • Be aware of mudflows. The danger from a mudflow increases near stream channels and with prolonged heavy rains. Mudflows can move faster than you can walk or run. Look upstream before crossing a bridge, and do not cross the bridge if a mudflow is approaching.
  • Avoid river valleys and low-lying areas.
  • Remember to help your neighbors who may require special assistance - infants, elderly people, and people with disabilities.


Protection from Falling Ash
  • Listen to a battery-powered radio or television for the latest emergency information.
  • If you have a respiratory ailment, avoid contact with any amount of ash.
  • Wear long-sleeved shirts and long pants.
  • Use goggles and wear eyeglasses instead of contact lenses.
  • Use a dust mask or hold a damp cloth over your face to help with breathing.
  • Stay away from areas downwind from the volcano to avoid volcanic ash.
  • Stay indoors until the ash has settled unless there is a danger of the roof collapsing.
  • Close doors, windows, and all ventilation in the house (chimney vents, furnaces, air conditioners, fans, and other vents.
  • Clear heavy ash from flat or low-pitched roofs and rain gutters.
  • Avoid running car or truck engines. Driving can stir up volcanic ash that can clog engines, damage moving parts, and stall vehicles.
  • Avoid driving in heavy ash fall unless absolutely required. If you have to drive, keep speed down to 35 MPH or slower.


This article contains information from the U. S. Geological Survey Cascades Volcano Observatory. and the Federal Emergency Management Agency.

Photos courtesy of the U. S. Geological Survey.

By John Tennis

The dome rebuilding is underway. The dome rebuilding is underway.