Introduction to Volcanoes 1

INTRODUCTION TO VOLCANOES 1 Introduction Active volcanoes dominate the sky- short-lived, volcanoes dot the land- line in many parts of the Pacific scape in southwest Washington and Northwest. These familiar snow-clad northwest Oregon, the youngest of peaks are part of a 1,000 mile-long them a few thousand years old. These chain of volcanoes, the Cascade individual volcanoes probably won’t volcanic arc, which extends from erupt again; rather, new volcanoes northern California to southern will form among them and add to the British Columbia. This guide focuses broad regional volcanic fields that on the five in Washington State lie among the major volcanoes from (Mount Baker, Glacier Peak, Mount Mount Rainier southward. Rainier, Mount St. Helens, and Mount Adams) and Mount Hood in northern Water and volcanoes — Oregon that are long-lived volcanoes, a dangerous combination having erupted recurrently for hun- Large parts of Washington’s Cascade dreds of thousands of years. All of volcanoes are covered with perma- these volcanoes have erupted in the nent snow and ice that pose a special recent geologic past and will erupt hazard during volcanic eruptions. again in the future. In 1980 Mount Even small eruptions can melt a St. Helens vividly demonstrated the sufficient amount of snow and ice power that Cascade volcanoes can to trigger lahars that can travel tens unleash when they do erupt. of miles beyond the flanks of the volcano into populated valleys. For Frequency of eruptions years after an eruption, erosion of in the Cascades deposits can cause increased sedi- Seven major, long-lived volcanoes ment deposition that clogs channels, in the Cascades, including three disrupts aquatic ecosystems, and in Washington and Mount Hood in worsens flooding. northern Oregon, have erupted since early pioneers arrived in the region. Note to Media Many of those eruptions would have This guidebook supplies back- caused considerable property dam- ground information about volcano age, and potentially loss of life, had hazards and an overview of the they happened today. Based on the notification process used to send frequencies of eruptions during the volcano alerts to emergency and past 4,000 years, we expect that sev- land managers, the media, emer- eral eruptions will occur per century. gency broadcasters, and the public. Each eruptive episode is likely to last It includes background information months or years to perhaps a decade about volcanic hazards expectable at or more. In addition to the major vol- Washington volcanoes, maps show- canoes, hundreds of small, typically ISSUE UPDATE: JUNE 2010 2 MEDIA GUIDEBOOK FOR NATURAL HAZARDS IN WASHINGTON ing areas most susceptible to these Signs of unrest and eruption hazards, a volcano warning flow trigger alerts chart that shows how information Scientists cannot forecast when a is sent to emergency management volcano will become active, although and local media, and a list of pub- once signs of unrest are noted and lished resources and specialists sufficient measurements are made, who can provide credible volcano they may be able to estimate the like- information. lihood of an eruption and sometimes its size and character. Volcanoes typ- Communicating hazards ically show signs of unrest, such as information increased earthquakes, emission of The US Geological Survey’s Cascades volcanic gases, and subtle ground Volcano Observatory (USGS-CVO) movement, days to months in issues alert-level notifications and advance of an eruption. Earthquake information statements, and, when- activity is often the first indicator of ever possible, specific forecasts volcanic unrest. The USGS, in coor- regarding eruptions and their poten- dination with the Pacific Northwest tial impacts. This process includes Seismic Network (PNSN) at the color codes for aviation hazards. University of Washington, monitors Volcano alert levels and the avia- seismic unrest in the Washington tion color codes are described in the Cascades. Volcano Alert Notification System section (refer to Notification System Earthquake swarms at tab section). Scientists notify emer- Cascade volcanoes gency-management officials and the Swarms of small earthquakes that go media using the process described on for up to several days are common in the Volcano Warning Flow Chart features at many volcanoes. The vast (see Flow Chart tab). At all times, the majority of these earthquake swarms USGS-CVO provides information do not lead directly to eruptive activ- about volcanoes and volcano hazards ity but are signs of a still functioning to public officials, land-use planners, volcano. Recent earthquake swarms emergency response organizations, shook Mount Rainier in 2002, 2004, Federal Aviation Administration, 2007, and 2009, for example. National Weather Service, Federal Emergency Management Agency (FEMA), and other federal agencies, the news media, schools, and the general public. ISSUE UPDATE: JUNE 2010 INTRODUCTION TO VOLCANOES 3 Volcano emergencies are times Who can be affected? of great uncertainty • Severe hazards can affect areas on Restless volcanoes can challenge a volcano’s flanks rapidly. people at risk more than most other natural hazards because they pres- • Communities in valleys that lead ent multiple uncertainties about from a volcano are at risk from when eruptive or other hazardous lahars (volcanic mudflows). People activity will begin, what its charac- at risk must know how to reach ter and magnitude will be, how long high ground off the valley floor it will last, and who will be affected. so that they can escape before the Unlike floods and earthquakes, vol- lahar’s arrival. canic eruptions are seldom singular • Downwind, volcanic ash fall can events; activity is often prolonged be a nuisance or significant threat, over a period of weeks to years. depending on how much ash falls. Sometimes, volcanic unrest does not Shelter in place unless also at risk culminate in an eruption. But, even from a lahar. without eruptions, the uncertainty associated with volcanic unrest can Who’s taking action? cause a major psychological and eco- • For your peace of mind, and so nomic impact on the population. that you can be forewarned, scientists use ground-based and remote Principal Messages for the Public sensing instruments to track vol- What can happen? canic activity. • With virtual certainty, Cascade • For your safety, public officials volcanoes will erupt again, even and scientists assemble and within our lifetimes. practice volcano emergency coor- dination plans. • Volcanoes provide us with warning signs of reawakening days to What you can do: months in advance of an eruption, • People who are knowledgeable and but exact timing and size can only prepared can survive in greater be estimated. safety and comfort and with con- • A common scenario is the erup- fidence during the next volcanic tion of volcanic ash, and later eruption. Your family will count melting snow and ice, which can on you to follow these measures. create lahars (volcanic mudflows). Lahars can surge off a restless or erupting volcano and flow down valleys for tens of miles. ISSUE UPDATE: FEBRUARY 2013 4 MEDIA GUIDEBOOK FOR NATURAL HAZARDS IN WASHINGTON • Learn—Your family, school and business will have a better oppor- tunity to survive safely or recover quickly if they learn now about the location of volcano hazard zones. • Inquire— Inquiring about current volcano conditions, community evacuation plans, and then obey- ing officials can help your family or business survive with less dis- ruption during an eruption. • Prepare—Preparing your home with extra supplies and an emergency communication plan may reduce losses and help your family will recover from future volcanic eruptions. ISSUE UPDATE: FEBRUARY 2013 VOLCANO WARNING FLOW CHART 1 Volcano Warning Flow Chart HOW THE VOLCANO WARNING SYSTEM WORKS USGS Cascades Volcano Alert NWS sends Volcano EAS Volcano Level Message Message Observatory State EOC and (Vancouver WA) Local jurisdictions and land managers and Broadcasters and General distribution to Volcano Aviation public via NOAA Weather Color Code Radio and Internet Message State EOC sends (via EAS) Washington DC, EMD / COUNTY VOLCANO WARNING VAAC To: Broadcasters (via EAS) Pre-scripted Message NWS Local jurisdictions FAA Citizens (via NOAA Weather Radio) AHAB Sirens (Pierce County activates for Mount Rainier) State EOC sends (via EAS) Pre-scripted Message COUNTY EVACUATION This message sent by State EOC at request of County To: Broadcasters via EAS Local jurisdictions Citizens (via NOAA Weather Radio) AHAB Sirens (Pierce County activates for Mount Rainier) USGS US Geological Survey Washington State EOC: State Emergency Operation Center Military NWS: National Weather Service Department AHAB: All Hazards Alert Broadcast Emergency EAS: Emergency Alert System Management VAAC: Volcano Ash Advisory Center Division FAA: Federal Aviation Administration ISSUE UPDATE: JUNE 2010 2 MEDIA GUIDEBOOK FOR NATURAL HAZARDS IN WASHINGTON ISSUE UPDATE: JUNE 2010 VOLCANO EXPERT CONTACTS 1 Volcano Expert Contacts US Geological Survey-Cascades Volcano Observatory 1300 SE Cardinal Court Vancouver, WA 98683 Tel: 360-993-8973 Fax: 360-993-8980 E-mail: [email protected] Website: http://vulcan.wr.usgs.gov/ Pacific Northwest Seismic Network (PNSN) Seismology Lab University of Washington Dept. of Earth and Space Sciences Box 351310 Seattle, WA 98195-1310 Tel: 206-543-7010 Fax: 206-685-5788 E-mail: [email protected] Website: http://www.pnsn.org/ Washington Emergency Management Division Washington Military Department Emergency Management Division Building 20, MS TA-20 Camp Murray, WA 98430-5112 Tel: 1-800-688-8955 Main Tel: 1-800-562-6108, or 253-512-7000 Website: http://www.emd.wa.gov/ ISSUE UPDATE: JUNE 2010 2 MEDIA GUIDEBOOK FOR NATURAL HAZARDS IN WASHINGTON ISSUE UPDATE: JUNE 2010 VOLCANOE ALERT NOTIFICATION SYSTEM 1 Volcano Alert Notification System The USGS and its partners keep watch ground and aviation differ substan- over volcanoes within the United tially. In these cases, the Volcano Alert States (U.S.). The USGS is by law Level and Aviation Color Code will mandated to issue notifications re- move independently.

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