Outdoor Warning System
Pierce County Department of Emergency Management (PCDEM) expanded the number and reach of the outdoor warning sirens in 2020. PCDEM has 42 sirens in the Puyallup River Valley and the Nisqually River Valley. These sirens are meant to get the attention of people who are outside so they know to get more information.
With the upgrades the sirens have more capabilities to notify people of emergencies. This includes using voice warnings in English and Spanish, flashing lights to reach additional vulnerable populations and verbal instructions based on the emergency.
Testing happens the first Monday of each month. The first test of the upgraded system was Monday, November 2, 2020. With this upgrade, the test sound the siren will make is similar to a Westminster chime on a clock. You can hear the tone and verbal instructions for the test below.
When there is an emergency, the system will use the "wail" siren to get people's attention. The strobe lights will flash and after the siren the verbal warning will also activate.
Click on the video to hear what the siren sounds like.
One of the natural hazards facing residents of Pierce County is volcanic activity from Mt. Rainier. Experts consider it one of the most dangerous volcanoes in the world, largely because of the threat of a lahar. A lahar is a large volcanic mudslide, stemming from snow and ice melt; given the sheer number and volume of glaciers on Mt Rainier, and proximity of residents to the mountain, the damage could be catastrophic.
The Puyallup River Valley is at greatest risk. Tens of thousands of people live in areas that may have as little as 40 minutes to as much as 3 hours to move to safety once a large lahar is detected. This robust system was originally created to notify people promptly and widely, they were in harm’s way and how to prepare and take protective actions.
In response to this hazard, PCDEM has worked closely with our partners to create an integrated lahar warning system. The Mt. Rainier Lahar Warning System consists of two separate components, operating in tandem: Acoustic Flow Monitors (AFM) and the All Hazard Alert Broadcast (AHAB) sirens. Residents will also receive warning via PCALERT and other alerting mechanisms.
There are currently five Acoustic Flow Monitor sites on both the Carbon and Puyallup Rivers, plus two radio repeaters. The United States Geological Survey (USGS), in coordination with PCDEM, has made plans to upgrade the Acoustic Flow Monitors (AFM) detection technology. The USGS is working on a multiyear project to enhance the system and create new sites called Lahar Monitoring Stations (LMS) with new software, more solar panels, and some cameras. The upgrade project will focus first on the Puyallup drainage. Both systems will run in tandem to ensure operability before the old AFMs are removed.
Acoustic Flow Monitors (AFM): An automated system detects lahar flows by using a network of small sensors called acoustic flow monitors (AFMs) embedded underground to measure ground vibrations made by passing lahars. Computer base stations located in the Washington State Emergency Operations Center (EOC) and South Sound 9-1-1 continuously analyze signals from the field stations. Upon detection of a lahar, the computer alerts the 24 hour emergency monitoring and notification centers, who then initiate the warning component of the system. Warning messages would trigger immediate, preplanned emergency response actions.
All Hazard Alert Broadcast (AHAB) Sirens: The siren component is one aspect of that pre-planned emergency response. When imminent danger threatens, the outdoor sirens will be activated. Citizens will be advised to evacuate the valley floor and head to higher ground. The sirens are made for outdoor warning and used to alert residents in the Puyallup River Valley of the need to evacuate due to a lahar or other volcanic event. The outdoor sirens are tested at noon on the first Monday of every month. The outdoor sirens chime during testing and a voice announcement follows in English and Spanish. During a real event, the outdoor sirens will continuously wail until the batteries die or they are destroyed.
PCEM works in partnership with the United States Geological Survey (USGS), the Pacific Northwest Seismic Network (PNSN), Washington Military Department’s Emergency Management Division, and South Sound 9-1-1 to monitor and operate the systems.
The AFM component was developed by the USGS in 1998 and is now maintained by PCEM, while the sirens are operated and maintained by PCEM.
The outdoor sirens have been placed throughout the Orting and Nisqually valleys in close partnership with communities including Orting, Puyallup, Sumner, Fife, and the Port of Tacoma. Other communities