The Mount Rainier Volcano Lahar Warning System consists of two separate components, operating in tandem: Acoustic Flow Monitors (AFM) and the All Hazard Alert Broadcast (AHAB) sirens. The AFM system was developed by the United States Geological Survey (USGS) in 1998 and is now maintained by Pierce County Emergency Management. The purpose of the warning system is to assist in the evacuation of residents in the river valleys around Mount Rainier, a volcano in Washington, in the event of a lahar. Pierce County works in partnership with the 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 system.
Mount Rainier is an active volcano in Washington. It has previously buried sections of the surrounding river valleys in a volcanic mudflow, called a lahar. 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 three hours to move to safety once a large lahar is detected, so the system is robust, warnings are disseminated promptly and widely, and people in harm's way are taught how to respond to the warnings and take protective actions. [1]
Geologists consider Mount Rainier the most dangerous mountain in the United States, [2] and the USGS has estimated there is a one-in-seven chance of a catastrophic lahar at Mount Rainier occurring in the next 75 years. [3]
Pierce County Emergency Management and the USGS have made plans to upgrade the AFM detection technology, expand the siren component, and are now working on a multiyear project to enhance the system. [4]
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) continuously analyze signals from the field stations. Upon detection of a lahar, the computer alerts local 24–hour emergency monitoring and notification centers, who initiate the warning component of the system. Warning messages would trigger immediate, preplanned emergency-response actions. [5]
All Hazard Alert Broadcast (AHAB) Sirens: The Mount Rainier Lahar Siren project is part of an overall emergency communications system for Pierce County. The focus for the sirens is to warn the residents in the Puyallup River Valley of the need to evacuate due to a volcanic disaster from the Mount Rainier Volcano. Over 40 Federal Signal Modulator sirens are strategically placed through the valley. When imminent volcanic danger threatens, the sirens will be activated, utilizing the emergency “wailing” tone. Citizens will be advised to evacuate the valley floor and head to higher ground by vehicle or foot. The outdoor lahar warning sirens are tested at noon on the first Monday of months January-September, November-December, using the “Westminster Chime” tone for eight seconds followed by a voice announcement to ensure the sirens are working. Every October on the first Monday at Noon, the emergency warbling “wail” tone is tested for approximately five minutes. [6] During a real volcanic event or other disaster, the sirens will continuously “wail” in 5 minute increments to warn residents and tourists to evacuate. They will continue to wail until the batteries die or the sirens themselves are destroyed by the lahar. [7]
Orting is a city in Pierce County, Washington, United States. The population was 9,041 at the 2020 census.
A lahar is a violent type of mudflow or debris flow composed of a slurry of pyroclastic material, rocky debris and water. The material flows down from a volcano, typically along a river valley.
Nevado del Ruiz, also known as La Mesa de Herveo is a volcano on the border of the departments of Caldas and Tolima in Colombia, about 129 km (80 mi) west of the capital city Bogotá. It is a stratovolcano composed of many layers of lava alternating with hardened volcanic ash and other pyroclastic rocks. Volcanic activity at Nevado del Ruiz began about two million years ago, since the Early Pleistocene or Late Pliocene, with three major eruptive periods. The current volcanic cone formed during the present eruptive period, which began 150,000 years ago.
Glacier Peak or Dakobed is the most isolated of the five major stratovolcanoes of the Cascade Volcanic Arc in the U.S state of Washington. Located in the Glacier Peak Wilderness in Mount Baker–Snoqualmie National Forest, the volcano is visible from the west in Seattle, and from the north in the higher areas of eastern suburbs of Vancouver such as Coquitlam, New Westminster and Port Coquitlam. The volcano is the fourth tallest peak in Washington state, and not as much is known about it compared to other volcanoes in the area. Local Native Americans have recognized Glacier Peak and other Washington volcanoes in their histories and stories. When American explorers reached the region, they learned basic information about surrounding landforms, but did not initially understand that Glacier Peak was a volcano. Positioned in Snohomish County, the volcano is only 70 miles (110 km) northeast of downtown Seattle. From locations in northern Seattle and northward, Glacier Peak is closer than the more famous Mount Rainier (Tahoma), but as Glacier Peak is set farther into the Cascades and almost 4,000 feet (1,200 m) shorter, it is much less noticeable than Mount Rainier.
The Puyallup River is a river in the U.S. state of Washington. About 45 miles (72 km) long, it is formed by glaciers on the west side of Mount Rainier. It flows generally northwest, emptying into Commencement Bay, part of Puget Sound. The river and its tributaries drain an area of about 948 square miles (2,460 km2) in Pierce County and southern King County.
The Pacific Northwest Seismic Network, or PNSN, collects and studies ground motions from about 400 seismometers in the U.S. states of Oregon and Washington. PNSN monitors volcanic and tectonic activity, gives advice and information to the public and policy makers, and works to mitigate earthquake hazard.
The Volcano Disaster Assistance Program (VDAP) was developed by the U.S. Geological Survey and the United States Agency for International Development's Office of U.S. Foreign Disaster Assistance after the eruption of Nevado del Ruiz (Colombia) in 1985. The volcanic eruption melted a glacier triggering a lahar that killed 25,000 people. It was determined that increased monitoring and enhanced communications between scientists and civil authorities would make it easier to evacuate local populations and save lives. Today the program responds to volcanic crises around the world. The aim of the program is to assist in saving lives and property, to reduce economic losses, and to prevent a natural hazard becoming a natural disaster. VDAP staff members are based at the USGS Cascades Volcano Observatory, in Vancouver, Washington. VDAP channels its energy into four main activities: response to natural disaster, capacity building, training, and volcanological research.
Mount Rinjani is an active volcano in Indonesia on the island of Lombok. Administratively the mountain is in the Regency of North Lombok, West Nusa Tenggara. It rises to 3,726 metres (12,224 ft), making it the second highest volcano in Indonesia. It is also the highest point in the Indonesian province of West Nusa Tenggara.
The Armero tragedy occurred following the eruption of the Nevado del Ruiz stratovolcano in Tolima, Colombia, on November 13, 1985. The volcano's eruption after 69 years of dormancy caught nearby towns unaware, even though volcanological organizations had warned the government to evacuate the area after they detected volcanic activity two months earlier.
The Carbon River is a river in the U.S. state of Washington. It flows about 30 miles (48 km) from its source, the Carbon Glacier on Mount Rainier, to join the Puyallup River at Orting.
Prediction of volcanic activity, or volcanic eruption forecasting, is an interdisciplinary monitoring and research effort to predict the time and severity of a volcano's eruption. Of particular importance is the prediction of hazardous eruptions that could lead to catastrophic loss of life, property, and disruption of human activities.
The Cascade Volcanoes are a number of volcanoes in a volcanic arc in western North America, extending from southwestern British Columbia through Washington and Oregon to Northern California, a distance of well over 700 miles (1,100 km). The arc formed due to subduction along the Cascadia subduction zone. Although taking its name from the Cascade Range, this term is a geologic grouping rather than a geographic one, and the Cascade Volcanoes extend north into the Coast Mountains, past the Fraser River which is the northward limit of the Cascade Range proper.
The Silverthrone Caldera is a potentially active caldera complex in southwestern British Columbia, Canada, located over 350 kilometres (220 mi) northwest of the city of Vancouver and about 50 kilometres (31 mi) west of Mount Waddington in the Pacific Ranges of the Coast Mountains. The caldera is one of the largest of the few calderas in western Canada, measuring about 30 kilometres (19 mi) long (north-south) and 20 kilometres (12 mi) wide (east-west). Mount Silverthrone, an eroded lava dome on the caldera's northern flank that is 2,864 metres (9,396 ft) high, may be the highest volcano in Canada.
Mount Rainier, also known as Tahoma, is a large active stratovolcano in the Cascade Range of the Pacific Northwest in the United States. The mountain is located in Mount Rainier National Park about 59 miles (95 km) south-southeast of Seattle. With a summit elevation of 14,417 ft (4,394 m), it is the highest mountain in the U.S. state of Washington and the Cascade Range, the most topographically prominent mountain in the contiguous United States, and the tallest in the Cascade Volcanic Arc.
The 1991 eruption of Mount Pinatubo in the Philippines' Luzon Volcanic Arc was the second-largest volcanic eruption of the 20th century, behind only the 1912 eruption of Novarupta in Alaska. Eruptive activity began on April 2 as a series of phreatic explosions from a fissure that opened on the north side of Mount Pinatubo. Seismographs were set up and began monitoring the volcano for earthquakes. In late May, the number of seismic events under the volcano fluctuated from day-to-day. Beginning June 6, a swarm of progressively shallower earthquakes accompanied by inflationary tilt on the upper east flank of the mountain, culminated in the extrusion of a small lava dome.
A volcanic hazard is the probability a volcanic eruption or related geophysical event will occur in a given geographic area and within a specified window of time. The risk that can be associated with a volcanic hazard depends on the proximity and vulnerability of an asset or a population of people near to where a volcanic event might occur.
Alderton is a census-designated place (CDP) in Pierce County, Washington, United States. The population was 2,893 at the 2010 census. The community is located in the Puyallup River Valley between the cities of Sumner and Orting.
The Bridge for Kids is a proposed bridge across the Carbon River in Orting, Washington, about a mile upstream of where it joins the Puyallup River. It would provide an emergency evacuation route for school children to escape a future lahar flow from Mount Rainier, consisting of an up to 10-meter (33 ft) high flood of mud, rock and boulders. As of 2016, the $40 million bridge was still in the planning phase.
The Osceola Mudflow, also known as the Osceola Lahar, was a debris flow and lahar in the U.S. state of Washington that descended from the summit and northeast slope of Mount Rainier, a volcano in the Cascade Range during a period of eruptions about 5,600 years ago. It traveled down the west and main forks of the White River, passed the location of present-day Enumclaw then reached Puget Sound in several areas, including near the present day sites of Tacoma and Auburn.
The National Volcano Early Warning and Monitoring System is a U.S. federal program within the U.S. Geological Survey for monitoring volcano activity and providing early warning to threatened areas. It was authorized by the John D. Dingell, Jr. Conservation, Management, and Recreation Act on March 12, 2019.