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Monitoring Volcanic Eruptions with a Wireless Sensor Network
Geoffrey Werner-Allen∗ , Jeff Johnson† , Mario Ruiz‡ , Jonathan Lees‡ , and Matt Welsh∗
University {werner, mdw}@eecs.harvard.edu † University of New Hampshire jeff.johnson@unh.edu ‡ University of North Carolina {mruiz, leesj}@email.unc.edu
∗ Harvard
Abstract— This paper describes our experiences using a wireless sensor network to monitor volcanic eruptions with low-frequency acoustic sensors. We developed a wireless sensor array and deployed it in July 2004 at Volc´ n a Tungurahua, an active volcano in central Ecuador. The network collected infrasonic (low-frequency acoustic) signals at 102 Hz, transmitting data over a 9 km wireless link to a remote base station. During the deployment, we collected over 54 hours of continuous data which included at least 9 large explosions. Nodes were time-synchronized using a separate GPS receiver, and our data was later correlated with that acquired at a nearby wired sensor array. In addition to continuous sampling, we have developed a distributed event detector that automatically triggers data transmission when a well-correlated signal is received by multiple nodes. We evaluate this approach in terms of reduced energy and bandwidth usage, as well as accuracy of infrasonic signal detection.
I. I NTRODUCTION Wireless sensor networks have the potential to greatly benefit studies of volcanic activity. Volcanologists currently use wired arrays of sensors, such as seismometers and acoustic microphones, to monitor volcanic eruptions. These sensor arrays are used to determine the source mechanism and location of an earthquake or explosion, study the interior structure of the volcano, and differentiate true eruptions from noise or other signals (e.g., mining activity) not of volcanological interest. A typical campaign-type study will involve placement of one or more stations on various sites around a volcano. Each station typically consists of a few (less than five)
Geoffrey Werner-Allen∗ , Jeff Johnson† , Mario Ruiz‡ , Jonathan Lees‡ , and Matt Welsh∗
University {werner, mdw}@eecs.harvard.edu † University of New Hampshire jeff.johnson@unh.edu ‡ University of North Carolina {mruiz, leesj}@email.unc.edu
∗ Harvard
Abstract— This paper describes our experiences using a wireless sensor network to monitor volcanic eruptions with low-frequency acoustic sensors. We developed a wireless sensor array and deployed it in July 2004 at Volc´ n a Tungurahua, an active volcano in central Ecuador. The network collected infrasonic (low-frequency acoustic) signals at 102 Hz, transmitting data over a 9 km wireless link to a remote base station. During the deployment, we collected over 54 hours of continuous data which included at least 9 large explosions. Nodes were time-synchronized using a separate GPS receiver, and our data was later correlated with that acquired at a nearby wired sensor array. In addition to continuous sampling, we have developed a distributed event detector that automatically triggers data transmission when a well-correlated signal is received by multiple nodes. We evaluate this approach in terms of reduced energy and bandwidth usage, as well as accuracy of infrasonic signal detection.
I. I NTRODUCTION Wireless sensor networks have the potential to greatly benefit studies of volcanic activity. Volcanologists currently use wired arrays of sensors, such as seismometers and acoustic microphones, to monitor volcanic eruptions. These sensor arrays are used to determine the source mechanism and location of an earthquake or explosion, study the interior structure of the volcano, and differentiate true eruptions from noise or other signals (e.g., mining activity) not of volcanological interest. A typical campaign-type study will involve placement of one or more stations on various sites around a volcano. Each station typically consists of a few (less than five)