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As part of the Acoustic Surveillance for Hazardous Eruptions project, two infrasound arrays were installed in northern and central Ecuador. The RIOE and LITE arrays were operational between 2006 and 2013, recording thousands of infrasound signals originating from eruptions of Tungurahua, El Reventador, and Sangay. We use Progressive Multi-Channel Correlation array processing together with hierarchical clustering to identify and associate impulsive infrasound signals with each volcano. Infrasound detections correspond to quasi-continuous activity of Sangay between mid 2006 and mid 2012, at least thirteen periods of activity of Tungurahua between 2006 and mid 2012, and strong signals from El Reventador in early 2008. We validate our detections using satellite observations from the MODIS (Moderate Resolution Imaging Spectroradiometer) volcano detection algorithm (MODVOLC) and independent eruption catalogs. For Sangay, we find a good agreement between our infrasound detections and MODVOLC triggers, whereas for El Reventador the agreement is fair. We attribute the fair correspondence at El Reventador to the low-temporal resolution of MODIS data and frequent cloud cover in the region that reduce satellite observational capability. Finally, our study highlights the benefits of infrasound arrays for monitoring volcanoes in Ecuador at regional distances, while further investigating the processes that limit volcanic infrasound detection.

More than 100 separate incidents of interactions between aircraft and volcanic ash were documented between 1973 and 2003. Incidents on international flight paths over remote areas have resulted in engine failures and significant damage and expense to commercial airlines. To protect aircraft from volcanic ash, pilots need rapid and reliable notification of ash- generating events. A global infrasound array network, consisting of the International Monitoring System (IMS) and other national networks, has demonstrated a capability for remote detection of Vulcanian to Plinian eruptions that can inject ash into commercial aircraft cruise altitudes (approximately 12 kilometers) near the tropopause. The identification of recurring sound signatures associated with high- altitude ash injection implies that acoustic remote sensing can improve the reliability and reduce the latency of these notifications.