Seismoacoustic Analysis of the 7 July 2011 Abadan, Turkmenistan, Explosions

Abstract

ABSTRACT On 7 July 2011, a series of accidental explosions occurred in the town of Abadan, Turkmenistan. The explosions were observed at local distances (11 and 23 km) at the International Monitoring System (IMS) seismic array, GEYT, and at the Central Asian Cross-border Network (CAREMON), seismic station, ASHT. A total of 30 individual seismic events could be identified. IMS infrasound arrays also observed these explosions at longer ranges, for example, from 1374 km (I31KZ, Kazakhstan) to 4307 km (I48TN, Tunisia). These local and long-range observations allow us to compare yields estimated from the seismic data, 0.05–45 tonnes (trinitrotoluene [TNT] equivalent; using P-wave and Rg amplitude relationships) to those estimated from the infrasound data, 4–90 tonnes (using the dominant period). Given the long propagation distances to the closest IMS infrasound arrays, the signal durations are long and individual events in the series cannot be identified in the infrasound signals. Comparison of the seismic and infrasonic yield estimates suggests that the infrasonic dominant periods are likely associated with the largest explosions in the series. In addition to the seismic arrivals observed locally, air-to-ground coupled waves exhibiting downward first motions consistent with an initial positive blast overpressure are also observed at both GEYT and ASHT. The peak-to-peak amplitude of the air-to-ground coupled waves increases with increasing yield, whereas the period of these signals is yield independent. These amplitude observations suggest that air-to-ground coupled arrivals could be better exploited within event analyses and provide a further constraint upon yield. Fully exploiting these events of opportunity, that have multiphenomenology observations, will help to further improve our understanding of how energy from near-surface explosions partitions into the ground and atmosphere and, therefore, improve our understanding of future events.