Engineering Characteristics of Earthquake Motions from the Pawnee and Cushing Earthquakes in Oklahoma

摘要

In 2016 two moderate earthquakes occurred in Oklahoma, the M 5.8 Pawnee earthquake and the M 5.0 Cushing earthquake. Strong ground shaking from these earthquakes was captured with seismometers and accelerometers across the state of Oklahoma, including 4 motions recorded within 10 km of the M 5.0 Cushing event. The motions recorded within 400 km are analyzed in terms of their engineering characteristics: peak ground acceleration, spectral acceleration, peak ground velocity, Arias intensity, mean period, and duration. The near-field recordings from the Cushing earthquake are particularly interesting, with peak ground accelerations as large as 0.25 to 0.6 g. However, these motions did not have significant energy at longer periods. The spectral accelerations at 1.0 s generally were only 5 to 20% of the PGA values, the PGV were between 7 and 10 cm/s, and the mean period between 0.1 and 0.15 s. Additionally, the durations were very short (1-2 s). At distances between 10 and 50 km, the motions were much smaller in intensity for both the Pawnee and Cushing events with PGA values between 0.003 and 0.06 g and PGV between 0.3 and 3 cm/s. However, the durations were much longer (10-20 s) than the near-field motions. These data indicate the unique characteristics of near-field motions from potentially induced earthquakes in Central and Eastern North America (large PGA, smaller PGV, short duration), which influences the potential for damage to be induced during these events.