Optimum sea surface displacement and fault slip distribution of the 2017 Tehuantepec earthquake (Mw 8.2) in Mexico estimated from tsunami waveforms

Key Points:

  1. Tsunami waveforms resolve the optimum sea surface displacement with maximum sea surface uplift of 0.5 m and subsidence of 0.8 m.
  2. Large fault slip (3 – 6 m) located at depths between 30 – 90 km is estimated from the optimum sea surface displacement.
  3. Large tsunami amplitudes up to 2.5 m due to edge waves are estimated inside and around a lagoon between Salina Cruz and Puerto Chiapas.

 

Abstract

The 2017 Tehuantepec earthquake (Mw 8.2) was the first great normal fault event ever instrumentally recorded to occur in the Middle America Trench. The earthquake generated a tsunami with an amplitude of 1.8 m (height=3.5 m) in Puerto Chiapas, Mexico. Tsunami waveforms recorded at coastal tide gauges and offshore buoy stations were used to estimate the optimum sea surface displacement without assuming any fault. Our optimum sea surface displacement model indicated that the maximum uplift of 0.5 m is located near the trench and the maximum subsidence of 0.8 m on the coastal side near the epicenter. We then estimated the fault slip distribution that can best explain the optimum sea surface displacement assuming ten different fault geometries.  The best model suggests that a compact region of large slip (3 – 6 m) extends from a depth of 30 km to 90 km, centered at a depth of 60 km.

Keywords: the 2017 Tehuantepec earthquake, tsunami waveform inversion, optimum sea surface displacement, fault slip distribution, tsunami simulation.

See manuscript here

The 2017 Mexico Tsunami – GRL

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