Estimation of the Tsunami Source of the 1979 Great Tumaco Earthquake Using Tsunami Numerical Modeling


Abstract eng:
The 1979 Great Tumaco earthquake occurred on 12 December recorded as a surface-wave magnitude of Ms7.7, and moment magnitude Mw8.1 reported in the Harvard CMT Catalog. The epicenter was located 80 km southwest of Tumaco, offshore the Pacific coast of Colombia. This event generated a tsunami that killed more than 220 residents of San Juan island, 60 km north of Tumaco. According to eyewitnesses, few minutes after the event the sea withdrew from the shoreline, then, it returned 10 to 15 minutes later in a succession of three to four cycles of waves. The observed maximum inundation height at this area was approximately 2.5 m. In addition, due to the coseismic crustal subsidence of approximately 1.2 to 1.6 m, streets and houses were inundated over a meter of water depth. Within the framework of the project “Application of State of the Art Technologies to Strengthen Research and Response to Seismic, Volcanic and Tsunami Events, and Enhance Risk Management in Colombia” (JST-JICA SATREPS), the tsunami source model of the 1979 great Tumaco earthquake was estimated from tsunami waveform records and coseismic crustal deformation data. First, a rupture fault of 250 km by 100 km was assumed, and then, to estimate the slip distribution, we divided the tsunami source into 5 subfaults of 50 km by 100 km size. The focal mechanisms of these subfaults are taken from the Harvard CMT solution (strike=30, dip angle=16, and rake=118). We conducted linear tsunami waveform inversion to reproduce the tsunami source using the recorded tsunami wave at Esmeraldas tide gauge station in Ecuador, which is located approximately 75 km south from the epicenter, and three coastal subsidence point in Colombia. The inversion result showed a maximum slip of 2.9 m in the central area of the fault. The estimated seismic moment was calculated as 2.20x1021Nm (Mw=8.16). In addition, the maximum tsunami height estimated from the slip distribution reached up to 8.0 m near San Juan island.

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Conference Title:
Conference Title:
16th World Conference on Earthquake Engineering
Conference Venue:
Santiago (CL)
Conference Dates:
2017-01-09 / 2017-01-13
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Text je chráněný podle autorského zákona č. 121/2000 Sb.



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 Record created 2017-01-18, last modified 2017-01-18


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