![Figure 1. (a) Locations of broadband seismic stations. Red triangles represent stations with velocity-type strong-motion seismometers (Tokyo Keiki TSM-1). Each station indicated by a green triangle features either a Nanometrics Trillium 120 or Compact broadband seismometer. The rectangle indicates the area shown in Figures 1b-1d. (b) Centroid moment tensor mechanisms of the 2016 earthquake (M w 7.7) and aftershocks with M w > 4.5. Dots indicate source locations of aftershocks with magnitudes larger than 4.0. Contour lines with an interval of 0.4 m represent the slip distribution estimated by teleseismic waveform inversion (see Figure S3). (c) Interseismic plate coupling estimated by Chlieh et al. [2014]. (d) Source mechanism of the 1942 earthquake (M w 7.8) and epicenters of aftershocks (black circles) estimated by Mendoza and Dewey [1984] with quality A or B (epicenter errors within 20 km).](https://www.researchgate.net/profile/Patricia-Pedraza/publication/314070101/figure/fig1/AS:796681771679744@1566955144278/a-Locations-of-broadband-seismic-stations-Red-triangles-represent-stations-with_Q320.jpg)
![Figure 4. Comparison of the slip distribution of the 1906 earthquake with the main shocks and aftershocks of the 1958, 1979, and 2016 earthquakes. The slip areas of the 1906 earthquake are displayed by colored squares with slip magnitudes indicated by the color scale. Red contours represent the slip distribution of the 2016 earthquake. Source mechanisms colored red indicate those of the 2016 earthquake (M w 7.7) and its aftershocks. The pink source mechanism is the Global CMT solution of the 1979 earthquake (M w 8.1), and pink stars indicate the epicenters of the 1979 aftershocks. The source mechanism of the 1958 earthquake (M w 7.7) (green) is assumed to be the same as that of the 1979 earthquake, and green stars indicate the epicenters of the 1958 aftershocks. The epicenters of the 1979 and 1958 earthquakes are those estimated by Mendoza and Dewey [1984] with quality A or B. The black rectangle encloses the high interplate coupling patch (C5) corresponding to the source of the 1958 earthquake.](https://www.researchgate.net/profile/Patricia-Pedraza/publication/314070101/figure/fig2/AS:796681771708416@1566955144336/Comparison-of-the-slip-distribution-of-the-1906-earthquake-with-the-main-shocks-and_Q320.jpg)
February 2017
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A large earthquake (Mw 7.7) occurred on 16 April 2016 within the source region of the 1906 earthquake in the Ecuador-Colombia subduction zone. The 1906 event has been interpreted as a megathrust earthquake (Mw 8.8) that ruptured the source regions of smaller earthquakes in 1942, 1958, and 1979 in this subduction. Our seismic analysis indicated that the spatial distribution of the 2016 earthquake and its aftershocks correlated with patches of high interplate coupling strength and was similar to those of the 1942 earthquake and its aftershocks, suggesting that the 2016 and 1942 earthquakes ruptured the same asperity. Our analysis of tsunami waveforms of the 1906 event indicated Mw around 8.4 and showed that large slip occurred near the trench off the source regions of the above three historical and the 2016 earthquakes, suggesting that a depth-dependent complex rupture mode exists along this subduction zone.