Mapping of interplate coupling in the Kamchatka subduction zone from variations in the earthquake size distribution

The geometry of supposed coupling zones in the Kamchatka subduction zoneis determined by the earthquake size distribution based on earlier revealed relationship between its shape and rate of inelastic deformations. In the areas of higher aseismic slip, a break of linearity in earthquake size distribution is observed owing to the deficit of large earthquakes. Zones of higher coupling between the oceanic and continental plates are characterized by an excess of large earthquakes and an inverse bend in the earthquake size distribution. The mapping results of the bend value agree with the coupling zones distinguished from satellite geodetic data and inversion of marigrams.

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Mapping of Interplate Coupling in the Kamchatka Subduction Zone from Variations in the Earthquake Size Distribution

Doklady Earth Sciences ◽

10.1134/s1028334x19020077 ◽

2019 ◽

Vol 484 (2) ◽

pp. 173-176

Author(s):

I. A. Vorobieva ◽

A. A. Soloviev ◽

P. N. Shebalin

Keyword(s):

Size Distribution ◽

Subduction Zone ◽

Interplate Coupling ◽

Earthquake Size

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Repeating Earthquakes Along the Colombian Subduction Zone

Journal of Disaster Research ◽

10.20965/jdr.2020.p0645 ◽

2020 ◽

Vol 15 (5) ◽

pp. 645-654

Author(s):

Juan Carlos Bermúdez-Barrios ◽

◽

Hiroyuki Kumagai

Keyword(s):

Subduction Zone ◽

Threshold Value ◽

Waveform Data ◽

Repeating Earthquakes ◽

Seismic Waveform ◽

Interplate Coupling ◽

Short Period ◽

Tectonically Active ◽

Waveform Similarity ◽

Large Earthquakes

Colombia is tectonically active, and several large earthquakes have ruptured the Colombia-Ecuador subduction zone (CESZ) during the last century. Among them, the Colombia-Ecuador earthquake in 1906 (Mw 8.4) and the Tumaco earthquake in 1979 (Mw 8.3) generated destructive tsunamis. Therefore, it is important to characterize the seismic rupture processes and their relation with interplate coupling along the CESZ. We searched for repeating earthquakes by performing waveform similarity analysis. Cross correlation (CC) values were computed between earthquake pairs with hypocenter differences of less than 50 km that were located in the northern CESZ (1°–4°N) and that occurred from June 1993 to February 2018. We used broadband and short-period seismic waveform data from the Servicio Geológico Colombiano (SGC) seismic network. A CC threshold value of 0.90 was used to identify the waveform similarity and select repeating earthquakes. We found repeating earthquakes distributed near the trench and the coast. Our estimated repeating earthquakes near the trench suggest that the interplate coupling in this region is low. This is in clear constrast to the occurrence of a large slip in the 1906 Colombia-Ecuador earthquake along the trench in the southern part of the CESZ, and suggests that rupture modes are different between the northern and southern parts of CESZ near the trench.

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