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- Title
Active Crustal Deformation in the Trans‐Mexican Volcanic Belt as Evidenced by Historical Earthquakes During the Last 450 Years.
- Authors
Suárez, Gerardo; Caballero‐Jiménez, Gema V.; Novelo‐Casanova, David A.
- Abstract
The Trans‐Mexican Volcanic Belt (TMVB) is oblique to the subduction zone. Background seismicity is very low. Nevertheless, two large instrumental earthquakes were recorded: the 1912 Acambay (Mw 6.9) and the 1920 Jalapa (Mw 6.4) earthquakes. Macroseismic data were systematically searched for crustal earthquakes on the TMVB contained in historical accounts. The macroseismic reports were inverted for the best fitting magnitude and epicenter. The western end of the TMVB shows the highest level of seismic activity. An earthquake is reported in 1568 (Mw 7.2 ± 0.2) and a second large event took place in 1875 (Mw 7.0 ± 0.2). Two other earthquakes are reported in the western TMVB in 1611 and 1749 (Mw 6.4). The 1858 earthquake (Mw 7.6 ± 0.3), in the central TMVB occurred on faults located to the west of the 1912 Acambay event. The eastern TMVB is less active. An earthquake in 1575 (Mw 5.7) occurred east of the city of Puebla. The 1887 (Mw 6.2 ± 0.2) and the 1920 Jalapa earthquakes are the larger events in this region. The seismicity observed from the instrumental and historical seismicity catalogs show that active tectonic deformation occurs throughout the TMVB and that it is not confined to specific regions where instrumental earthquakes have been located and active faults mapped. The number of large earthquakes in the TMVB, suggest unique large‐scale deformation of this complex volcanic belt. The presence of large earthquakes in this tectonic province, where 40% of the population of Mexico live, underlines the importance of reevaluating hazard in this densely populated region. Plain Language Summary: The subduction of an oceanic plate results in the creation of a volcanic arc that is normally parallel to the coastline, where the subduction process takes place. In the case of the Trans‐Mexican Volcanic Belt (TMVB), its orientation is unique: It is oblique to the subduction zone to the south. Also, many active geological faults are distributed throughout the volcanic belt. The presence of these faults suggests that the TMVB is geologically active and under continuous deformation, albeit at a slow rate. Earthquakes are rarely recorded in the TMVB. However, in the last 500 years of written history, there is clear evidence of very large earthquakes that occurred on these faults. Some of these earthquakes are apparently as large as magnitude 7.3. During the past five centuries, at least seven earthquakes larger than magnitude 6.5 have taken place in these shallow geological faults in the crust of the TMVB. The presence of these earthquakes is evidence that the TMVB is under extension, in a manner which is not observed in other volcanic arcs. These earthquakes also occur near the more important population centers, posing an important seismic hazard that frequently is not taken into account. Key Points: The magnitude and epicentral locations of the more important historical earthquakes are determined inverting the macroseismic data or estimated based on the historical dataIt is shown that the TMVB is under active tectonic deformation and moderate‐sized earthquakes occur on several mapped active faultsSome earthquakes have occurred in the past on the TMVB in areas where no mapped faults exist, showing that the tectonic deformation extends throughout the volcanic belt
- Publication
Tectonics, 2019, Vol 38, Issue 10, p3544
- ISSN
0278-7407
- Publication type
Article
- DOI
10.1029/2019TC005601