The Magma plumbing system and seismo-tectonics of the Guatemala–Mexico triple junction as revealed by the seismicity of the Tacaná volcano before and after the 2017 <i>M</i>w8.2 Chiapas earthquake
Bibliographic record
Abstract
SUMMARY The triple junction between the North American, Caribbean and Cocos plates at the Guatemala–Mexico border is not well understood. It forms a broad region from around the active Tacaná volcano up to the Guatemala City graben. Tacaná is the westernmost active volcano of the Central American volcanic arc and is located at the intersection of four major active faults: the Polochic, Motagua, Jalpatagua and Tonalá faults. Using seismicity around the Tacaná volcano, we show that there is moderate to low tectonic seismic activity between the Guatemala City graben and the Tacaná volcano, possibly related to the ancient extremes of the Motagua and Jalpatagua faults. Therefore, we speculate that the triple junction would be located onshore, around the Tacaná volcano. We located earthquakes around the Tacaná volcano between January 2017 and October 2018, a period that includes the large Mw8.2 Tehuantepec (Chiapas) earthquake of 2017 September 8, located ∼190 km away. We identified four distinct types of seismicity, interpreted as having tectonic, hydrothermal, intermediate depth magmatic and deep magmatic origins. The tectonic seismicity occurred at depths between ∼5 and ∼30 km b.s.l., and may be associated with three faults around the Tacaná volcanic complex. These faults are oriented in NE–SW, aligned with the four Tacaná volcanic edifices; NW–SE, consistent with the Jalpatagua fault; and approximately EW, corresponding to the Motagua fault. The hydrothermal seismicity is observed at shallow depths, from the subsurface to about 2 km b.s.l., predominantly in the western sector of the Tacaná summit, and partially beneath the San Antonio volcano, an area known for intense hydrothermal activity. This seismicity is spatially related to the shallow portions of the same three faults described above. The intermediate depth magmatic seismicity is detected at depths between 5 and 12 km b.s.l. and is interpreted to be related to the presence of a shallow magma chamber beneath the Tacaná volcanic complex. Finally, the deep magmatic seismicity is located in the eastern part of the Tacaná, at depths ranging from 15 km to about 22 km b.s.l. This seismicity is interpreted to be due to a vertical dike intrusion that connects a deep magma reservoir located between 30 and 40 km depth, to the hypothesized shallower magma chamber associated with the intermediate depth seismicity.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".