| Abstrakt: |
Deep low‐frequency earthquakes (DLFE) are observed beneath volcanoes worldwide but are limited to island arc volcanoes, hotspot volcanoes, and rift zones. Here we show DLFEs in the Tengchong Volcano Field, southeast Tibet, located ∼300 km from the Indo‐Burma volcanic arc, by analyzing a 12‐year continuous seismic data set. The earthquakes were at a depth of ∼12 km, near the sidewall of the magma body detected by the magnetotelluric survey. The features of isotropic focal mechanism, episodic occurrence, and possible non‐power‐law scaling, with no detectable geodetic deformation, as well as the petrological signatures of the Holocene eruption product, suggest that the earthquakes were likely associated with the weak intermittent magma flows near the magma body. This finding may demonstrate the existence of unsteady magmatic processes in the margin of the Indo‐Eurasia collision zone, which could indicate unneglectable volcanic hazards, underestimated geothermal resources, and mineralization processes in similar regions. Plain Language Summary: Magmatic systems in the subduction arc, rift zone, and hotspot region are often active when magma stalls in the crust, indicative of unsteady magma dynamics and potential hazards. Holocene eruptions, present‐day structure anomaly, and geochemical signatures exist in some intra‐continent volcanos far away from the well‐predicted regions by plate tectonics. However, the magmatic systems there are thought to be relatively inactive. In this report, we show the first evidence of deep low‐frequency earthquakes occurring in the continental land on the edge of the Tibet Plateau, without any of the arc, hotspot, and rift volcanism involved. The observations' systematic characterization indicates weak but unsteady fluid flow currently occurring in this region. This finding demonstrates an unexpected behavior of the magmatic system in the continental collision zone, which may be underpredicted by the classic theory of plate tectonics on volcanism. Key Points: We report the discovery of deep low‐frequency earthquakes in the margin of the Tibet PlateauDeep origin, isotropic mechanism, low occurrence, and non‐power‐law scaling of the earthquakes are likely related to an unsteady fluid flowSeismic, petrological, and geochemical observations suggest the existence of juvenile magma flow beneath the Tengchong Volcanic Field [ABSTRACT FROM AUTHOR] |
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