Abstract Modeling and analysis of gravity and earthquake data of a critically dynamic northeastern region of India assumes a special significance for understanding the seismicity and geodynamics. In this paper, the relation between lateral heterogeneity of gravity interfaces with subsurface structures, and seismic characteristics of northeast India are studied in detail to understand the seismicity and dynamics of the region using Bouguer gravity, earthquake and magnetotelluric data. The modern scaled power spectral analysis of gravity data has brought out crustal lateral heterogeneity at a depth of 8.33 km, 19.73 km and 37.14 km that correlate well with 10 km upper crust, 20 km lower crust and a Moho at 28–42 km revealed by 1D seismic crustal velocity and tomography studies. The inferred crustal depths support thinner crust over uplifted Shillong Plateau and gradual increase of depths over subduction interface of Indo Burmese Range. 2D gravity modeling constrained by seismic velocity model and 3D Euler deconvolution technique along two specific E-W and three N-S regional gravity transects delineated three significant high density anomalous heterogeneous intrusive bodies presumably due to underplating beneath Shillong Plateau, Mikir Massif and Indo Burmese Range. Based on the seismicity and stress pattern analysis through seismic ‘b’-value variation, we infer that the study region exhibits compressive stress concentrations in the form of brittle deformation at shallow depths and weakening of lower crust by high density intrusive (mafic/Ultramafic) bodies of ductile nature which may cause intense seismicity besides the ongoing collision of north drifting Indian plate with Eurasia to the north and the eastern subduction interface of Indo Burmese Range. We also infer that the NE to NW trending V-shaped areas outlined north of Shillong plateau, south of Mikir massif and NE-SW trending thrust Belt of Schuppen exhibit aseismic nature and may be the future impounding seismic sources in this region.

中文翻译：

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重力模型和地震数据揭示了印度东北部西隆高原和印缅山脉下的高密度地壳侵入体

摘要 印度东北部临界动态重力和地震数据的建模和分析对于理解地震活动和地球动力学具有特殊意义。本文利用布格重力、地震和大地电磁数据详细研究了重力界面与地​​下结构的横向非均质性与印度东北部地震特征之间的关系，以了解该地区的地震活动和动力学。重力数据的现代标度功率谱分析表明，8.33 公里、19.73 公里和 37.14 公里深度的地壳横向非均质性与 10 公里上地壳、20 公里下地壳和 28-42 公里处的莫霍面密切相关。一维地震地壳速度和层析成像研究。推断的地壳深度支持隆起的西隆高原上较薄的地壳和印缅山脉俯冲界面上的深度逐渐增加。受地震速度模型和 3D 欧拉反褶积技术约束的 2D 重力建模沿两个特定的 EW 和三个 NS 区域重力断面描绘了三个显着的高密度异常非均质侵入体，推测可能是由于西隆高原、Mikir 地块和印缅山脉下方的底板。基于通过地震“b”值变化进行的地震活动性和应力模式分析，我们推断，研究区表现出压应力集中，表现为浅层脆性变形和下地壳弱化的高密度侵入性（镁铁质/超镁铁质）韧性性质的物体，除了北漂印度洋的持续碰撞外，这可能导致强烈的地震活动。板块与欧亚大陆以北和印缅山脉东部俯冲界面。我们还推断，西隆高原以北、Mikir 地块以南和 Schuppen NE-SW 向冲断带所勾画的 NE 到 NW 走向的 V 形区域具有抗震性质，可能是该地区未来的蓄水震源。