DataSheet1_Three-Dimensional Tomography of Coseismic Ionospheric Disturbances Following the 2018 Palu Earthquake and Tsunami from GNSS Measurements.PDF

Preliminary research analyzed the Coseismic Ionospheric Disturbances (CIDs) of the strike-slip earthquake that occurred in Palu on September 28, 2018 (Mw = 7.5) and the materialization of a TEC anomaly with an amplitude of 0.4 TECU approximately 10–15 min later. The TEC anomaly amplitude is also affected by the magnitude of the earthquake moment; therefore, 3D analysis is needed to determine the spatial distribution of the ionospheric disturbances. This research aims to analyze the ionospheric disturbance of an earthquake in 3D using the Global Navigation Satellite System (GNSS) from the Geospatial Information Agency (BIG) or InaCORS stations spread over Sulawesi, Kalimantan, West Nusa Tenggara, East Nusa Tenggara, Bali, and Java with a 30 s sampling interval using GLONASS and GPS satellites. The checkerboard accuracy test was also carried out to evaluate the reliability of the 3D tomography model. The result showed that CIDs occur to the north and south of the epicenter around the equator, following the N-S Asymmetry theory. Furthermore, the tomography results indicate the presence of dominant and positive anomaly values at an altitude of 300–500 km. This follows the characteristics of variations in the ionosphere layer, where an altitude of 300–500 km is included in the F layer. The dominant anomaly at an altitude of 300 km is in accordance with the theory of the ionosphere’s height, which experiences maximum ionization at an altitude of ∼300 km (F layer) by Chapman’s profile. We also conducted preseismic studies of ionospheric anomalies before the earthquake as an additional analysis.

初步研究分析了2018年9月28日在Palu发生的（Mw = 7.5）走滑地震的地震同震电离层扰动（CIDs）以及约10-15分钟后出现的TEC异常（振幅为0.4 TECU）。TEC异常的振幅亦受地震矩的大小影响；因此，需要进行三维分析以确定电离层扰动的空间分布。本研究旨在利用全球导航卫星系统（GNSS）从地理信息局（BIG）或InaCORS站点，采用GLONASS和GPS卫星，以30秒的采样间隔对苏拉威西、加里曼丹、西努沙登加拉、东努沙登加拉、巴厘岛和爪哇等地区进行三维地震电离层扰动分析。此外，还进行了棋盘格精度测试，以评估三维层析成像模型的可靠性。结果表明，CIDs在赤道附近震中南北两侧发生，符合N-S非对称理论。进一步地，层析成像结果指示在300-500公里高度存在主要且正值异常。这与电离层层的特性相符，其中300-500公里的高度包含在F层中。300公里高度的主要异常与电离层高度理论相吻合，即在约300公里的高度（F层）通过Chapman分布达到最大电离。我们还对地震前电离层异常进行了震前研究，作为额外分析的补充。