17:15 〜 18:45
[STT35-P02] Three-dimensional displacement field associated with the 1 Jan. 2024 Noto Peninsula earthquake obtained from SAR pixel offset analysis
The Noto Peninsula has been known to be persistently uplifting since the early to middle Pleistocene (Ota and Hirakawa, 1979) with a fast rate of ~1m/kyr. Moreover, series of marine terraces preserved on the peninsula exhibit southward tilting with a small component of eastward tilting, indicating maximum uplift rates along the northwestern and northern coast of the peninsula.
A Mw 7.5 earthquake occurred beneath the Noto Peninsula on 1 Jan 2024. We derived the three-dimensional displacement field associated with the earthquake using the pixel offset analysis of the SAR images acquired by the Japanese ALOS-2 satellite. In this presentation, we report the derivation method of the displacement and discuss the observed basic features.
In the pixel offset analysis, we directly measure the distortion in the SAR image acquired after the earthquake with reference to the image acquired before the earthquake and convert it to the deformation in the physical dimension. We first conducted the pixel offset analysis on four pairs of SAR images to obtain the coseismic displacements in the range (line-of-sight) and azimuth (satellite-flying horizontal) directions from each of the four different pairs. Next, we compared each set of the obtained displacements to the coseismic GNSS displacements calculated from the F5 solution of the GENOET network of the Geospatial Authority of Japan, and corrected for a bias in each SAR-derived displacement data set. The data sets having significant discrepancy with the GNSS displacements were discarded at this stage. We finally decomposed the bias-corrected displacement data sets recording different components into the EW, NS and UD components.
The obtained displacement field is characterized by 1) significant uplift along the northern coast of the peninsula, with global and local maxima on the western and eastern areas, respectively, 2) westward movement of the northern part (latitude 37.1°N or higher) of the peninsula, and 3) the undulation of northward and southward displacements on the northeastern part of the peninsula. It is inferred that the first and second observed features mostly result from the oblique thrust motion of the main fault rupture, whereas the third one results from mountain slope sliding. The coseismic displacement field is remarkably consistent with the geomorphological features, indicating that the repeat of the 2024-type earthquakes is one of the main drivers of the landscape formation of the peninsula.
(Acknowledgements) SAR images were provided from JAXA through the Earthquake Working Group coordinated by the Geospatial Information Authority of Japan and JAXA. SAR pixel offset analysis was conducted using the ISCE software. We used the GEONET F5 products of the Geospatial Spatial Authority of Japan.
(Figure caption) Three-dimensional displacements obtained from the SAR pixel offset analysis and correction using the GNSS coseismic displacements. Color in the filled circles show the GNSS displacements.
A Mw 7.5 earthquake occurred beneath the Noto Peninsula on 1 Jan 2024. We derived the three-dimensional displacement field associated with the earthquake using the pixel offset analysis of the SAR images acquired by the Japanese ALOS-2 satellite. In this presentation, we report the derivation method of the displacement and discuss the observed basic features.
In the pixel offset analysis, we directly measure the distortion in the SAR image acquired after the earthquake with reference to the image acquired before the earthquake and convert it to the deformation in the physical dimension. We first conducted the pixel offset analysis on four pairs of SAR images to obtain the coseismic displacements in the range (line-of-sight) and azimuth (satellite-flying horizontal) directions from each of the four different pairs. Next, we compared each set of the obtained displacements to the coseismic GNSS displacements calculated from the F5 solution of the GENOET network of the Geospatial Authority of Japan, and corrected for a bias in each SAR-derived displacement data set. The data sets having significant discrepancy with the GNSS displacements were discarded at this stage. We finally decomposed the bias-corrected displacement data sets recording different components into the EW, NS and UD components.
The obtained displacement field is characterized by 1) significant uplift along the northern coast of the peninsula, with global and local maxima on the western and eastern areas, respectively, 2) westward movement of the northern part (latitude 37.1°N or higher) of the peninsula, and 3) the undulation of northward and southward displacements on the northeastern part of the peninsula. It is inferred that the first and second observed features mostly result from the oblique thrust motion of the main fault rupture, whereas the third one results from mountain slope sliding. The coseismic displacement field is remarkably consistent with the geomorphological features, indicating that the repeat of the 2024-type earthquakes is one of the main drivers of the landscape formation of the peninsula.
(Acknowledgements) SAR images were provided from JAXA through the Earthquake Working Group coordinated by the Geospatial Information Authority of Japan and JAXA. SAR pixel offset analysis was conducted using the ISCE software. We used the GEONET F5 products of the Geospatial Spatial Authority of Japan.
(Figure caption) Three-dimensional displacements obtained from the SAR pixel offset analysis and correction using the GNSS coseismic displacements. Color in the filled circles show the GNSS displacements.