5:15 PM - 7:15 PM
[SCG55-P30] Revisiting ranging data of Acoustic Distance Meter at the trench axis off Iwate
Tohoku University has conducted campaign survey using seafloor Acoustic Distance Meter (ADM) to monitor crustal deformation near the trench axis at four sites from off Fukushima to off Nemuro along Japan and Kuril trenches. Other than of Fukushima, where shallow-dip after slip was thought to be ongoing during the campaign period, no significant shortening across the trench axis was observed at the remaining three sites and interpreted that the up-dip edge of overriding plate kinematically follows on the incoming oceanic plate. However, since resolution of ADM measurement is high as 1 mm per 1 km baseline length, we often observed long timescale but small change in the baseline length, which cannot be easily interpreted whether artifact by systematic error or actual geodetic signal. Therefore, we have to be more careful in understanding the raw data to address such slight movement as smaller than global plate motion by one order.
We already reported the ADM survey during 2019 to 2021 (~2 years) off Iwate that no shortening was observed beyond the measurement accuracy (~2 cm/yr) as a preliminary result. However the analysis excluded the baselines including an upset instrument and IPR(Indirect Path Ranging)system. Then we started re-analyzing the data for full baseline combinations. At this moment, baseline with the upset instrument has processed in addition discrete attitude data due to poor recording resolution (0.01 deg) were refined through filtering in attitude correction, which slightly contribute to reduce the scatter in all the baseline change. Now we are processing IPR data, which may provide some information on the relatively larger apparent baseline changes up to 2 cm in long period, which temporally considered as drift in attitude sensor or temperature disturbance which cannot be represented by temperature data only at the both end of the baseline. We plan to show the result of all the baseline combinations including IPR in the presentation.
We already reported the ADM survey during 2019 to 2021 (~2 years) off Iwate that no shortening was observed beyond the measurement accuracy (~2 cm/yr) as a preliminary result. However the analysis excluded the baselines including an upset instrument and IPR(Indirect Path Ranging)system. Then we started re-analyzing the data for full baseline combinations. At this moment, baseline with the upset instrument has processed in addition discrete attitude data due to poor recording resolution (0.01 deg) were refined through filtering in attitude correction, which slightly contribute to reduce the scatter in all the baseline change. Now we are processing IPR data, which may provide some information on the relatively larger apparent baseline changes up to 2 cm in long period, which temporally considered as drift in attitude sensor or temperature disturbance which cannot be represented by temperature data only at the both end of the baseline. We plan to show the result of all the baseline combinations including IPR in the presentation.