5:15 PM - 7:15 PM
[SSS10-P12] High-resolution estimation of the Boso Slow Slip Events in 2011, 2013–2014, 2018, and 2024 based on inflection point analysis of high-rate GNSS data
Keywords:SSE, Boso Peninsula, Slip distribution, Inflection point analysis
Previous research by Fukuda (2018) utilized daily solutions of Global Navigation Satellite System (GNSS) data from 1996 to 2014 to conduct an inversion analysis based on the network inversion filter. The study demonstrated that the nucleation patterns of slow slip events (SSEs) off the Boso Peninsula were not uniform. For example, the nucleation of the 2011 SSE was more rapid, whereas the 2013–2014 SSE initiated more gradually.
This study focuses on the diversity of SSEs. We estimate the detailed spatiotemporal evolution of four Boso SSEs—those occurring in 2011, 2013–2014, 2018, and 2024—using precise point positioning (PPP) solutions sampled at five-minute intervals from high-rate GNSS data provided by the Nevada Geodetic Laboratory. To fully utilize the high temporal resolution of GNSS, we apply change-point detection based on sparse modeling, as proposed by Taylor & Letham (2017), to extract key characteristics related to the onset, growth, and termination of each SSE from the time-series data at individual observation sites. Subsequently, we employ a Hamiltonian Monte Carlo method incorporating a horseshoe prior distribution (Carvalho et al., 2009) to estimate the spatiotemporal evolution of slip distribution, allowing for localized regions of significant slip. Although the temporal resolution varies slightly among events, we set it to approximately 20 hours, which is less than one day.
As a result, we successfully characterized the four SSEs. The 2011 SSE occurred "at the most inland location," "propagated relatively simply in the up-dip direction," and exhibited "a more abrupt onset than termination." The 2013–2014 SSE occurred "offshore, distinct from the 2011 SSE," and was "smaller in scale with limited propagation." The 2018 SSE "initiated at a location similar to the 2013–2014 SSE, with slip extending partially into the 2011 SSE region," "propagated offshore with a change in direction toward the end," and had "a termination more abrupt than its onset." The 2024 SSE "occurred in a similar location to the 2013–2014 SSE but was larger in scale."
Although SSEs are broadly categorized as "repeating events," our findings suggest significant variability among individual occurrences. Unlike earthquakes, SSEs are expected to have minimal effects from dynamic rupture processes, implying that quasi-static frictional heterogeneity on spatial scales of less than approximately 10 km may play a crucial role.
This study focuses on the diversity of SSEs. We estimate the detailed spatiotemporal evolution of four Boso SSEs—those occurring in 2011, 2013–2014, 2018, and 2024—using precise point positioning (PPP) solutions sampled at five-minute intervals from high-rate GNSS data provided by the Nevada Geodetic Laboratory. To fully utilize the high temporal resolution of GNSS, we apply change-point detection based on sparse modeling, as proposed by Taylor & Letham (2017), to extract key characteristics related to the onset, growth, and termination of each SSE from the time-series data at individual observation sites. Subsequently, we employ a Hamiltonian Monte Carlo method incorporating a horseshoe prior distribution (Carvalho et al., 2009) to estimate the spatiotemporal evolution of slip distribution, allowing for localized regions of significant slip. Although the temporal resolution varies slightly among events, we set it to approximately 20 hours, which is less than one day.
As a result, we successfully characterized the four SSEs. The 2011 SSE occurred "at the most inland location," "propagated relatively simply in the up-dip direction," and exhibited "a more abrupt onset than termination." The 2013–2014 SSE occurred "offshore, distinct from the 2011 SSE," and was "smaller in scale with limited propagation." The 2018 SSE "initiated at a location similar to the 2013–2014 SSE, with slip extending partially into the 2011 SSE region," "propagated offshore with a change in direction toward the end," and had "a termination more abrupt than its onset." The 2024 SSE "occurred in a similar location to the 2013–2014 SSE but was larger in scale."
Although SSEs are broadly categorized as "repeating events," our findings suggest significant variability among individual occurrences. Unlike earthquakes, SSEs are expected to have minimal effects from dynamic rupture processes, implying that quasi-static frictional heterogeneity on spatial scales of less than approximately 10 km may play a crucial role.