Updates to the on-land seismogenic structure source database by the Taiwan Earthquake Model (TEM) project for seismic hazard analysis of Taiwan

Abstract

To provide information towards understanding Taiwan's earthquake hazard and risk, the multidisciplinary Taiwan Earthquake Model (TEM) project, supported by the Ministry of Sciences and Technology, had prepared and published a first version of seismic hazard assessment maps of Taiwan in 2016, together with an on-land seismogenic structure database of the island. In the years following the publication of this first version, we have constructed an updated version of this database. Seven structures were identified and added to the database. Based on additional information, we have also updated the structural parameters of four existing structures, as well as systematically updated the parameters of all structures to include more complete parameter uncertainties. This update of the database represents the most up-to-date information of seismogenic structures in Taiwan, and would provide better constraints for future seismic hazard assessment and mitigation studies.

Mud Diapir or Fault‐Related Fold? On the Development of an Active Mud‐Cored Anticline Offshore Southwestern Taiwan

“…This rate accounts for only 50% of the GNSS‐based value, meaning that some structures may have to take up twice or more shortening than average. It is possible that a large fraction of the remaining shortening is absorbed by a few major structures near the deformation front, such as the offshore extension of the Chishan and the Youchang fault (Shyu et al., 2020), and even the deformation front itself (Lacombe et al., 2004). The exact amount of shortening across each of these anticlines is beyond the scope of this study, and yet this study provides a workflow to realize such an analysis in the future.…”

“…Leveling survey and InSAR analysis also show rapid ground uplift over some proposed diapiric anticlines, at rates of 18-37 mm/yr (Ching et al, 2016;Tsukahara & Takada, 2018). Despite the popularity of attributing anticlinal deformation to mud diapirism in southwestern Taiwan, studies reveal a significant influence of active fault systems in this area's geology and geomorphology (e.g., Y.-G. Chen & Liu, 2000;Gong et al, 1996Gong et al, , 1998Hsieh & Knuepfer, 2001;Liu et al, 2021;Mouthereau et al, 2001;Shyu et al, 2005Shyu et al, , 2016Shyu et al, , 2020. Disagreement therefore exists regarding whether the anticlinal structures are caused by mud diapirism, or whether they are simply fault-related folds (e.g., Biete et al, 2018;S.-T. Huang et al, 2004;Lacombe et al, 1999).…”

Probabilistic seismic hazard assessment for Taiwan: TEM PSHA2020

“…An update could include outcomes of the Reevaluation of Probabilistic Seismic Hazard of Nuclear Facilities in Taiwan Using SSHAC Level 3 Methodology. Although we have updated the seismogenic structure database based on state-of-the-art geomorphology and geology studies (Shyu et al, 2020), we will incorporate seismogenic parameters obtained from geodetic research. In respect to the GMPEs, some new sets of GMPEs, for example, Chao et al (2020) and Phung et al (2020), will be discussed, and their epistemic uncertainties (Phung et al, 2019) will be evaluated and considered in a logic tree.…”

“…The TEM PSHA2015 implemented the seismogenic structure database summarized by Shyu et al (2016), which incorporated 38 seismogenic structures with planar geometries and characteristic magnitudes, that is, a single magnitude and fixed recurrence interval for each structure. This database was updated (Shyu et al, 2020) to include six newly identified structure sources: the Chushiang, Gukeng, Tainan frontal, Longchuan, Youchang and Fengshan hills frontal structures (ID 39–44, respectively; corresponding fault alignment of each source is presented in Figure 1a). Also, based on additional evidence, such as seismic profiles, dip angles of some sources are suggested to be depth variable, with a gentler dipping at depth (Table 1).…”

Applying unsupervised machine-learning algorithms and MUSIC back-projection to characterize 2018–2022 Hualien earthquake sequence

“…S1). Among (Cheng 1997), 1986-1992(Kao et al 1998Jian et al, 2018a, b), where blue lines indicate active faults (Shyu et al, 2020) them, the 1951 sequence includes three strong earthquakes (M ~ 7) struck the Hualien region on the same day (Cheng et al 1997). These earthquakes also triggered another two major events one hundred kilometers to the south in November 1951 (Cheng et al 1997;Chen et al 2008;Chung et al 2008).…”