Chapter 15. The Active Taiwan Mountain Belt

Taiwan is located at an active plate boundary and prone to earthquake hazards. To evaluate the island's seismic risk, the Taiwan Earthquake Model (TEM) project, supported by the Ministry of Sciences and Technology, evaluates earthquake hazard, risk, and related social and economic impact models for Taiwan through multidisciplinary collaboration. One of the major tasks of TEM is to construct a complete and updated seismogenic structure database for Taiwan to assess future seismic hazards. Toward this end, we have combined information from pre-existing databases and data obtained from new analyses to build an updated and digitized three-dimensional seismogenic structure map for Taiwan. Thirty-eight on-land active seismogenic structures are identified. For detailed information of individual structures such as their long-term slip rates and potential recurrence intervals, we collected data from existing publications, as well as calculated from results of our own field surveys and investigations. We hope this updated database would become a significant constraint for seismic hazard assessment calculations in Taiwan, and would provide important information for engineers and hazard mitigation agencies.

Section: Seismogenic Structures Of Taiwan and Their Parametersmentioning

confidence: 99%

A New On-Land Seismogenic Structure Source Database from the Taiwan Earthquake Model (TEM) Project for Seismic Hazard Analysis of Taiwan

Ôta¹,

Chuang²,

Chen³

et al. 2016

“…The oblique collision between the Luzon Arc and Eurasian continental margin since the Late Miocene has led to the formation of Taiwan Island (Suppe 1981;Ho 1986) and the process is still actively propagating to the south (Suppe 1987). The Manila Trench subduction zone which developed between the South China Sea and the northern Philippines is composed by well-developed accretionary wedge, forearc basin, and the Luzon volcanic arc (Molli and Malavieille 2011).…”

Section: Study Area and Backgroundmentioning

confidence: 99%

Sedimentological characteristics and seafloor failure offshore SW Taiwan

Hsu

et al. 2018

In this study, analysis results reveal two main deposition zones are located at the flank of upper Gaoping Submarine Canyon and Lower Fangliao Basin offshore SW Taiwan. The non-event related sediments deposited in past 150 years (i.e., 632 Mt km -2 ) was delivered and transported from Gaoping River by suspension process with tides and coastal currents and gradually spread out offshore. Meanwhile, the total mass of accumulation sediments is 1922 Mt km -2 , accounting for 40% Gaoping River's sediment load and suggesting that the deposition process is mainly controlled by natural hazards. Sedimentation rates in much of the study area, except in the main deposition zones, are less than 0.5 cm yr -1 (5 m kyr -1 ). Compared with the studies at the instability seafloor caused by high sedimentation rates (~30 m kyr -1 ), the offshore southwestern Taiwan is relatively stable. In this study, we also discovered a series of sediment waves located on the upper continental slope between Gaoping and Fangliao Submarine Canyons, which is related to the creeping process on seafloor. In summary, our results reveal the fluid activities, existence of weak layers and earthquake triggering are potential factors which might induced seafloor failures offshore southwestern Taiwan.

“…Therefore, lots of earthquakes with deep focal depth occur in the northeastern part of Taiwan in the area east of 121.5°E and north of 24°N. The seismicity occurs mostly in the western foothill province where the fold-andthrust of imbricate structures and thin-skinned tectonics control the earthquake behaviors (Suppe 1987).…”

Section: Zoningmentioning

confidence: 99%

Taiwan Earthquake Occurrence Probability Estimation from Regional Source Model Since 1900

Wen¹,

Wu²,

Huang³

et al. 2014

Taiwan is located on the boundary between the Eurasia Plate and Philippine Sea Plate, which is a very high seismicity rate area. We begin calculating the earthquake occurrence probability using four recurrence models to mitigate seismic disasters. We focus on estimating the occurrence probabilities for regional earthquake sources based on the catalog released by the Central Weather Bureau over the period from 1900 to 2011. According to the tectonic and seismicity characteristics areas in and around Taiwan are divided into several zones for shallow and deep earthquakes. We utilize four recurrence models to estimate the earthquake occurrence probabilities over the next 30 and 50 years, respectively. In addition, the grid-based probabilities in 0.1° × 0.1° spatial size are calculated using the micro-zoning method. The results obtained from four recurrence models show that areas with high values over the next 30 and 50 years are correlated with two subduction zones and a suture zone. High probabilities in the western foothills appear highly active tectonic. Moreover, the high values appear at in Eastern Taiwan, offshore Hualien County. There are discrepancies between the results from the four models. The highest grid-based probability is about 3.0, 3.5, 2.5 and 3.5% for the Lognormal, Gamma, Exponential, and Weibull models, respectively. The inland probabilities are below 0.5% for the results from Lognormal, Gamma, and Weibull models. Even so, the results from the Exponential model are upmost in the range from 0.5 -1.0%.