Journal of Earthquake and Tsunami

A rigorous solution for the kinematic response of the disconnected piles under vertically incident P-waves is presented. A new soil–pile column model is proposed with two fictitious soil columns as the extensions of the shaft along the pile top and tip. The discontinuity of the pile at the two ends is modeled using the Heaviside function to simulate the continuity of the soil–pile column. The total displacement of the soil is divided into the free-field and scattered components. The displacement of the soil–pile system is calculated in terms of the method of separation of variables and the soil–pile interaction. A parametric study indicates that for the disconnected pile, the displacement at the pile top increases significantly with the increase of the cushion thickness, and its effect on the scattered field is weak. The axial force of the disconnected pile decreases gradually with the increase of the cushion thickness. The displacement and axial force of the disconnected pile are significantly influenced by the slenderness ratio of the pile.

Difficulty in maintaining tuning due to water depth fluctuation makes overhead water tanks (OWTs) ineffective as tuned liquid or mass dampers. Recently, a semi-active damper involving OWT, that varies the stiffness of the tank-supporting columns with liquid depth variation to maintain the impulsive frequency of the tank constant at a value required for tuning, has been proposed. In this paper, the concept is extended to develop a passive tuned damper involving the OWT (PTD-OWT), which is more reliable, cost-effective, and has a simpler configuration than its semi-active counterpart but achieves the same objective as the latter. For the PTD-OWT, a novel mechanism involving a spring-supported platform, a rigid frame, and tank-supporting columns is developed. The working principle and mathematical model of the PTD-OWT are presented followed by an illustrative design example considering the host building undergoing base excitation. The results revealed that the PTD-OWT remains tuned and thereby performs consistently despite wide variations in water depth in the tank. Significant reductions have been achieved by the PTD-OWT in peak and root-mean-square displacement and acceleration responses of the structure for a variation in liquid depth between 100% full tank to empty tank condition, with the maximum fall in control achieved as only 6.8%. A comparison of PTD-OWT is made with the case when the tank is designed as a conventional passive tuned mass damper (TMD) without the provision for maintaining tuning. The conventional mass damper suffers significant performance degradation as liquid depth fluctuates in the tank.

The devastating Chichi earthquake in Taiwan in 1999 highlighted the importance of disaster prevention and relief operations. In response to the challenge of extreme events and compound disasters, the National Science and Technology Center for Disaster Reduction (NCDR) contributes to operations at the Central Emergency Operation Center (CEOC) of Taiwan by providing integrated information and timely suggestions, and it delivers a common operational picture to central and local governments through a decision support system. This study was undertaken to explore the emergency response towards the reconnaissance of earthquake disasters in Taiwan to illustrate how resilient cities ensure rapid crisis response with a focus on the NCDR disaster response decision support system. This study examines the decision support system used following the 2016 M_L 6.6 Meinong earthquake. The results demonstrate that the first line of relief for the emergency response commander is data-driven decision-making.

In this study, a probabilistic seismic hazard analysis (PSHA) using a traditional approach with a simple logic tree that handles a single-site sigma is developed to present a site-specific ground motion hazard. The analysis relies on the accelerometer data collected from the I-Lan Plain, a deep sedimentary basin in Northeastern Taiwan where hundreds of earthquake sequences (with $M_w$ = 4.0–7.6) were recorded by the Taiwan Strong Motion Instrument Program (TSMIP) network between 1992 and 2016. The performance of PSHA on soil and hard sites is evaluated from two representative instrumented sites (ILA048 and ILA025), using residual measures available from a ground motion model (GMM) developed by [] (referred to as Ph23), from which the uncertainties in site terms (${\delta S2S}_s)$ and single-site sigma (${\sigma }_{SS,S})$ are estimated. We address key conceptual issues in the current PSHA approach and introduce a new region- and site-specific PSHA approach in which (1) site-to-site variability (${\varphi }_{S2S})$ is estimated as a random variance in a mixed effects GMM regression and (2) the GMM site-specific single-site sigma (${\sigma }_{SS,S})$ is replaced with a generic site-corrected aleatory variability (${\sigma }_0$). Comparison of the region- and site-specific hazard curves from our method against the traditional method estimates at two well-recorded sites in the I-Lan region shows an approximate 50% difference in prediction ground motion values considering for 2% and 10% probability of exceedance in 50 years.

The overtopping-inundation process of a tsunami results in the collisions of drifting objects on the coast, which damage structures, thereby increasing the risk of collapse. This study conducted laboratory experiments on the collision between a drifting container caused by the overtopping-inundation process of a solitary wave and a fixed port crane’s leg. The movement trajectory and velocity of the container as well as the collision velocity by solitary wave inundation, were analyzed using motion analysis software. Overall, increasing solitary wave scale, collision velocity, and drifting object weight and decreased distance between the two objects tended to increase the collision force. However, different experiment results were also obtained due to pitching in objects that fully floated without bottom friction owing to the solitary wave bore. This resulted in line-to-surface collisions. Thus, surface-to-surface contact occurred under the incomplete floating condition owing to the difficulty because of interference with the bottom; however, the collision force decreased under complete floating conditions owing to line-to-surface contact. Therefore, the contact condition according to the floating behavior must be considered a parameter while predicting the collision forces of drifting objects. Thus, surface-to-surface contact occurred under the incomplete floating condition owing to the difficulty because of interference with the bottom; however, the collision force decreased under complete floating conditions owing to line-to-surface contact. Therefore, the contact condition according to the floating behavior must be considered a parameter while predicting the collision forces of drifting objects.

On February 6, 2023, two catastrophic earthquakes occurred on the East Anatolian Fault. The earthquakes had magnitudes of Mw = 7.7 and 7.6 and struck Kahramanmaraş-Pazarcık and Kahramanmaraş-Elbistan, respectively. The Kahramanmaraş-Pazarcık earthquake was triggered at 04:17 local time on the Dead Sea Fault (a branch of the East Anatolian Fault). The last earthquake on the addressed fault occurred about 500 years ago. The recorded peak ground acceleration (PGA) at the Pazarcık station reached 2.05g. In addition, the Pazarcık earthquake triggered two independent earthquakes, the Nurdağı and Islahiye earthquakes, which occurred 10 min later than the Pazarcık earthquake. However, the last earthquake, with its epicenter in Kahramanmaraş-Elbistan, struck at 13:24 local time. The recorded PGA for the Elbistan earthquake is 0.68g. This study aims to present the fault rupture mechanism of the February 6, 2023, Kahramanmaraş earthquakes, earthquake characteristics, and to evaluate the performance of masonry dwellings during the Kahramanmaraş earthquake doublet, which affected 10 provinces and numerous towns and villages. This paper also aims to illustrate the damage and failure mechanisms of the masonry dwellings, despite unexpectedly high accelerations that exceeded the design spectrum in the field, specifically in Kahramanmaraş, Gaziantep, Hatay, and Malatya, according to the current earthquake code in use.