Overturned shelves and fallen objects scattered on floors are one of the most frequently observed forms of nonstructural damage after earthquakes. The term 'clutter' is adopted in this study to represent this type of damage. Clutter may cause obstructions and thus hinder the use of a room. Making a seismic evaluation of clutter is a daunting task, due to the diversity of the types of shelves and objects and the way the objects are stored. Nonetheless, in order to achieve performance-based seismic evaluation, especially for critical facilities such as hospitals, it is reasonable to undertake the estimation of clutter when examining the association between the performance of structural and nonstructural elements. Of particular interest in this paper is clutter caused by objects stored on medicine shelves in pharmacies, which are one of the critical departments for delivering post-earthquake emergency care. Shake table tests were conducted on three conventional types of medicine shelves. Sinusoidal waves and earthquake motions were input uniaxially. The results of the tests using the sinusoidal wave input indicated the relationship between the input excitation intensity and clutter level expressed in scattering distance from the front of the shelf. Tests using earthquake motion input were then conducted and the results were compared with those for sinusoidal waves. Based on a comparison of the results from these tests, criteria for the seismic evaluation of clutter caused by medicine shelves due to earthquakes were proposed. medical services [1]. Pharmacies have a high risk of sustaining clutter in an earthquake as they house a large number of shelves that are loaded with many medications [2]. The immediate normal supply of medicine is thus directly influenced by the level of clutter in pharmacies, and so this study focuses on this problem in the aftermath of a seismic event.The overturning of an unanchored shelf is considered to be the most serious clutter situation caused by a single shelf as it occupies the floor area of its height by its width after it overturns. The overturning of objects has drawn much research attention as it can be a threat to human safety. Much research, both numerically and experimentally, has been conducted on the overturning of rigid bodies. To evaluate whether a rigid body will overturn when subjected to an earthquake, the equations (see Equations (1) and (2)) proposed by Milne [5] and Ishiyama [6] are usually adopted to estimate the overturning acceleration A 0 , and velocity V 0 , which are the lower limit of the peak acceleration and velocity of the input excitation necessary to overturn a rectangular rigid body that is being restrained from sliding, respectively.

The 2018 Mw 6.4 Hualien earthquake generated a large peak-to-peak velocity of over 2  m/s, with a period of 3 s at the south end of the Milun fault, which resulted in the collapse of five buildings. To investigate the shallow subsurface soil structure and evaluate possible effects on the ground motion and building damage, we performed microtremor measurements in the Hualien basin. Based on the velocity structure jointly inverted from both Rayleigh-wave dispersion curves and microtremor horizontal-to-vertical spectral ratio data, we found that the shallow subsurface structure generally deepens from west to east. Close to the Milun fault, the structure becomes shallower, which is consistent with faulting during the 2018 earthquake and the long-term tectonic displacement. There is no significant variation for the site conditions in the north–south direction that can explain the large peak ground velocity in the south. As a result of the dense measurements in the heavily damaged area, where three high-rise buildings totally collapsed, these locations have the average S-wave velocity of the upper 30 m (AVS30) values and are relatively high compared to the more distant area from the Meilun River. This is somewhat unusual, because lower AVS30 values indicating softer ground conditions are expected close to the river. We did not find any characteristic subsurface soil structure that may contribute to the building collapses. The large 3 s pulse was probably generated by source effects, rather than subsurface soil amplification.