## 3 Observed Damage Mechanisms in Eastern T\(\ddot{\text{u}}\)rkiye's Masonry Buildings  
Masonry has historically been the primary building method in parts of eastern T\(\ddot{\text{u}}\)rkiye, due to the accessibility of local resources like stone and adobe, as well as enduring vernacular customs [38]. These construction techniques often use basic mortar mixtures and little or nonexistent reinforcing, and they depend on empirical guidelines for sizing walls and roofs [4]. Although these traditions have cultural importance, they often lack designed seismic details, making them vulnerable to moderate-to-high ground shaking. The global kinds of masonry include URM, confined masonry (CM), reinforced masonry (RM), and  
Figure 3: Recorded earthquakes having a magnitude greater than 5.0 in the instrumental period. autoclaved aerated concrete (RAAC). The URM types lack reinforcement, or the reinforcing percentage is far below the levels mandated by earthquake regulations. The prevalent material types for URM are bricks, hollow concrete blocks, hollow clay tile units (HCT), stone, and adobe. In CM, the structural system consists of horizontal and vertical reinforced concrete confining components; in RM, vertical and horizontal reinforcing bars are integrated into the walls. The quality of stone masonry is influenced by quarrying techniques, bonding configurations, and mortar durability. Certain villages use random rubble construction, while others choose to more precisely cut stone blocks to enhance interlocking. Adobe building is notably widespread, particularly in areas with an abundance of clay-rich soil. Notwithstanding adobe's thermal advantages, its seismic performance is compromised by brittle behavior, limited tensile strength, and quick cohesion loss under cyclic stress. The mid-20 th century marked a period of partial modernization characterized by the growing accessibility of cement, steel, and industrially produced bricks. This evolution facilitated the integration of concrete intells, ring beams, or partial reinforcement in crucial areas of the construction (e.g., corners, openings). Although these modifications contributed to alleviating specific failure mechanisms, their application was often inconsistent. In numerous cases, retrofitting was executed informally, lacking proper design calculations or adherence to building codes [39]. As a result, the resulting hybrid systems frequently display irregular stiffness distributions, compromised mortar layers, and unpredictable overall behavior under seismic forces. Today, masonry construction in eastern Turkriye exists in a transitional space between vernacular and engineered approaches. However, enforcement remains a challenge in remote areas, where local masons may not be fully conversant with the latest guidelines [40]. This gap between regulation and practice leaves a significant portion of the building stock at heightened risk of seismic damage. Field investigations indicated that, among masonry kinds, URM structures are mostly favored in eastern rural Turkriye. Consequently, the identified damage to masonry structures may be classified as resulting from either out-of-plane or in-plane behavior, as seen in Figure 4. The former may be designated as the primary damage mode, resulting from seismic forces perpendicular to the wall, while the latter may be termed the secondary damage mode, arising from in-plane forces. If the walls of a structure are inadequately linked at floor levels due to out-of-plane behavior, they will split at the corners and intersections, resulting in instability and potential partial or whole collapse. Figure 4: Schematic illustrations of (**a**) out-of-plane behavior, and (**b**) in-plane behavior. [PERSON] [4] noted that out-of-plane behavior is less essential for seismic resistance than in-plane behavior due to the homogeneous distribution of walls in both orthogonal directions, the geometric requirements for shear walls, and the connections between walls and floors.