To limit the probability that the expected seismic distortion of the building structure will damage or displace unreinforced masonry elements, which could lead to elements of the building falling or sliding, which could lead to harm to persons.
To limit the probability that the lateral seismic force used for unreinforced masonry elements will not take into account all the factors that affect the expected magnitude of the inertial seismic force, which could lead to elements of the building falling or sliding, which could lead to harm to persons.