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[O09-01] Overview of damage to buildings in the 2024 Noto Peninsula Earthquake
★Invited Papers
Keywords:Noto Peninsula Earthquake, Building, wooden house, Earthquake damage, Damage investigation
♦Background and overview of this report:
The Noto Peninsula Earthquake that occurred on January 1, 2024 recorded a maximum seismic intensity of 7, and buildings were damaged due to large-amplitude seismic motions, tsunamis, and the resulting slope failures, ground deformation due to ground liquefaction, and fires. It also caused major damage to buildings and infrastructure, claimed people's lives, and caused severe damage to their livelihoods. Disaster recovery is extremely difficult due to various factors such as not only damage to buildings but also the influence of infrastructure recovery status, and many people are forced to evacuate in various ways such as primary evacuation, 1.5 evacuation, and secondary evacuation. They have been forced to make a living, and there is still no prospect of recovery.
This report focuses on damage to buildings, introduces the results of several field surveys conducted by the author, and attempts to provide some insight into the causes of the damage. Please note that this is based on an inspection and survey, and detailed consideration and examination has not yet progressed, so we are only presenting one opinion at this point.
As mentioned earlier, in this earthquake disaster, damage to buildings occurred due to a variety of factors. An overview of the damage situation is described below, focusing on damage caused by earthquake motion, liquefaction, and lateral flow.
♦Damage due to earthquake motion:
While the epicenter area is located directly under the Noto Peninsula, the seismic motion amplitude observed on the ground near the epicenter area resulted in a response at a level that exceeds the level assumed by the Building Standards Act. As a result, many wooden houses in the area close to the epicenter suffered major damage, including collapse and severe damage. This region has been affected by large seismic motions over a wide area, with multiple damaging earthquakes occurring in recent years.
Particularly in the northern part of the Noto Peninsula, many wooden houses collapsed. Damage was concentrated in houses that supported heavy roof tiles but did not have sufficient earthquake-resistant elements such as bracing. However, some buildings in coastal areas were also affected by the tsunami, and others were affected by ground deformation such as liquefaction, and some buildings were not necessarily affected solely by the shaking caused by the earthquake.
Although there were not many steel-framed buildings whose structures suffered damage, there were many buildings whose exterior walls had fallen off due to deformation caused by the shaking. Damage also occurred in Toyama and Kanazawa, which are located a little further from the epicenter, with finishing materials on walls and ceilings damaged or falling off.
In addition, although there are few cases of reinforced concrete buildings whose superstructures such as pillars and beams were seriously damaged, there are cases in which a seven-story building completely collapsed on its side in Wajima, and a building that was tilted. was also seen. Some of these may have been accompanied by liquefaction, resulting in subsidence of the foundation ground and damage to the piles.
♦Damage caused by ground liquefaction and lateral flow:
In this earthquake, damage caused by liquefaction of the surface ground was seen in a wide area in various places. Damage occurred to buildings, roads, water and sewage systems in areas close to the epicenter, but damage also occurred in areas slightly further from the epicenter. Particularly in Uchinada Town and Nishi Ward, Niigata City, large-scale lateral movement occurred, and many buildings, mainly wooden houses, suffered major damage due to ground subsidence and movement. In Uchinada Town, the ground flowed 1 to 2 meters sideways, causing serious damage to infrastructure.
Even wooden houses and reinforced concrete buildings with highly earthquake-resistant superstructures can suffer severe damage from ground subsidence and lateral flow caused by liquefaction if they are not supported by foundation piles.
The Noto Peninsula Earthquake that occurred on January 1, 2024 recorded a maximum seismic intensity of 7, and buildings were damaged due to large-amplitude seismic motions, tsunamis, and the resulting slope failures, ground deformation due to ground liquefaction, and fires. It also caused major damage to buildings and infrastructure, claimed people's lives, and caused severe damage to their livelihoods. Disaster recovery is extremely difficult due to various factors such as not only damage to buildings but also the influence of infrastructure recovery status, and many people are forced to evacuate in various ways such as primary evacuation, 1.5 evacuation, and secondary evacuation. They have been forced to make a living, and there is still no prospect of recovery.
This report focuses on damage to buildings, introduces the results of several field surveys conducted by the author, and attempts to provide some insight into the causes of the damage. Please note that this is based on an inspection and survey, and detailed consideration and examination has not yet progressed, so we are only presenting one opinion at this point.
As mentioned earlier, in this earthquake disaster, damage to buildings occurred due to a variety of factors. An overview of the damage situation is described below, focusing on damage caused by earthquake motion, liquefaction, and lateral flow.
♦Damage due to earthquake motion:
While the epicenter area is located directly under the Noto Peninsula, the seismic motion amplitude observed on the ground near the epicenter area resulted in a response at a level that exceeds the level assumed by the Building Standards Act. As a result, many wooden houses in the area close to the epicenter suffered major damage, including collapse and severe damage. This region has been affected by large seismic motions over a wide area, with multiple damaging earthquakes occurring in recent years.
Particularly in the northern part of the Noto Peninsula, many wooden houses collapsed. Damage was concentrated in houses that supported heavy roof tiles but did not have sufficient earthquake-resistant elements such as bracing. However, some buildings in coastal areas were also affected by the tsunami, and others were affected by ground deformation such as liquefaction, and some buildings were not necessarily affected solely by the shaking caused by the earthquake.
Although there were not many steel-framed buildings whose structures suffered damage, there were many buildings whose exterior walls had fallen off due to deformation caused by the shaking. Damage also occurred in Toyama and Kanazawa, which are located a little further from the epicenter, with finishing materials on walls and ceilings damaged or falling off.
In addition, although there are few cases of reinforced concrete buildings whose superstructures such as pillars and beams were seriously damaged, there are cases in which a seven-story building completely collapsed on its side in Wajima, and a building that was tilted. was also seen. Some of these may have been accompanied by liquefaction, resulting in subsidence of the foundation ground and damage to the piles.
♦Damage caused by ground liquefaction and lateral flow:
In this earthquake, damage caused by liquefaction of the surface ground was seen in a wide area in various places. Damage occurred to buildings, roads, water and sewage systems in areas close to the epicenter, but damage also occurred in areas slightly further from the epicenter. Particularly in Uchinada Town and Nishi Ward, Niigata City, large-scale lateral movement occurred, and many buildings, mainly wooden houses, suffered major damage due to ground subsidence and movement. In Uchinada Town, the ground flowed 1 to 2 meters sideways, causing serious damage to infrastructure.
Even wooden houses and reinforced concrete buildings with highly earthquake-resistant superstructures can suffer severe damage from ground subsidence and lateral flow caused by liquefaction if they are not supported by foundation piles.