Abstract
Earthquakes have always been considered a threat to human settlements. According to the results of archeological studies, one of the behavioral patterns of humans in the face of earthquakes has been to permanently change their place of residence. The fact that the major part of Iran’s plateau is located in one of the earthquake-prone areas of the planet makes the research and investigation about the impact of these natural events on the human way of life, especially in the prehistoric era, to be studied more. In this direction and with the aim of assessing the impact of this natural phenomenon in Central Zagros and in order to know how humans react to this phenomenon, it has been studied. Our main question in this research revolved around how ancient earthquakes can be identified in archaeological contexts, and based on what evidence? What were the effects of this destructive phenomenon on the change in people’s biological patterns in the period after the incident? The information of this research has been collected from the archaeological excavations of Godin Tepe, Kangavar and Baba Kamal Tepe Tuiserkan from the Bronze Age to the end of the Iron Age III BC. In the following, based on the evidence of the severity of the destruction caused by the earthquake, an attempt has been made to reconstruct the intensity scale of the earthquakes based on the Mercalli scale. As a result, it was determined that the occurrence of destructive earthquakes with an intensity of more than 6 degrees on the Richter scale in the area of the investigation, especially in the Bronze and Iron Age, was not unrelated to the impact of climate change caused by the intensity of melting glaciers and the change in the hydrological conditions of the earth. After the Late Bronze Age, the events caused by this event caused the relative collapse of many settlements until the Iron III period, and practically at this time, the population of the region was reduced to the minimum possible.
Keywords: Ancient Earthquakes, Archeology of Eastern Central Zagros, Godin Tepe, Baba Kamal Tepe, Bronze & Iron Age.
Introduction
Throughout history, villages and cities have always been threatened by cultural or natural disasters such as war, fire, earthquakes, floods, and storms. Earthquakes are natural events that have been important causes of damage and destruction for humanity. The land of Iran, due to its location in the middle part of the Alpine-Himalayan orogenic belt, is always exposed to high-intensity earthquakes and is known as one of the centers of destructive earthquakes.
Studying and researching the remaining signs of ancient earthquakes in Iran according to archaeological data can provide information on long-term seismicity in different parts of this land for researchers. By using archaeological data and matching their information with specific regional geological conditions, it tries to recognize the occurrence of earthquakes that occurred in prehistoric times and their effects on the formation of settlement patterns.
In this regard, the Kangavar Plain and the eastern region of Central Zagros have been studied and researched, focusing on the archaeological information of Godin Tepe and Baba Kamal Tepe. This research aims to investigate and identify the archaeological studies carried out in Godin Tepe and East Central Zagros to study and investigate the events that are suspected to be natural earthquake hazards in Godin Tepe and Baba Kamal. Also, the role and effect of these earthquakes in the distribution of settlements after the earthquake will be studied in the region, seeking to answer questions such as: How can the earthquake during the settlement of Tepe Godin and Tepe Baba Kamal be recognized? In what period of the settlements of Tepe Godin and Baba Kamal and with what approximate magnitude did these earthquakes occur? How can the role and effect of these earthquakes be explained by the change and distribution of settlement patterns in the post-earthquake era of the region? In the investigations and field studies, the evidence and signs of earthquakes in the Bronze Age of Godin Tepe Kangavar and the Iron Age of Baba Kamal Tepe Tuysarkan have been observed, which can be the hypothesis proposed in this regard.
Discussion
The investigation of different cultural layers showed that the Godin site experienced at least three important events that changed the lives of the people at that time. Evidence of these events can be seen in layers III5, III4, and III2 in the Bronze Age in different years between 2400 and 1650 BC. Yang, the explorer of Godin Tepe, believes that the earthquake in these phases caused destruction and destruction in the buildings, which caused the settlement to leave and the site to be abandoned at the end of phase III2. Among the damages caused by the earthquake in Godin Tepe and Baba Kamal, the following can be mentioned:- Collapse of ceilings and walls;
• Collapse of ceilings and walls;
• Debris left on the floor of the rooms;
• Crushing of healthy pottery under the debris;
• Humans being buried under the rubble and being killed by falling bricks;
• Cracks in the walls
• Abandonment of the site after the earthquake
Using the empirical relationships and the Mercalli intensity scale (MMI), we can attribute an average magnitude of 6 to Godin III2 and Iron III Baba Kamal events, and an average of 7 to Godin III4 and III5 events.
According to the archaeological surveys conducted in the studied area, it can be seen that the region has experienced a decrease in human settlements and population collapse in the periods after the Godin earthquakes. The reduction of settlement areas during different phases of the Middle and New Bronze Age compared to the previous layers is observed in the plains of Kangavar, Nahavand, Asadabad, Tuysarkan, Malair, Sanghar, Sahne and Borujerd. In layer III2, the number of sites with artifacts from this period increases in the region. Young and Henrikson believe Godin III2 pottery at the same time as this phase, or probably at the end of this phase, we see an increase in the nomadic process, and it is likely that this issue has influenced the increase in the number of ancient sites.
During the Iron Age, the central Zagros region underwent changes that led to the reduction of human settlements in Iron Age I. Archaeological data show that there was no population density in Iron Age I/II in areas like Kangavar Plain. Several abrupt climate changes occurred during the Holocene epoch. This change in weather conditions, along with the earthquakes in the region, could have been a factor that affected the settlement of human populations and settlements in the region in prehistoric times and caused a change in the settlement pattern and a decrease in human populations.
Conclusion
In this study, in order to investigate the seismicity of the eastern central Zagros region and the earthquakes that occurred in the Bronze and Iron Ages of the region, the collection of evidence and documentation of the earthquakes of the mentioned periods, obtained from archaeological excavations, was collected. Earthquake evidence in Baba Kamal Tuiserkan Tepe was obtained in the form of disturbed layers with cracks in the Iron Age III clay structure. Also, these signs have been observed in the form of ruins and human remains found under the debris, scattered artifacts and pottery on the floors of residential houses, and cracks on the walls in the Bronze Age of Godin Kangavar Tepe. Godin Tepe has witnessed three destructive earthquakes in phases III5, III4, and III2, which, in addition to the destruction that followed, caused the area to be abandoned for a long time. The abandonment of the area can also be seen on Baba Kamal hill, which was without settlement until the Parthian period.
After the Godin III period until the end of the Iron Age I and II, the reduction of settlement areas is observed not only in the Kangavar plain but also in most of the surrounding areas of the Kangavar plain in the east of central Zagros. However, some researchers have pointed out the change in weather conditions as another reason for the decrease in the number of settlements in the region, and climatological research has proven that during this period, climatic dry events occurred in Southwest Asia. According to the seismicity of the central Zagros region and the evidence of earthquakes from Godin Tepe and Baba Kamal, these climate changes, along with the occurrence of earthquakes in this region, are both factors that have provided unfavorable conditions for life in the region at the same time. Based on the data obtained from the Godin and Baba Kamal sites, a magnitude of 7 was estimated for the Godin earthquakes of layers III5 and III4 and a magnitude of 6 for the earthquakes of Godin layer III2 and Iron Age III of Baba Kamal.