Julian Event
The Julian Event is a natural disaster that took place in and around the Julian Sea in 7118 or 7119. The current majority view among scientists is that the event was a meteor strike that triggered a long period of volcanic activity in and around the Julian Sea. There is however no consensus about the exact cause, extent or impact of the event due to poor historic references and some conflicting archaeological evidence. Some scientists stil defend the possibility of a large volcanic event or a massive submerged landslide off the Raguna Roku island as possible causes.
Historical background
When Anarian explorers entered the region in the 7120's to 7140's, they encountered hardly any nation states or important cities around the coastline of the Julian Sea. It led to a wave of colonisation by Anarian nations like Auresia, Casella, Halland, Helreich and Livaria. Explorations also noted a significant difference in natural vegetation between low lying areas and more hilly regions, but attributed them to geological and climatic causes. Researchers even found gaps in recorded history in most regional accounts, as well as references to substantial flooding around the same time, followed by a colder period resulting in failed harvests. Nearby civilisations in less affected areas, like the island of Nelyasyat or even Kamura, only had records of more common natural disasters having occurred in the region. No one really made an analysis of the available records at the time.
The inclusion of the Kakuri people from the Fisks islands into Vittmark triggered an interest in pre-colonial history of the Julian Sea region in the 7570's. Kakuri folklore was full of references to a major disaster having taken place around 7120, but the nature of their language made it difficult to get a good overview. The Kakuri people themselves are an odd isolated ethnic group that upon further research seemed linked to Davaian and Altaian ethnicities from way further north. In 7599 the Vittmarker scientist Fredrik Strand formulated a first hypothesis about a so-called Julian Event, a natural catastrophe that wiped out all of civilisation around the Julian Sea around 7120. His hypothesis pointed out the centrally located Roku volcano as the most likely candidate for the cause of the disaster.
But when looking for archaeological evidence for a catastrophic volcanic event, it turned out that the event left evidence of tsunami's reaching 100-400 meters in height on all coastlines, which most probably not could have been caused by a volcanic event. A submerged landslide was posted as an hypothesis, as well as a more unlikely meteor impact. Even though no impact crater has been identified yet on the sea floor, most of the scientific evidence supports the theory of a sudden impact on a larger scale than a major volcanic eruption, especially because of the size of the following tsunami's.
During the last centuries, scientists are trying to combine archaeological evidence with recent interpretations of local recorded history in order to describe the event and its aftermath more thoroughly.
Main hypothesis: sequence
The main hypothesis supported by the majority of scientists is that of a near vertical meteor impact, or serial impact of a single meteor having broken up when entering the planet's atmosphere. The meteor impact could have been as good as vertical based on the evidence of similar height tsunami's on all coast lines, with considerably higher tsunami's in straits and bays. However, such a trajectory of an extra-Gothan meteorite might have affected the arc surrounding the planet, but no such disturbance has been recorded.
The estimated size would be around 400 to 500 meters in diameter if it would hit a sea at about 800 to 1000 m deep. But the impact location could affect the resulting tsunami's size a lot. According to one simulation, the meteor would have impacted in an area south of Carlsö in Mirei state, current day Sokoku. In this hypothesis, the consequences of an impact in the ocean at such water depths are dramatic. It would result in an 800-meter thick water column, as well as the asteroid and a substantial volume of sediment being instantly vaporised—with a large fireball visible hundreds of kilometers away. It would explain 300-400 meter high tsunamis striking the nearest coastlines.
The sequence of this hypothesised near vertical strike is as follows. A meteor this size would have traveled at 10 to 20 km/s before impact. This means that the meteor only entered the atmosphere 4-10 seconds prior to meeting the sea surface (t=0). Two seconds after impact, the fireball would have penetrated the 800 to 1000 meters of water and reaching the sea floor. After 4 seconds, the impactor would have vaporised completely creating a transient crater approximately 1 km deep. After 30 seconds, the sea floor would have rebounded to a depth of about 400 meters below the previous floor level already. Within 2-3 minutes after impact, the entire process of refilling with water and rebound of the seafloor would mostly have been completed. Shock waves from the impact would be equivalent to a magnitude 6.5 or 7 earthquake, which would likely trigger underwater landslides around the region. A train of tsunami waves would have formed, which affected coastlines rather randomly due to amplitude magnification.
The theory is therefore based on the evidence that the resulting tsunami damage was largest on Carlsö and nearby Gilles Villes, reaching about 400 meters in height. Since the Julian Sea basin was home to the trade monopoly of the Tsuki Integrality, all their ports, facilities and adjacent agricultural lands would have been destroyed as an immediate result of the disaster.
The impact in this region with many volcanoes contributed to an episode of large volcanic activity lasting several years and affecting volcanoes several hundreds of kilometers away. This volcanic episode has been documented well in local history. The effect of the immediate impact and the resulting volcanic eruptions was a long period of worldwide cooling, especially during the winters of 7120 to 7123. Failed harvests and resulting famines have been documented worldwide during this episode.
But the effect was most severe in the Julian Sea region itself. Remaining Tsuki populations or strongholds with a mixed population were unable to survive with the trading patterns that formed the basis of the Integrality now gone. The society's remaining infrastructure was ill-equipped to deal with the sudden and prolonged environmental challenges, since the vast majority of the ruling and trading classes had died in the immediate aftermath of the disaster. The Tsuki society's sophisticated administrative systems collapsed and the coordinated authority disintegrated. The remaining population faced such dire circumstances that recording history became a secondary concern. This explains the lack of local written sources for such a vast catastrophic event.
Supportive evidence
Even though an impact crater has not been identified yet, the meteor impact theory is the most established one in current science. This thanks to a number of geological and archaeological finds.
Between 7625 and 7685, in about 20-25 locations evidence of large and mega tsunami's have been found in the geological strata. Most of these sites are within Sokoku, but in 7665 the first geological evidence of recent maritime sediments have been found outside that nation, documented by geologists from Einhafan. However, in some other locations such evidence could not be found. Many of the geomorphological evidence could not be dated properly and are therefore impossible to link to exactly the Julian Event. Also, evidence of a thin layer of breccia and sediments usually associated with ejecta have been found exactly underneath many layers of volcanic related pummice sediments in at least 12 locations, of which 2 outside Sokoku.
The finding of the remains of a sailing ship of an unknown design at a height of about 120 m above seal level on the Sokokan island of Ruha, off the coast of Kotonoh, clearly supports the evidence for major tsunamis. Dendrochronology dated the southern Altaian continental wood to the latter half of the 71st century.
Geologists also investigated the massive chevron dunes located along the southern coast of Shaaniaah. The largest of these dunes rise up to about 200 meters above sea level and are nearly 40 kilometers long. Directly inland from the dunes, there is evidence of massive transport of sediments, referred to as tsunami run-ups, which reach nearly 50 km inland. Previously, it was assumed that the dunes were formed by wind, but the chevron dunes are not oriented in the direction of the prevailing wind. The dunes contain marine shells mixed with sand, along with large carbonate rocks 50 cm in diameter, which cannot be carried by winds. The dunes also contain an abundance of intact microscopic marine fossils. Moreover, the sediments in the chevrons are composed of deep ocean microfossils and impact spherules (formed when small droplets of molten and vaporised rock in the plume condense), to which are adhered particles of iron, nickel and chromium. These elements are common in chondritic meteors but rare in Gotha's crust.
Evidence reconstructed from written records, both from accounts from hundreds of kilometers away as well as the scarce amount of scrolls attributed to the Tsuki, are rather inconclusive about the exact cause of the disaster. No clear descriptions of any events clearly linked to a meteor impact have been found, or such accounts could be translated or interpreted in many ways. Even the most direct reference towards a tsunami event in 7118 or 7119, as documented in the biographies of Exemplar Gacha, do not take up the cause of such a mega wave. However, the conclusion that the Julian sea did suffer a catastrophic event has been puzzled together by combining several written sources from that era.
Alternative theory: major volcanic explosion
The original hypothesis of a Julian Event pointed out the volcanic island of Raguna Roku as the most likely source of the disaster. It has been established that the volcano did erupt around this time and that the island lost its entire population and vegetation in the event. Scientists however disagree if the Roku eruption is a result of the supposed meteor impact, or the main cause of the catastrophic event that destroyed much of civilisation around the Julian Sea.
The magnitude of the eruption, particularly the submarine pyroclastic flows, has been difficult to estimate because the majority of the erupted products were deposited in the sea. Together, these challenges result in considerable uncertainty regarding the volume of the eruption. The eruption might generated 35 to 50 m high tsunamis that devastated coastlines. This is however not nearly as high as archaeological evidence of 100 meter high tsunami's taking place on remote coastlines like southern mainland Altaia.
Alternative theory: submerged landslide
Since the volcanic eruption of Roku could not (yet) explain the magnitude of the disaster, the hypothesis of a submerged landslide was formulated. This should have taken place on the northeastern slope of the volcanic complex, facing current day Mirei state, in order to explain the highest tsunami's impacting on that particular coast. Even though some evidence of a submerged slide has been found in this particular region, it has been impossible to set a date on that particular event. Even in this case, it is fully well possible that a landslide occurred in direct relation to the meteor impact itself, the resulting volcanic activity or the supervolcano explosion on its own. It is even possible that a tsunami caused by a meteor strike resulted in a coastal landslide, which would have created a more local tsunami. In case of such a tsunami complex it is relatively easy to explain very high peak waves slamming certain coasts.
Aftermath
The catastrophic event resulted in the sudden disappearance of the Tsuki Integrality as a trade monopoly, defensive cooperation and culture around the Julian Sea. The following failed harvests resulted in the remaining structures of society being broken down to an almost prehistoric level. As a result, nearby cultures, civilisations and nation states started expanding their area of influence. But the most lasting historical impact was the arrival of Anarian explorers and settlers, who found a region with a lack of defensive capabilities or government structures. It is generally accepted these days that the event has resulted in very beneficial circumstances for Anarian colonies to be established and then extended into colonies and larger colonial holdings. The five century long colonial history of the region might never have taken place without the catastrophe that created a cultural and political vacuum in the region.