The Great Vallar Impact

Background

In the year 702 AoAM, the world was rocked by a catastrophic collision with a comet, which made groundfall in the Sea of Vallar, giving the event its name.
For many centuries, the object, a medium-period Halley-type Comet, known by some as The Skydancer, had been observed by stargazers across Altea. Ironically, it was often seen as an omen of good fortune, making a regular return to the skies of Altea once every thirty-four years.
The Skydancer was composed of an irregularly shaped nucleus, approximately two and a half kilometers in length, of rock, ice, dust and frozen gases.
In the year leading up to the impact, many of those blessed with second sight, be it arcane or divine in nature, began to warn of an upcoming catastrophe. Their predictions were of such variety and of such a vague nature, that they were all but ignored by those in power. Again, in an ironic twist of fate, during this era, many arcane practitioners were in possession of abilities which might have been of use in protecting against the oncoming disaster (The era was, after all, known as The Age of Arcane Might). Most, however, put little stock in the doomsayers, or were too wrapped up in their own machinations to take the warnings seriously.

The Event

In the early morning hours of a late-Spring day, The Skydancer's orbit finally intersected the path of Altea, screaming through the upper layers of the planet's atmosphere at a speed of roughly eleven kilometers per second.
As the comet descended through the atmosphere, it began to break up, which did lessen the final impact force somewhat, and as such it was not an extinction-level event. Fragments of the comet were scattered in a trail, thousands of miles long, across the continent of Aetrun as it made its final, flaming path through the skies of Altea. Many of these fragments would combust in airburst events during their descents, causing destruction across the continent.
The initial result of the core impact was a massive tidal wave, which swept outward from the impact point, only forty miles from the shore. Fortunately for the people of Aetrun, the comet had descended on an north-westerly trajectory, meaning that the main thrust of the tidal wave was directed away from the populous continent. It would by no means go unscathed, however, as large sections of the western coastline of the continent were still swamped by smaller tsunamis. A large number of coastal settlements were immediately lost or devastated beyond repair.

Long-Term Effects

The impact was to be the catalyst for a series of events which would reshape the world over the following decades.
The people of the coastal Elven city of Ión-Tarnis were able to protect themselves through magic from the inital tsunamis caused by the impact, but the seismic instability on the sea bed which followed the impact would lead to the eventual subsidence of the island on which the city stood, and the loss of the city beneath the ocean.
The same seismic instability would cause techtonic sub-plate movements and the opening of undersea along a section of more southern section of coastline. This would result in a section of the Silverpeak Mountains subsiding by approximately fifty metres. Valleys which had once been home to many hardy communities suddenly found themselves underwater as the newly released seawaters flooded in. In the long term, this led to the mountainside dwarven mining town of Steamhold also gaining a respectable fishing industry.
A period of much increased volcanic activity was observed for several decades after the event.
While the primary impact occured in the Sea of Vallar, secondary impacts of comet fragments across the continental landmass of Aetrun, and the resulting volcanism from the event as a whole, would lead to large amounts of dust being thrown into the planet's atmosphere. This caused the so-called 'Decade of Winter', as less sunlight would reach the planet's surface.
Perhaps the most cataclysmic result of the comet's impact was not of a natural at all, however. The impact, although predicted by some, had largely taken those in power by surprise. The sheer destruction caused by the event shocked them, and a conclave of some of the most powerful magic users of the age was convened to decide how to prevent such disasters from happening in the future. The solution which they decided upon, after much deliberation and debate, was the conjuration of an arcane shield to envelop the entire planet of Altea, which was to protect the planet from harm and safeguard the people from further destruction from above.
Preparations for this great undertaking would take several years, but finally in 717 AoAM, all was ready, and the conclave convened at a specially constructed spire in the centre of Aetrun to carry out their ritual.
Nobody knows quite what went wrong with the ritual itself, but while still in its nascent stages, the newly created magical shield collapsed; the energies used in its conjuration pouring back into the spire, obliterating it and all its inhabitants in an instant, and releasing an unstoppable wave of magical destruction across thousands of square-kilometers of Aetrun. This event created the warped magical wasteland known as The Auric Wastes, and as such is known as The Auric Sundering.

Type

Natural