The Emperor purposed, on account of the Heresy of Aëtius and the Innovations in Antioch, to convene a Council at Nicomedia; but as an Earthquake took place in that City, and many other Affairs intervened, the Council was first convened at Nicæa, and afterwards at Ariminum and Seleucia. Account of Arsacius, the Confessor
Such were the events which transpired at Sirmium. It seemed at this period as if, from the fear of displeasing the emperor, the Eastern and Western Churches had united in the profession of the same doctrine. The emperor had determined upon convening a council at Nicæa to take into consideration the innovations introduced at Antioch, and the heresy of Aëtius. As Basil, however, and his party were averse to the council being held in this city, because doctrinal questions had previously been agitated there, it was determined to hold the council at Nicomedia in Bithynia; and edicts were issued, summoning the most intelligent and eloquent bishops of every nation to repair there punctually on an appointed day, so that it might be the privilege of all the priests of the state to share in the Synod and to be present at its decisions. The great number of these bishops had commenced their journey when the calamity that had come upon Nicomedia was reported, and that God had shaken the entire city to its foundations. Since the story of the destruction of the city everywhere prevailed and grew, the bishops arrested their journey; for as is usual in such cases, far more was rumored to those at a distance, than had actually occurred. It was reported that Nicæa, Perinthus, and the neighboring cities, even Constantinople, had been involved in the same catastrophe. The orthodox bishops were grieved immoderately at this occurrence; for the enemies of religion took occasion, on the overthrow of a magnificent church, to represent to the emperor that a multitude of bishops, men, women, and children fled to the church in the hope of their finding safety, and that they all perished. This report was not true. The earthquake occurred at the second hour of the day, at which time there was no assembly in the church. The only bishops who were killed were Cecropius, bishop of Nicomedia, and a bishop from the Bosphorus, and they were outside of the church when the fatal accident happened. The city was shaken in an instant of time, so that the people had not the power, even if they had the wish, to seek safety by flight; at the first experience of danger, they were either preserved, or they perished on the spot where they were standing.
It is said that this calamity was predicted by Arsacius. He was a Persian, and a soldier who was employed in tending the emperor's lions; but during the reign of Licinius he became a noted confessor, and left the army. He then went to the citadel of Nicomedia, and led the life of a monastic philosopher within its walls. Here a vision from heaven appeared to him, and he was commanded to quit the city immediately, that he might be saved from the calamity about to happen. He ran with the utmost earnestness to the church, and besought the clergy to offer supplications to God that His anger might be turned away. But, finding that far from being believed by them, he was regarded with ridicule, and as disclosing unlooked-for sufferings, he returned to his tower, and prostrated himself on the ground in prayer. Just at this moment the earthquake occurred, and many perished. Those who were spared fled into the country and the desert. And as happens in a prosperous and large city, there were fires in the brasiers and extinguishers of every house, and in the ovens of the baths, and in the furnaces of all who use fire in the arts; and when the framework fell in ruin, the flame was hemmed in by the stuff, and of course there was dry wood commingled, much of which was oily,— this served as a contribution to the rapid conflagration, and nourished the fire without stint; the flame creeping everywhere, and attaching to itself all circumjacent material, made the entire city, so to speak, one mass of fire. It being impossible to obtain access to the houses, those who had been saved from the earthquake rushed to the citadel. Arsacius was found dead in the unshaken tower, and prostrated on the ground, in the same posture in which he had begun to pray. It was said that he had supplicated God to permit him to die, because he preferred death to beholding the destruction of a city in which he had first known Christ, and practiced monastical philosophy. As I have been led to speak of this good man, it is well to mention that he was endowed by God with the power of exorcising demons and of purifying those troubled by them. A man possessed with a demon once ran through the market-place with a naked sword in his hand. The people fled from him, and the whole city was in confusion. Arsacius went out to meet him, and called upon the name of Christ, and at that name the demon was expelled, and the man restored to sanity. Besides the above, Arsacius performed many other actions beyond the power and skill of man. There was a dragon, or some other species of reptile, which had entrenched itself in a cavity of the roadside, and which destroyed those who passed by, with its breath. Arsacius went to the spot and engaged in prayer, and the serpent voluntarily crept forth from its hole, dashed its head against the ground, and killed itself. All these details I have obtained from persons who heard them stated by those who had seen Arsacius.
Source: Ecclesiastical History (New Advent)