You need to google "the year without a summer" - which will bring up a good example of what happened after one large eruption.
FYI - Lord Byron's poem "Darkness" was written just after 1816 and gives a glimpse of what fears it raised:
""I had a dream, which was not all a dream.
The bright sun was extinguish'd, and the stars
Did wander darkling in the eternal space,
Rayless, and pathless, and the icy earth
Swung blind and blackening in the moonless air;
Morn came, and went and came, and brought no day,
And men forgot their passions in the dread
Of this desolation; and all hearts
Were chill'd into a selfish prayer for light:
And they did live by watchfires - and the thrones,
The palaces of crowned kings, the huts,
The habitations of all things which dwell,
Were burnt for beacons; cities were consumed,
And men were gathered round their blazing homes
To look once more into each other's face;
Happy were those who dwelt within the eye
Of the volcanos, and their mountain-torch:
A fearful hope was all the world contain'd;
Forest were set on fire but hour by hour
They fell and faded and the crackling trunks
Extinguish'd with a crash and all was black. ""
