The first shock started at 8 in the morning and lasted between 80 and 90 seconds.
It began very gently, became strong, and was a little less strong when it ended. The
ground immediately around us seemed to shake violently like a cradle rocking. Only
rarely do earthquakes last so long and have such strange motions. The water standing
in pools was thrown about and splashed over their edges. The water in the ditches
around the village was also thrown about and over the banks, and from being crystal
clear became thick with mud. Dogs howled and the beasts stood like statues while
flocks of startled birds flew shrieking from south to north as if moved by an invisible
force. The people fled into the streets; many could not stand and in terror fell to their
knees and cried out, "Lord have mercy". The houses cracked and if they did not have
light roof's of asphalt would have fallen in, which would have made this earthquake as
destructive as the one in San Salvador in Central America. Many people were nause-
ated. Along the banks of the creek near here the earthquake has produced long open
cracks of varying width. A few minutes after 8 there was another earthquake, which
lasted for a short time. At 11 at night there was a third shock which lasted 4 seconds;
during the night three more were felt, making a total of six that were noticed by most
people. There is also another phenomenon. From the first shock at 10 A.M. until five
P.M. the earth has been moving constantly, though it has required close attention to
notice this. There have certainly been more than a few periods, up to 20 minutes long,
of almost imperceptible earthquakes. It seemed as though the Earth, tired of suffering
our sins, was shaking herself free of us as birds shake off' what disturbs their feathers.

The day before the shock the clouds collided with each other, as if in aerial combat.
One lady, seeing this, predicted that something was about to happen in the earth. Even
the cocks' crows have seemed prophetic. For the last four or six weeks we have seen
a new kind of white and dusty fog that has never appeared before. Some people who
have spent time in it say that it stays in one's hair like flour or ashes. If I am not
mistaken, some silent air currents have been passing over us, which have influenced
even if they have not caused these earthquakes.

We hope these phenomena will be studied by naturalists. They should bear in mind
that last winter (1855-56) there was so little rain that the fields were not covered with
vegetation, and that this winter was very late, the first rains not falling until December
28 instead of October or November as is usual. There is reason to believe that in this
region the Earth's surface is underlain by layers, or perhaps deep streams, or great
pits of asphalt, as is shown by the springs and seeps of this mineral found in this area.
The earthquakes began after 12 days of rain (counting from December 28th to the 8th
of this month), as if they had been produced by an alteration of the elements, the long
drought being ended by the rains.

On the night of the 9th and 10th, three more shocks were felt, though all were brief.
The aspect of things remained threatening.

http://www.youtube.com/watch?v=1MFzcl-kZHo
"Sophie the dog senses earthquake in Eureka at the Times-Standard"

A quick way to determine the distance from a location to the origin of a seismic wave less than 200 km away is to take the difference in arrival time of the P wave and the S wave in seconds and multiply by 8 kilometers per second. Modern seismic arrays use more complicated earthquake location techniques