_General examples of earthquake effects._—The following examples of
earthquake effects are drawn from Mallet’s account of the Neapolitan
earthquake of 1857.
At a town called Polla there was great destruction. Judging from
the fissures in the parts that remained standing it seemed that the
emergence of the shock had been more vertical in the upper part of the
town than in the lower, proving that whatever had been the angle below,
the hill had itself vibrated, which, being horizontal, had modified the
angle of the fissures.
Diano suffered but little, partly because it was well built, and partly
on account of its situation, which was such that before the shock
reached it the disturbance had to pass from beds of clay into nearly
vertically placed beds of limestone. Also a great portion of the shock
was cut off by the Vallone del Raccio to the north and north-west of
the town. Here the effects of the partial extinction of the wave on the
‘free outlaying stratum’ were visible in the masses of projected rock.
Castellucio did not suffer because its well buttressed knoll was end
on to the direction of shock, and on account of a barrier of vertical
breccia beds protecting it upon the east.
Pertosa stands on a mound. The destruction was least in the southern
part of the town. From the relation of the beds of breccia on which the
town stands, and the direction of the wave path, it is evident that the
southern part of the town received the force of the shock through a
greater thickness of the breccia beds than the other parts did.
Petina, standing on a level limestone spur jutting out from a mountain
slope, suffered nothing, whilst Anletta five miles to the south-west,
and Pertosa six miles distant, were in great part prostrated. (1) The
terrace did not vibrate, and (2) between Petina and Anletta there is
almost 6,000 feet of piled up limestone, so that any shock emergent at
a steep angle had to pass up transversely through these beds.
_Protection of buildings._—In addition to giving proper construction
to our buildings, choosing proper foundations and positions for them,
something might possibly be done to ward off the destructive effects of
an earthquake. We read that the Temple of Diana at Ephesus was built on
the edge of a marsh, in order to ward off the effect of earthquakes.
Pliny tells us that the Capitol of Rome was saved by the Catacombs,
and Elisée Reclus[36] says that the Romans and Hellenes found out that
caverns, wells, and quarries retarded the disturbance of the earth,
and protected edifices in their neighbourhood. The tower of Capua was
saved by its numerous wells. Vivenzis asserts that in building the
Capitol the Romans sunk wells to weaken the effects of terrestrial
oscillations. Humboldt relates the same of the inhabitants of San
Domingo.
Quito is said to receive protection from the numerous cañons in the
neighbourhood, whilst Lactacunga, fifteen miles distant, has often been
destroyed.
Public-domain text, read in full here on John Shaqi.
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