catalogo de terremotos para america del sur catalog of earthquakes ...

148
be used with extreme caution, specially for the older events, since the correct
interpretation of imprecise descriptions is not alwayq immediate; the
discovery of new doc umental- evidence can lead to a better understanding of
the factq*. Qk ;uch is the case of tCie well known observation, in t:he form of a
poem, of J uan de Cartellan es concerning important damage in the Is]a de Cubagua
in the ii,hdle of the XVI century. Tiis was interpret d during many years
as a "deStr itiVc earthquake" but ne, documental evidence proofs wit-hout any
doubt that, ir fACt , it was a hurricane, conforming the .ouht which was raiscd
by Hoiontessus do Pa 11, cL , n 1 )15.
SpecAi care mu;t I iiad witih second-hand reports. It is pertinent to
q iote the supposed ce:tLct ion cf Caracas, enriched w.iith detailed descripticns
of the nIhr I-of vie t imp , damaged constructions, etc. given by Prof. Rockwood
in the .oo!rna ,,e_ Scielc, in 10 83, as a consequence of the destructive earthqIlake
wiici affec!. c1 [',aami and Col.omn ia on 7 September 1882. These is no
trtith in thtLht: report since it was contradicted by Natuiralist Ernst, at the ttme
livimpg in Caracas!, illa letter ptibllished in t-he fol lowing number of the
same m.g az ille Nainv such ather errors, whih need not be described, can distort
tlir, :ivai 1; ,vidence of a phenomenon for which little is known.
Sepa rat i rHp events wh icli have occurred in the last decades , Che quan­
titat ive evaluination of destruetiv eartliquakes is a result of a detailed study
of the known effects, reterring them to one of the intensity scales for
damages. Ti1C assignation oi intensities is highly subjective, so is difficult
to maintain uniformity or homogeneity of criteria concerning the severity
of the sha-king which has affected a certain area throughout many centuri es.
Nevertlii_-ss, .11 tie study of past earthquakes, unless there are instrumental
records;, th,.en ar. the only evidence known at present and it is on the basis
of such ,v idence that: some progress have been mad(e for quantitative evaluations
(Fiedler 1901) and those indicated in section 3.2.1.
MFIEThIOPS ['-lb IN 'IIE PPEfAIPXT TON OF TttF CATAILOGUE
3.1 Criteria "or the Selection of Fvent.
The princlpals criteria which were adopted for the compilation of the catalog
of Venezuela ,,ere the following:
i) Eewry event recorded instramentally for which there was, at least, date,
GMT tiie and geographic coord hates of the epicenter. Therefore, some
unrel iable evelts, of unknown magnitude or reported by only one station,
were included; however, other events, reported only by the Cajigal station
(CAC), with azimut and distance, were included. Together with the
hviocentur P:Irnmeters, allI of the known macroseismic information was
synthe:; i zd.
Because of political reasons of the epoch, the earthquake which destroyed
Caracas on 26 march 1812 w. ignored in England; the London newspaper "The
Times", of 29 Hay 1812, corrected this, publishing the stories of witnesses
in Li Guaira. These constitute very valuable testimony. (See Grases 1970).