Historical Seismograms - Evidence from the AD 2000 Izu Islands ...

2 10 D. Muiioz and A. Udias3. Evaluation of Damage and ParametersThe information collected from all sources has been used in the estimation ofintensities at 38 sites. The fact that this earthquake coincided with one period ofpestilence (1676-1685), in a certain way, has been an advantage in the evaluationof intensities. In many localities where no appreciable damage was produced, fearof the pestilence made the impression of the shock fall into a second place and theearthquake was not even mentioned in contemporary documents. It is probable thatin the absence of the plague, more attention would have been given to the earthquakeand its effects magnified in the accounts. This could have led to overestimation ofintensities in many locations. Since documents, usually reflect only serious damage,they are only found in the region near the epicenter. Felt reports which correspondto lower intensities are given only for important cities such as Madrid, Sevilla,Valladolid, etc. A list of the towns with estimated intensities is given in Table 1.The intensity map resulting from these data is shown in Figure 1. Dashed linesare used for regions with insufficient data. After much consideration maximumintensity has been estimated at VIII-IX (MSK). This estimation is lower than somepreviously given intensities for this earthquake, as mentioned above.The zone of maximum intensity covers an area of approximately 25 km radius,centered to the west of MAlaga. This zone is well documented from the informationof MLlaga and surrounding towns; we have estimated that intensity nowhere exceededVIII-IX (MSK). For example in Alhaurin el Grande, the church was totallyruined, 122 houses collapsed, 53 houses were rendered uninhabitable and the restwere heavily damaged, and 7 persons died. Although the percentage of destroyedhouses was large, construction was of very low quality everywhere, most of type Aaccording to the MSK scale. For this reason it is not definite that intensity IX wasclearly reached. In Mdlaga, where churches were more solidly built, only two ofthem suffered substantial damage (Santos MLrtires and San Juan). Areas with intensitiesVI and VII are also well documented, since the shock was strongly felt andcaused sufficient damage to be recorded in contemporary documents. One must becareful in contrasting more than one document to avoid gross errors. For instance,in one account published in Sevilla, it is said that the cathedral of Jaen suffereddamage beyond repair, however documents from Jaen itself, such as the Acts of theTable 1. List of Towns With Estimated IntensitiesIntensityVIII-IXVIIIVIIVI-VIIVIv-VIVIV111Not FeltLocalityAlhaurin el Grande, Alhaurin de la Toree, Alozaina, Benalmadena,Cartama, Coin, M&laga, Mijas, PizarraAlora, CompetaAntequera, Ecija, OsunaLucena, Ronda, V6lez-MQlagaAlcala del rio, Andujar, Carmona, Cazalla de la Sierra, Cordoba,Granada, Jaen, Mordn de la Frontera, SevillaSan Juan de Azfalrache (Aznalfarache)Jerez de la Frontera, Sanllicar la MayorCidiz, Madrid, Puerto de Santamaria, Sanllicar de Barrameda,ToledoAlmeria, ValladolidAlcala la Real, Motril