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

The Ma'laga Earthquake of 9 October 1680 211----- --/ I I I I I 1 I/-cIV/ .----?-.MadridToledoI 11..I I Ii362--0"Figure 1. Intensity map of the MAaga earthquake.I0"Chapter of the Cathedral and of the City Hall, do not mention any damage; in thesame way there is no notice of any damage to the cathedral by Galera (1977) in hisbook on architecture of Jaen. This critical assessment of the liability of the differentaccounts is very necessary in order to obtain correct values of intensity. This lackof information and of sufficient critical judgement is reflected in the intensity mappresented by Gentil and Justo (1985) for this earthquake, where some values areoverestimated and the shape of curves distorted.In Madrid the shock was strongly felt causing the bells to ring and many peopleto flee from their houses (intensity IV). The shock was also felt further north inValladolid, giving a radius of perceptibility of about 700 km. However, the totalnumber of casualties was not great, 60 dead and 150 injured. Of the dead, 42correspond within the city of Mdlaga.The area of greater damage, shown in Figure 2, is located in the Betics, a zone ofcomplex tectonics due mainly to superposition of nappes. During the Neogene, severalinterior depressions were formed (Bousquet et a[., 1978), one of them that of theGuadalhorce River to the west of Mdlaga. These depressions were later filled withNeogene and Quaternary deposits and formed autonomous structural elements. TheGuadalhorce basin is surrounded by the Alpujarride complex, formed by Paleozoicand Triassic materials, and the Malaguide complex, formed by non-metamorphicPaleozoic materials. It is well known that the epicenter of an earthquake may notcoincide with the area of maximum intensity. The instrumental epicenter is the projectionon the horizontal plane of the initial point of rupture, while location of themaximum damage depends greatly on the geometry of the fracture, local geologyand terrain conditions. However, it is a common practice to assign also epicenter