1. GREAT FAULTS, SMALL FAULTS AND CODES
|THE 1755 LISBON EARTHQUAKE AND TSUNAMI (8,5-8,8)
|NCSE 02 IS ONLY A STRUCTURAL CODE DESIGNED FOR EACH INDIVIDUAL PIECE OF THE SYSTEM: THE BUILDING. BUT THE REAL SCENERY OF THE SEISMIC EVENT IS ALWAYS THE CITY. THE 3D GROUND EFFECT IS NOT CONSIDERED ENOUGH IN NCSE 02, BUT IT IS STILL LESS CONSIDERED IN URBAN ORDINANCES THAT CONTEMPLATE GROUND AS A SURFACE RATHER THAN A VOLUME WITH DISCONTINUITIES, IRREGULARITIES, AND FAILURES.
|SOUTHEASTH IBERIA BIG FAULTS
|MAP OF THE PALEOSEISMICITY STUDIED IN IBERIA: ONLY THE SOUTHEAST TERRITORY AND CATALUÑA SHOW A FEW STUDIES OF THE LAST MIOCENIC-PLIOCENIC AND QUATERNARY SEISMIC ACTIVITY
An example: Lorca is on the axis of the FAM (Alhama de Murcia Fault). Both seismic movements that occurred on May 11th were very superficial (2 km depth): the first (4.5 Mw) two hours before the second (5.2 Mw) was only 3 km NE from town centre. This also explains the high number of minor events registered months after the two main events (more than 300), identified across the segments in which the FAM is divided into. This is a transcendental question because similar configurations may exist not only in the region of Murcia but also in many other regions in Southwest Europe, such as Navarra, the Basque Country, Aragón and Cataluña, in Spain and their counterparts on the North side of Pyrenees: in French Departments, Pyrenées Atlantiques and Orientaux.
|3D GEOLOGICAL STRUCTURE AND MOVING MATERIALS UNDER SOUTHEAST IBERIA
The year before the earthquakes struck Lorca, the FAM was in an inter-seismic period with no activity at all. Thus, it was quite predictable, with obvious limitations, that something was going to happen; some tectonic experts even announced it, as is the case of Professor Tomás Rodriguez (University of Cartagena). The real unexpected issue was not the earthquake itself but the top basic acceleration that was generated: 0.41g. This was more than 3 times the expected value (0.12g). There is no doubt that among other questions an amplification phenomenon happened. Are the C, k, S coefficients or the other of our capricious inventions, responsible of it? Or certainly we don't have the correct 3D mental-picture of the real nature of the ground under our feet? Is the ground under Lorca smart enough to be "aware" that its coefficients are: k=1, C=1.61, and S=1.27, or does it simply not care?