Earthquakes of 8 on Richter scale in Northern Costa 'possible'
All bar five towns in north Costa Blanca district should, by law, have emergency quake procedures in place – but none of them does, warns regional government
EARTHQUAKES of up to 8 on the Richter scale could potentially strike the Marina Alta – and yet no contingency plan is in place for the district, warns the regional government.
The Generalitat says 28 of the Marina Alta's 33 towns and villages are required by law to have emergency procedures set up, but none of them has any.
This worrying announcement has come in light of minor tremors this summer which damaged the cathedral in Benissa – yet, ironically, Benissa is not one of the 28 at-risk towns.
Geologists calculate that a total of 327 towns in the Valencia region fall within the Grade VII category on the European earthquake scale, which means they have the potential to suffer 'very damaging' sismic movements of the type which would 'cause great commotion among the population', including 'building collapse', 'falling objects' and 'serious structural damage'.
Towns in or above Grade VII are required to have plans in place to deal with earthquakes – and, in the Marina Alta, only five towns fall below this level.
Benissa, Calpe, Benitatxell, Senija and Gata de Gorgos do not need procedures set up as they are classed as Grade VI risk areas.
Vall d'Alcalá, Dénia and Pego: Quake potential similar to Indonesia and Nepal
But earth science experts say the maximum potential magnitude of a quake elsewhere in the district ranges from 7 to 8 on the Richter scale – similar to those seen in recent years in Indonesia and Nepal.
The most at-risk village is the Vall d'Alcalà, inland from Pego, with a maximum possible intensity of 8 on the Richter scale, whilst Dénia, Pego, Sagra, Tormos, the Vall d'Ebo, the Vall de Gallinera, El Ràfol d'Almúnia, Benigembla, Murla and Alcalalí could, in theory, be rocked by quakes of up to 7.5.
Ondara, Jávea, El Verger, Els Poblets, Pedreguer, Sanet i Els Negrals, Jalón, Orba, Parcent, Beniarbeig, the Vall de Laguar, Llíber, Benidoleig, Benimeli, L'Atzúvia and Forna, Teulada and Castell de Castells show a maximum magnitude potential of 7 on the Richter scale.
Should we be worried?
Just because a maximum intensity potential is calculated at 7 or 8 does not mean it will ever happen – or that it ever has, assures the regional government.
In fact, the Marina Alta has never been the scene for even moderately-scary earthquakes – unlike the Vega Baja and Vinalopó districts on the southern Costa Blanca, which are maximum-risk areas but where, in living memory, no quakes higher than about 4 and no major damage, injury or fatalities have been reported.
But the obligation for towns to have an earthquake contingency plan in place comes automatically if a tremor of at least Grade VII has ever happened within the last 500 years.
Basically, if Dénia or Pego had suffered a 7.5 earthquake in the year 1518, they would need an emergency procedure in place now.
Nothing but a number?
Richter-scale readings are not the end of the story when an earthquake's severity is measured, however. This week's tremor in Cijuela, Granada province – felt even on the Costa del Sol – registered a magnitude of 4, but as it was 12 kilometres underground, all it caused was a momentary shudder.
A 4.5-magnitude quake in Murcia a few years back generated a much more frightening and longer-lasting shudder, but practically no damage was reported, and another of the same strength in early 2006 in the Rincón de Ademuz (Valencia province) scared locals and caused a chunk of the church in Casas Bajas to fall off, but as both were a long way underground, no other damage and no injury occurred.
Meanwhile, the 5.6 quake in Lorca (Murcia) on May 11, 2011 which led to thousands of homes turning to rubble and several deaths was much nearer the surface – between one and five kilometres down – and insurance surveyors reported that most of the collapsed properties suffered from construction defects, third-rate building materials and poor workmanship.
Yet any property built in recent years will have automatically been made in line with quake-resistant regulations, which is why churches, being older, are more likely to fall down – Benissa cathedral was constructed in 1929.
Murcia and the southern Costa Blanca suffer frequent earthquakes, but the overwhelming majority pass by unnoticed.
Those which are felt tend to be roughly between 2.5 and 4, where the overall effect is similar to that of a heavy lorry passing by at high speed.
This is fairly typical of anywhere built on a fault line or on volcanic terrain: for example, Iceland suffers an average of 20 earthquakes a day, but not one has hit the headlines in living memory and few Icelandic adults can remember even feeling a tremor.
⏩ See our 'What to do when the earth shakes' special report in our Costa Living supplement this week
Repair work on Benissa cathedral after a recent earth tremor damaged the façade