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

Costa Blanca News (North Edition) - - NEWS - By Sa­man­tha Kett

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

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