New fault threatens Atlantic earthquakes
A new tectonic subduction zone is believed to be evolving off the Iberian Peninsula, where Portugal has suffered devastating quakes in the past despite lying far from known fault lines
PROBABLE EPICENTRES OF MAJOR EARTHQUAKES
1
2
3
4
5
6
Year
1356
1755
1761
1931
1941
1969
1975
Magnitude
7.5
8.7
8.5
7.1
8.4
7.9
8.1
Direction of thrust
PORTUGAL
SPAIN
MOROCCO
Porto
Lisbon
1755 quake and tsunami killed thousands
Mantle brought to seafloor surface by seismic activity
Gloria Fault
Tydeman Fracture Zone
Less active
EURASIAN PLATE
AFRICAN PLATE
Gorringe Bank
Coral Patch Seamount
Horseshoe Abyssal Plain
Madeira
TODAY
Horseshoe Abyssal Plain covered in thick undisturbed sediment
1969 earthquake
30km below surface
Partially detached block “delaminates” from mantle, sinking to form major thrust fault
Coral Patch Seamount
Gorringe Bank
EURASIA
AFRICA
Upper mantle
10M YEARS AGO
Gloria
Fracture zones
Tydeman
30M YEARS FROM NOW
Eurasia plate pulled downwards
New seismically active subduction zone
Sources: Nature, BBC
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