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Hispaniola deformation map resolves strain along locked northern faults

A new deformation map of Hispaniola, the island shared by Haiti and the Dominican Republic, indicates substantial locking along northern faults. One peer-reviewed study combined ground stations and satellite radar to resolve where strain accumulates. Southern areas also showed accumulating strain, while part of a western fault may move through aseismic creep. The findings concern long-term earthquake hazard; the modeled moment budget does not specify when an earthquake occurs.

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A satellite-positioning antenna fixed to a stone survey monument, with a cable-connected protective case before green hills.

Velocities change sharply across the northern fault

A newly calculated deformation field for Hispaniola, the Caribbean island shared by Haiti and the Dominican Republic, indicates the northern fault zone called Septentrional–Oriente is largely locked. Sharp differences in ground velocities across the fault identify a band of accumulating strain. One peer-reviewed study used satellite radar to fill gaps between sparse ground stations when assessing earthquake hazard.[1]

The island lies where the Caribbean and North American plates converge obliquely. Around Haiti’s capital, Port-au-Prince, the southern belt of folds and thrust faults also shows accumulating strain. The westernmost part of the Enriquillo–Plantain Garden fault system showed a lower slip deficit; some movement there may be accommodated by aseismic creep.[1]

Ground measurements and radar form one velocity field

The researchers combined satellite-positioning velocities from 112 ground stations with observations from Sentinel-1, a radar satellite system. Three ascending and three descending radar tracks supported a three-dimensional velocity field spaced about 5 km apart. Spatially correlated atmospheric noise was modeled as well. The difference between east and north velocity components and the ground observations was about 1 mm per year.[1]

Long-term moment accumulation depends on the fault model

For the northern system, 300 years of modeled moment accumulation corresponded to approximately Mw 7.9 in event magnitude. The long-term budget depends on locking depth, fault dips and how accumulated moment is distributed among ruptures. The calculation specifies no earthquake date. Deeper locking and a backslip approach contribute to differences from earlier models. A low slip deficit on one western segment leaves the accumulated strain on nearby thrust faults relevant to regional hazard.[1]

References

  1. News sourceScientific ReportsAssessing earthquake potential and fault activity from a newly estimated high-resolution geodetic velocity field in Hispaniola
    Primary paperScientific ReportsAssessing earthquake potential and fault activity from a newly estimated high-resolution geodetic velocity field in Hispaniola
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