Abstract
It has long been recognized that earthquakes change the stress in the upper crust around the fault rupture and can influence the behaviour of neighbouring faults and volcanoes. Rapid estimates of these stress changes can provide the authorities managing the post-disaster situation with valuable data to identify and monitor potential threads and to update the estimates of seismic and volcanic hazard in a region. Here we propose a methodology to evaluate the potential influence of an earthquake on nearby faults and volcanoes and create easy-to-understand maps for decision-making support after large earthquakes. We apply this methodology to the Mw 7.8, 2016 Ecuador earthquake. Using Sentinel-1 Interferometric Synthetic Aperture Radar (InSAR) and continuous GPS data, we measure the coseismic ground deformation and estimate the distribution of slip over the fault rupture. We also build an alternative source model using the Global Centroid Moment Tensor (CMT) solution. Then we use these models to evaluate changes of static stress on the surrounding faults and volcanoes and produce maps of potentially activated faults and volcanoes. We found, in general, good agreement between our maps and the seismic and volcanic events that occurred after the Pedernales earthquake. We discuss the potential and limitations of the methodology.
Highlights
Earthquakes influence the crust around them, changing the stress state and influencing the faults and volcanoes in the vicinity [1,2]
Results of the Static Stress Analysis We have produced 8 maps of static stress changes corresponding to the 6 crustal faults families, the subduWctieohnaivneteprrfoadcue,cethde8amvaeprasgoef ssttarteiscsstirnecsrsecmhaenngtetsakcoinrrgesipnotondaicncgotuontthael6l tchruesftaaul flat ufaltms fialimesiliaens,d the EcuadtthhoeeriEasuncubvdaodulocctraiioannnoevinsotle(cFrafinagcoueer,set(hF6ei)g.auWvreeera6hg).aeWvseterpehsrasovdienupccrreeomdduetnhcetedtsatakhmienegsasimnetteoosafectmcoofaupmnsat upaslsliunthsgientgfhaetuhlGet lfGoalmboabillaieClsCMaMnTTdfocal mechafonciasml mwecithhanruispmtuwreithdirmupentusrioendsimobentasiinoends ofrbotmain[e4d9]freommp[i4ri9c]aelmreplairtiicoanlsre(Slautipopnlsem(SuenptpalreymFenigtaurrye S5)
We present a methodology to evaluate earthquake-induced effects on neighbouring faults and volcanoes and create understandable maps addressed to decision-makers managing the post-earthquake situation
Summary
Earthquakes influence the crust around them, changing the stress state and influencing the faults and volcanoes in the vicinity [1,2]. The Coulomb failure stress criterion is one of the most common analyses used to explain fault interactions and seismological observations after earthquakes, such as aftershocks distribution (e.g., [7,8]) These procedures are commonly used today by the academic community, the transfer of these results to the authorities managing the post-earthquake situation is not straightforward and its usefulness is reduced in practice. We propose a methodology to evaluate the potential influence of an earthquake on nearby faults and volcanoes and create easy-to-understand maps for decision-making support after an earthquake We apply this methodology to the Mw 7.8, 2016 Ecuador earthquake that occurred on 16 April 2016 at 23:58:36.980 UTC (https://earthquake.usgs.gov/earthquakes/eventpage/us20005j32# origin). Using Sentinel-1 SAR and continuous GPS data, we measure the coseismic ground deformation and estimate the distribution of slip We use this model to calculate changes of stress on the surrounding faults and volcanoes. We discuss the potential and limitations of the methodology and the lessons learnt from discussion with local authorities (the Geological Survey of Ecuador, INIGEMM)
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