Seismic, Volcanic, and Geodetic Networks in Ecuador: Building Capacity for Monitoring and Research

Alvarado, Alexandra; Ruiz, Mario; Mothes, Patricia; Yépes, Hugo; Segovia, M.; Vaca, Mayra; Ramos, Cristina; Enriquez, W.; Ponce, Gabriela; Jarrín, Paúl; Aguilar, Jorge; Acero, Wilson; Vaca, Sandro; Singaucho, Juan Carlos; Pacheco, Daniel; Cordova, A.

doi:10.1785/0220170229

Cited by 46 publications

(30 citation statements)

References 9 publications

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“…Seismic data were recorded by the permanent monitoring network of the IGEPN and two temporary deployments. Station GS09 of the SIGNET deployment (operational between late 2009 and 2011) 35 and station VCH1 (a Trillium compact 120; operational since 2012) of the IGEPN permanent network 39 were both installed at the same site close to the north rim of the caldera (Fig. 1 ).…”

Section: Methodsmentioning

confidence: 99%

Caldera resurgence during the 2018 eruption of Sierra Negra volcano, Galápagos Islands

et al. 2021

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Recent large basaltic eruptions began after only minor surface uplift and seismicity, and resulted in caldera subsidence. In contrast, some eruptions at Galápagos Island volcanoes are preceded by prolonged, large amplitude uplift and elevated seismicity. These systems also display long-term intra-caldera uplift, or resurgence. However, a scarcity of observations has obscured the mechanisms underpinning such behaviour. Here we combine a unique multiparametric dataset to show how the 2018 eruption of Sierra Negra contributed to caldera resurgence. Magma supply to a shallow reservoir drove 6.5 m of pre-eruptive uplift and seismicity over thirteen years, including an Mw5.4 earthquake that triggered the eruption. Although co-eruptive magma withdrawal resulted in 8.5 m of subsidence, net uplift of the inner-caldera on a trapdoor fault resulted in 1.5 m of permanent resurgence. These observations reveal the importance of intra-caldera faulting in affecting resurgence, and the mechanisms of eruption in the absence of well-developed rift systems.

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Section: Methodsmentioning

confidence: 99%

Caldera resurgence during the 2018 eruption of Sierra Negra volcano, Galápagos Islands

et al. 2021

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“…S3 shows the depth distribution of earthquakes in the Quito area, using the IG-EPN instrumental earthquake catalogue (https://www.igepn.edu.ec/red-nacional-de-s ismografos). The IG-EPN earthquake catalogue covers the 2011-2018 period using the data from the national Ecuadorian permanent network (Alvarado et al 2018). When considering earthquakes with magnitude ML above 2, the depth distribution is confined within the first 10 km (Fig.…”

Section: Comparison With the Seismicity Depth Distributionmentioning

confidence: 99%

Geodetic evidence for shallow creep along the Quito fault, Ecuador

Mariniere

Nocquet

Beauval

et al. 2019

Geophysical Journal International

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SUMMARY Quito, the capital city of Ecuador hosting ∼2 million inhabitants, lies on the hanging wall of a ∼60-km-long reverse fault offsetting the Inter-Andean Valley in the northern Andes. Such an active fault poses a significant risk, enhanced by the high density of population and overall poor building construction quality. Here, we constrain the present-day strain accumulation associated with the Quito fault with new Global Positioning System (GPS) data and Persistent Scatterer Interferometric Synthetic Aperture Radar (PS-InSAR) analysis. Far field GPS data indicate 3–5 mm yr–1 of horizontal shortening accommodated across the fault system. In the central segment of the fault, both GPS and PS-InSAR results highlight a sharp velocity gradient, which attests for creep taking place along the shallowest portion of the fault. Smoother velocity gradients observed along the other segments indicate that the amount of shallow creep decreases north and south of the central segment. 2-D elastic models using GPS horizontal velocity indicate very shallow (<1 km) locking depth for the central segment, increasing to a few kilometres south and north of it. Including InSAR results in the inversion requires locking to vary both along dip and along strike. 3-D spatially variable locking models show that shallow creep occurs along the central 20-km-long segment. North and south of the central segment, the interseismic coupling is less resolved, and data still allows significant slip deficit to accumulate. Using the interseismic moment deficit buildup resulting from our inversions and the seismicity rate, we estimate recurrence time for magnitude 6.5 + earthquake to be between 200 and 1200 yr. Finally, PS-InSAR time-series identify a 2 cm transient deformation that occurred on a secondary thrust, east of the main Quito fault between 1995 and 1997.

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“…In the wake of the mainshock, an international rapid response effort coordinated by the Instituto Geofísico at the Escuela Politécnica Nacional (IGEPN) in Quito deployed a temporary network of seismometers along the North Ecuador subduction zone (Meltzer et al, ). These temporary stations densified coastal stations of the permanent national network (RENSIG; Alvarado et al, ). Automatically detecting and locating earthquakes is an integral part of earthquake monitoring and postevent data analysis.…”

Section: Introductionmentioning

confidence: 99%

Structural Control on Megathrust Rupture and Slip Behavior: Insights From the 2016 Mw 7.8 Pedernales Ecuador Earthquake

et al. 2020

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The heterogeneous seafloor topography of the Nazca Plate as it enters the Ecuador subduction zone provides an opportunity to document the influence of seafloor roughness on slip behavior and megathrust rupture. The 2016 Mw 7.8 Pedernales Ecuador earthquake was followed by a rich and active postseismic sequence. An internationally coordinated rapid response effort installed a temporary seismic network to densify coastal stations of the permanent Ecuadorian national seismic network. A combination of 82 onshore short and intermediate period and broadband seismic stations and six ocean bottom seismometers recorded the postseismic Pedernales sequence for over a year after the mainshock. A robust earthquake catalog combined with calibrated relocations for a subset of magnitude ≥4 earthquakes shows pronounced spatial and temporal clustering. A range of slip behavior accommodates postseismic deformation including earthquakes, slow slip events, and earthquake swarms. Models of plate coupling and the consistency of earthquake clustering and slip behavior through multiple seismic cycles reveal a segmented subduction zone primarily controlled by subducted seafloor topography, accreted terranes, and inherited structure. The 2016 Pedernales mainshock triggered moderate to strong earthquakes (5 ≤ M ≤ 7) and earthquake swarms north of the mainshock rupture close to the epicenter of the 1906 Mw 8.8 earthquake and in the segment of the subduction zone that ruptured in 1958 in a Mw 7.7 earthquake.

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Seismic, Volcanic, and Geodetic Networks in Ecuador: Building Capacity for Monitoring and Research

Cited by 46 publications

References 9 publications

Caldera resurgence during the 2018 eruption of Sierra Negra volcano, Galápagos Islands

Caldera resurgence during the 2018 eruption of Sierra Negra volcano, Galápagos Islands

Geodetic evidence for shallow creep along the Quito fault, Ecuador

Structural Control on Megathrust Rupture and Slip Behavior: Insights From the 2016 Mw 7.8 Pedernales Ecuador Earthquake

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