Seismicity patterns during a period of inflation at Sierra Negra volcano, Galápagos Ocean Island Chain

Lindsey Davidge, Cynthia Ebinger, Mario Ruiz, Gabrielle Tepp, Falk C Amelung, Dennis Geist, Dustin Coté, Juan Anzieta

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

Basaltic shield volcanoes of the western Galápagos islands are among the most rapidly deforming volcanoes worldwide, but little was known of the internal structure and brittle deformation processes accompanying inflation and deflation cycles. A 15-station broadband seismic array was deployed on and surrounding Sierra Negra volcano, Galápagos from July 2009 through June 2011 to characterize seismic strain patterns during an inter-eruption inflation period and to evaluate single and layered magma chamber models for ocean island volcanoes. We compare precise earthquake locations determined from a 3D velocity model and from a double difference cluster method. Using first-motion of P-arrivals, we determine focal mechanisms for 8 of the largest earthquakes (ML≤1.5) located within the array. Most of the 2382 earthquakes detected by the array occurred beneath the broad (∼9 km-wide) Sierra Negra caldera, at depths from surface to about 8 km below sea level. Although outside our array, frequent and larger magnitude (ML≤3.4) earthquakes occurred at Alcedo and Fernandina volcano, and in a spatial cluster beneath the shallow marine platform between Fernandina and Sierra Negra volcanoes. The time-space relations and focal mechanism solutions from a 4-day long period of intense seismicity June 4–9, 2010 along the southeastern flank of Sierra Negra suggests that the upward-migrating earthquake swarm occurred during a small volume intrusion at depths 5–8 km subsurface, but there was no detectable signal in InSAR data to further constrain geometry and volume. Focal mechanisms of earthquakes beneath the steep intra-caldera faults and along the ring fault system are reverse and strike-slip. These new seismicity data integrated with tomographic, geodetic, and petrological models indicate a stratified magmatic plumbing system: a shallow sill beneath the large caldera that is supplied by magma from a large volume deeper feeding system. The large amplitude inter-eruption inflation of the shallow sill beneath the Sierra Negra caldera is accompanied by only very small magnitude earthquakes, although historical records indicate that larger magnitude earthquakes (Mw <6) occur during eruptions, trapdoor faulting episodes without eruptions, and large volume flank intrusions.

Original languageEnglish (US)
Pages (from-to)169-179
Number of pages11
JournalEarth and Planetary Science Letters
Volume462
DOIs
StatePublished - Mar 15 2017

Fingerprint

Volcanoes
inflation
volcanoes
seismicity
Earthquakes
oceans
caldera
earthquakes
volcano
earthquake magnitude
volcanic eruption
focal mechanism
calderas
ocean
earthquake
volcanic eruptions
sill
shield volcano
earthquake swarm
intrusion

Keywords

  • Galapagos
  • ocean island volcano
  • seismicity

ASJC Scopus subject areas

  • Geophysics
  • Geochemistry and Petrology
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science

Cite this

Seismicity patterns during a period of inflation at Sierra Negra volcano, Galápagos Ocean Island Chain. / Davidge, Lindsey; Ebinger, Cynthia; Ruiz, Mario; Tepp, Gabrielle; Amelung, Falk C; Geist, Dennis; Coté, Dustin; Anzieta, Juan.

In: Earth and Planetary Science Letters, Vol. 462, 15.03.2017, p. 169-179.

Research output: Contribution to journalArticle

Davidge, Lindsey ; Ebinger, Cynthia ; Ruiz, Mario ; Tepp, Gabrielle ; Amelung, Falk C ; Geist, Dennis ; Coté, Dustin ; Anzieta, Juan. / Seismicity patterns during a period of inflation at Sierra Negra volcano, Galápagos Ocean Island Chain. In: Earth and Planetary Science Letters. 2017 ; Vol. 462. pp. 169-179.
@article{956a2694b65240e98dd1c096fd0b9bbf,
title = "Seismicity patterns during a period of inflation at Sierra Negra volcano, Gal{\'a}pagos Ocean Island Chain",
abstract = "Basaltic shield volcanoes of the western Gal{\'a}pagos islands are among the most rapidly deforming volcanoes worldwide, but little was known of the internal structure and brittle deformation processes accompanying inflation and deflation cycles. A 15-station broadband seismic array was deployed on and surrounding Sierra Negra volcano, Gal{\'a}pagos from July 2009 through June 2011 to characterize seismic strain patterns during an inter-eruption inflation period and to evaluate single and layered magma chamber models for ocean island volcanoes. We compare precise earthquake locations determined from a 3D velocity model and from a double difference cluster method. Using first-motion of P-arrivals, we determine focal mechanisms for 8 of the largest earthquakes (ML≤1.5) located within the array. Most of the 2382 earthquakes detected by the array occurred beneath the broad (∼9 km-wide) Sierra Negra caldera, at depths from surface to about 8 km below sea level. Although outside our array, frequent and larger magnitude (ML≤3.4) earthquakes occurred at Alcedo and Fernandina volcano, and in a spatial cluster beneath the shallow marine platform between Fernandina and Sierra Negra volcanoes. The time-space relations and focal mechanism solutions from a 4-day long period of intense seismicity June 4–9, 2010 along the southeastern flank of Sierra Negra suggests that the upward-migrating earthquake swarm occurred during a small volume intrusion at depths 5–8 km subsurface, but there was no detectable signal in InSAR data to further constrain geometry and volume. Focal mechanisms of earthquakes beneath the steep intra-caldera faults and along the ring fault system are reverse and strike-slip. These new seismicity data integrated with tomographic, geodetic, and petrological models indicate a stratified magmatic plumbing system: a shallow sill beneath the large caldera that is supplied by magma from a large volume deeper feeding system. The large amplitude inter-eruption inflation of the shallow sill beneath the Sierra Negra caldera is accompanied by only very small magnitude earthquakes, although historical records indicate that larger magnitude earthquakes (Mw <6) occur during eruptions, trapdoor faulting episodes without eruptions, and large volume flank intrusions.",
keywords = "Galapagos, ocean island volcano, seismicity",
author = "Lindsey Davidge and Cynthia Ebinger and Mario Ruiz and Gabrielle Tepp and Amelung, {Falk C} and Dennis Geist and Dustin Cot{\'e} and Juan Anzieta",
year = "2017",
month = "3",
day = "15",
doi = "10.1016/j.epsl.2016.12.021",
language = "English (US)",
volume = "462",
pages = "169--179",
journal = "Earth and Planetary Sciences Letters",
issn = "0012-821X",
publisher = "Elsevier",

}

TY - JOUR

T1 - Seismicity patterns during a period of inflation at Sierra Negra volcano, Galápagos Ocean Island Chain

AU - Davidge, Lindsey

AU - Ebinger, Cynthia

AU - Ruiz, Mario

AU - Tepp, Gabrielle

AU - Amelung, Falk C

AU - Geist, Dennis

AU - Coté, Dustin

AU - Anzieta, Juan

PY - 2017/3/15

Y1 - 2017/3/15

N2 - Basaltic shield volcanoes of the western Galápagos islands are among the most rapidly deforming volcanoes worldwide, but little was known of the internal structure and brittle deformation processes accompanying inflation and deflation cycles. A 15-station broadband seismic array was deployed on and surrounding Sierra Negra volcano, Galápagos from July 2009 through June 2011 to characterize seismic strain patterns during an inter-eruption inflation period and to evaluate single and layered magma chamber models for ocean island volcanoes. We compare precise earthquake locations determined from a 3D velocity model and from a double difference cluster method. Using first-motion of P-arrivals, we determine focal mechanisms for 8 of the largest earthquakes (ML≤1.5) located within the array. Most of the 2382 earthquakes detected by the array occurred beneath the broad (∼9 km-wide) Sierra Negra caldera, at depths from surface to about 8 km below sea level. Although outside our array, frequent and larger magnitude (ML≤3.4) earthquakes occurred at Alcedo and Fernandina volcano, and in a spatial cluster beneath the shallow marine platform between Fernandina and Sierra Negra volcanoes. The time-space relations and focal mechanism solutions from a 4-day long period of intense seismicity June 4–9, 2010 along the southeastern flank of Sierra Negra suggests that the upward-migrating earthquake swarm occurred during a small volume intrusion at depths 5–8 km subsurface, but there was no detectable signal in InSAR data to further constrain geometry and volume. Focal mechanisms of earthquakes beneath the steep intra-caldera faults and along the ring fault system are reverse and strike-slip. These new seismicity data integrated with tomographic, geodetic, and petrological models indicate a stratified magmatic plumbing system: a shallow sill beneath the large caldera that is supplied by magma from a large volume deeper feeding system. The large amplitude inter-eruption inflation of the shallow sill beneath the Sierra Negra caldera is accompanied by only very small magnitude earthquakes, although historical records indicate that larger magnitude earthquakes (Mw <6) occur during eruptions, trapdoor faulting episodes without eruptions, and large volume flank intrusions.

AB - Basaltic shield volcanoes of the western Galápagos islands are among the most rapidly deforming volcanoes worldwide, but little was known of the internal structure and brittle deformation processes accompanying inflation and deflation cycles. A 15-station broadband seismic array was deployed on and surrounding Sierra Negra volcano, Galápagos from July 2009 through June 2011 to characterize seismic strain patterns during an inter-eruption inflation period and to evaluate single and layered magma chamber models for ocean island volcanoes. We compare precise earthquake locations determined from a 3D velocity model and from a double difference cluster method. Using first-motion of P-arrivals, we determine focal mechanisms for 8 of the largest earthquakes (ML≤1.5) located within the array. Most of the 2382 earthquakes detected by the array occurred beneath the broad (∼9 km-wide) Sierra Negra caldera, at depths from surface to about 8 km below sea level. Although outside our array, frequent and larger magnitude (ML≤3.4) earthquakes occurred at Alcedo and Fernandina volcano, and in a spatial cluster beneath the shallow marine platform between Fernandina and Sierra Negra volcanoes. The time-space relations and focal mechanism solutions from a 4-day long period of intense seismicity June 4–9, 2010 along the southeastern flank of Sierra Negra suggests that the upward-migrating earthquake swarm occurred during a small volume intrusion at depths 5–8 km subsurface, but there was no detectable signal in InSAR data to further constrain geometry and volume. Focal mechanisms of earthquakes beneath the steep intra-caldera faults and along the ring fault system are reverse and strike-slip. These new seismicity data integrated with tomographic, geodetic, and petrological models indicate a stratified magmatic plumbing system: a shallow sill beneath the large caldera that is supplied by magma from a large volume deeper feeding system. The large amplitude inter-eruption inflation of the shallow sill beneath the Sierra Negra caldera is accompanied by only very small magnitude earthquakes, although historical records indicate that larger magnitude earthquakes (Mw <6) occur during eruptions, trapdoor faulting episodes without eruptions, and large volume flank intrusions.

KW - Galapagos

KW - ocean island volcano

KW - seismicity

UR - http://www.scopus.com/inward/record.url?scp=85009758640&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85009758640&partnerID=8YFLogxK

U2 - 10.1016/j.epsl.2016.12.021

DO - 10.1016/j.epsl.2016.12.021

M3 - Article

AN - SCOPUS:85009758640

VL - 462

SP - 169

EP - 179

JO - Earth and Planetary Sciences Letters

JF - Earth and Planetary Sciences Letters

SN - 0012-821X

ER -