P-Wave Velocity Tomography from Local Earthquakes in Western Mexico

Ochoa-Chávez, Juan A.; Escudero, C. R.; Núñez-Cornũ, F. J.; Bandy, William L.

doi:10.1007/s00024-015-1183-x

Cited by 12 publications

(4 citation statements)

References 95 publications

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“…Many authors have extensively analyzed these data, using different techniques. The travel times of body waves from regional seismicity were inverted by Ochoa-Chávez et al (2015) to derive the crustal structure beneath the entire Rivera region. Data from the same networks were used to perform teleseismic tomography inversion (Yang et al, 2009), providing information on the seismic structures down to the upper mantle.…”

Section: Introductionmentioning

confidence: 99%

Fault‐Associated Magma Conduits Beneath Volcán de Colima Revealed by Seismic Velocity and Attenuation Tomography Studies

et al. 2019

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We present the results of tomographic studies using seismic velocity and attenuation in the area of the Colima Volcanic complex (CVC). Our dataset comprises body waves from local earthquakes recorded by the temporary seismic stations of the CODEX network in the Colima area and a few stations of the regional Mapping the Rivera Subduction Zone (MARS) networks, both deployed in 2006–2008. We obtain three‐dimensional distributions of seismic velocities and attenuation in the crust beneath the CVC area. At shallow depths, we observe a large negative anomaly to the south of CVC, coinciding with the location of the Central Colima Graben. This anomaly may represent debris avalanche deposits, as well as shallow magma reservoirs feeding the eruptions of the presently active Volcán de Colima. In contrast, the volcano edifice of Nevado de Colima, which is built of rigid igneous rocks, is associated with high‐velocity and low‐attenuation anomalies at shallow depths. In the deeper section, a major anomaly with high Vp/Vs, low Vs, and high S wave attenuation corresponds to the location of the regional Tamazula fault. As this represents a mechanically weakened zone of the crust, it may form the pathway that feeds CVC. Both velocity and attenuation models show that the fault‐associated conduit brought magma from the mantle through the lower crust to a depth of 15 km. Then, a light fraction of magma may continue to ascend, forming shallow reservoirs beneath the southern flank of CVC.

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Section: Introductionmentioning

confidence: 99%

Fault‐Associated Magma Conduits Beneath Volcán de Colima Revealed by Seismic Velocity and Attenuation Tomography Studies

et al. 2019

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“…Volcán de Colima (Mexico) and the surrounding Colima Volcanic Complex were imaged using both LET (Ochoa-Chávez et al, 2016;Watkins et al, 2018;Sychev et al, 2019) and SWT (Spica et al, 2014;Escudero and Bandy, 2017;Spica et al, 2017). All these studies found evidence for low seismic velocities in the crust beneath Colima at depth of about 10 km-25 km, although depth ranges from each study differ.…”

Section: Colimamentioning

confidence: 99%

Advances in seismic imaging of magma and crystal mush

et al. 2022

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Seismic imaging methods have provided detailed three-dimensional constraints on the physical properties of magmatic systems leading to invaluable insight into the storage, differentiation and dynamics of magma. These constraints have been crucial to the development of our modern understanding of magmatic systems. However, there are still outstanding knowledge gaps resulting from the challenges inherent in seismic imaging of volcanoes. These challenges stem from the complex physics of wave propagation across highly heterogeneous low-velocity anomalies associated with magma reservoirs. Ray-based seismic imaging methods such as travel-time and surface-wave tomography lead to under-recovery of such velocity anomalies and to under-estimation of melt fractions. This review aims to help the volcanologist to fully utilize the insights gained from seismic imaging and account for the resolution limits. We summarize the advantages and limitations of the most common imaging methods and propose best practices for their implementation and the quantitative interpretation of low-velocity anomalies. We constructed and analysed a database of 277 seismic imaging studies at 78 arc, hotspot and continental rift volcanoes. Each study is accompanied by information about the seismic source, part of the wavefield used, imaging method, any detected low-velocity zones, and estimated melt fraction. Thirty nine studies attempted to estimate melt fractions at 22 different volcanoes. Only five studies have found evidence of melt storage at melt fractions above the critical porosity that separates crystal mush from mobile magma. The median reported melt fraction is 13% suggesting that magma storage is dominated by low-melt fraction crystal mush. However, due to the limits of seismic resolution, the seismological evidence does not rule out the presence of small (<10 km3) and medium-sized (<100 km3) high-melt fraction magma chambers at many of the studied volcanoes. The combination of multiple tomographic imaging methods and the wider adoption of methods that use more of the seismic wavefield than the first arriving travel-times, promise to overcome some of the limitations of seismic tomography and provide more reliable constraints on melt fractions. Wider adoption of these new methods and advances in data collection are needed to enable a revolution in imaging magma reservoirs.

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“…A series of body-wave tomographic studies used teleseisms (Yang et al, 2009) , regional (Ochoa-Chávez et al, 2016) , and local earthquakes (Sychev et al, 2019) to image the crust down to the upper mantle. Besides the velocity structure under the CVC, Sychev (2019) notably estimated the seismic attenuation in the region.…”

Section: Introductionmentioning

confidence: 99%