Midcrustal, Long-period Earthquakes beneath Northern California Volcanic Areas

Pitt, A. M.; Hill, David P.; Walter, S. W.; Johnson, Michael

doi:10.1785/gssrl.73.2.144

Cited by 48 publications

(40 citation statements)

References 26 publications

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“…If in contrast, the old Long Valley silicic magma chamber were still a substantial source of gas, that residual gas would be fractionated along the lines discussed by Hilton (1996) and Sorey et al (1998) and would not resemble the gas at Mammoth Mountain as closely as it does (Table 4). A basaltic source for the Mono Craters gas, as originally invoked to account for the CO 2 trapped in Mono Craters obsidians (Newman et al, 1988), would be consistent with the deep long-period seismicity proximal to the chain (Pitt et al, 2002). Two of the silicic domes near North Coulee contain mafic enclaves, in accord with basaltic magma directly beneath the silicic chamber (Kelleher and Cameron, 1990;Hildreth, 2004).…”

Section: Temporal Variations and Intrusion Ratesmentioning

confidence: 64%

“…Deep LP events like those associated with Mammoth Mountain have also been recorded adjacent to this chain (Pitt et al, 2002). Pockets of CO 2 gas and warm (36°C) CO 2 -rich water were encountered in an 18-km long tunnel excavated through this chain in the 1930s (Jacques, 1940), and weak steam vents have been described in a section of the ridge-top known as North Coulee (Larry Ford, USFS, pers.…”

Section: Introductionmentioning

confidence: 93%

See 1 more Smart Citation

Magmatic gas emissions at Holocene volcanic features near Mono Lake, California, and their relation to regional magmatism

Bergfeld

Evans

Howle

et al. 2015

Journal of Volcanology and Geothermal Research

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Section: Temporal Variations and Intrusion Ratesmentioning

confidence: 64%

Section: Introductionmentioning

confidence: 93%

Magmatic gas emissions at Holocene volcanic features near Mono Lake, California, and their relation to regional magmatism

Bergfeld

Evans

Howle

et al. 2015

Journal of Volcanology and Geothermal Research

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“…6b). Note, however, that the majority of low-frequency earthquakes that are likely related to the movement of magmatic fluid occurred at a depth of 15-20 km (Pitt et al 2002). With this sensitivity kernel, the 2013 velocity reduction registered only in the 0.5-to 0.9-Hz band most likely occurred at depth of ~1 km.…”

Section: Resultsmentioning

confidence: 94%

“…This hydrothermal system has been suggested to be driven by heat from cooling mafic magma reservoirs beneath the LVC (Clynne et al 2012). A number of long-period earthquakes (depth of 15-20 km) were detected in the LVC (Pitt et al 2002), which might represent movements of magma at depth. The extensively active Lassen hydrothermal system may pose potential hazards to the Lassen region including emissions of gases and hydrothermal explosions.…”

Section: Introductionmentioning

confidence: 98%

Response of hydrothermal system to stress transients at Lassen Volcanic Center, California, inferred from seismic interferometry with ambient noise

Taira

Brenguier

2016

Earth Planets Space

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Abstract:Time-lapse monitoring of seismic velocity at volcanic areas can provide unique insight into the property of hydrothermal and magmatic fluids and their temporal variability. We established a quasi real-time velocity monitoring system by using seismic interferometry with ambient noise to explore the temporal evolution of velocity in the Lassen Volcanic Center, Northern California. Our monitoring system finds temporal variability of seismic velocity in response to stress changes imparted by an earthquake and by seasonal environmental changes. Dynamic stress changes from a magnitude 5.7 local earthquake induced a 0.1 % velocity reduction at a depth of about 1 km. The seismic velocity susceptibility defined as ratio of seismic velocity change to dynamic stress change is estimated to be about 0.006 MPa −1 , which suggests the Lassen hydrothermal system is marked by high-pressurized hydrothermal fluid. By combining geodetic measurements, our observation shows that the long-term seismic velocity fluctuation closely tracks snowinduced vertical deformation without time delay, which is most consistent with an hydrological load model (either elastic or poroelastic response) in which surface loading drives hydrothermal fluid diffusion that leads to an increase of opening of cracks and subsequently reductions of seismic velocity. We infer that heated-hydrothermal fluid in a vapor-dominated zone at a depth of 2-4 km range is responsible for the long-term variation in seismic velocity

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“…LP earthquakes (sources with dominant periods of 0.2–2 s) beneath Mammoth Mountain were first identified in 1989 in conjunction with an 11 month long earthquake swarm [ Pitt and Hill , ; Hill , ; Pitt et al , ]. The LP seismicity typically occurs between depths of ∼10 and 25 km and often in clusters of events lasting for tens of minutes.…”

Section: A Restless Volcanomentioning

confidence: 99%

Tomographic image of a seismically active volcano: Mammoth Mountain, California

2016

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High‐resolution tomographic P wave, S wave, and VP/VS velocity structure models are derived for Mammoth Mountain, California, using phase data from the Northern California Seismic Network and a temporary deployment of broadband seismometers. An anomalous volume (5.1 × 109 to 5.9 × 1010m3) of low P and low S wave velocities is imaged beneath Mammoth Mountain, extending from near the surface to a depth of ∼2 km below sea level. We infer that the reduction in seismic wave velocities is due to the presence of CO2 distributed in oblate spheroid pores with mean aspect ratio α = 1.6 × 10−3 to 7.9 × 10−3 (crack‐like pores) and mean gas volume fraction ϕ = 8.1 × 10−4 to 3.4 × 10−3. The pore density parameter κ = 3ϕ/(4πα) = na3=0.11, where n is the number of pores per cubic meter and a is the mean pore equatorial radius. The total mass of CO2 is estimated to be 4.6 × 109 to 1.9 × 1011 kg. The local geological structure indicates that the CO2 contained in the pores is delivered to the surface through fractures controlled by faults and remnant foliation of the bedrock beneath Mammoth Mountain. The total volume of CO2 contained in the reservoir suggests that given an emission rate of 500 tons day−1, the reservoir could supply the emission of CO2 for ∼25–1040 years before depletion. Continued supply of CO2 from an underlying magmatic system would significantly prolong the existence of the reservoir.

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Midcrustal, Long-period Earthquakes beneath Northern California Volcanic Areas

Cited by 48 publications

References 26 publications

Magmatic gas emissions at Holocene volcanic features near Mono Lake, California, and their relation to regional magmatism

Magmatic gas emissions at Holocene volcanic features near Mono Lake, California, and their relation to regional magmatism

Response of hydrothermal system to stress transients at Lassen Volcanic Center, California, inferred from seismic interferometry with ambient noise

Tomographic image of a seismically active volcano: Mammoth Mountain, California

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