진안분지의 퇴적시기와 화산활동 및 백두산 형성 시, 마그마 챔버 위치의 변화에 대한 연구

이승환 전북대학교 일반대학원 2017 국내석사

Chapter 1. Time interval of sedimentation and volcanic activity in the Cretaceous Jinan Basin The Jinan Basin is one of the Cretaceous pull-apart Basins in South Korea located along the Yongdong-Gwangju fault system. Field works were conducted for 4 sites along the line crossing the Jinan Basin. Each site consists of sedimentary rocks with interlayered volcanic rocks and is named as J1, J2, J3 and J4 respectively from the northwest to southeast along the line. The J1, J2, J3 and J4 sedimentary outcrops locate in the Manducsan, Dalgil, Sansudong and Maisan formations. (LA-MC-ICPMS) age dating was carried out on the zircons from sedimentary and igneous rocks in those sites. The youngest detrital ages obtained from the bottom and top of sedimentary sequences near to J1 in the northwestern margin are 93.8Ma and 89.47 Ma respectively and that from the bottom of J3 in the center is 97.7 Ma. Basaltic andesite in the northwestern margin of the Jinan Basin gives age of 90.30Ma. Basalt in J3 gives an eruption age of 91.81Ma. The ages obtained from the rhyolitic sill and rhyolite in J3 in the center part of Jinan Basin, are 89.6 Ma, 88.87 Ma respectively. 84.56Ma was obtained from andesite intrusion in center part of the Jinan Basin. Andesite in the southwestern part of Jinan Basin gives 84.2Ma. The Jinan Basin began to form asymmetrically with the deepest part in the J3 locating in the southwestern part of the Basin from 97-93Ma. At the beginning stage of the Basin, conglomerate was mainly deposited in both margins while sandstone was mainly deposited in the center; the coarser cobble size in the J4 compared to J1 indicates that slope of the southeastern margin of the Basin was steeper than that of the northeastern margin. In the second stage, sandstone to shale or mud were deposited in the J2 and J3 and from conglomerate and less coarse conglomerate and sandstone in the J1 and J4 implying fining upward. In the third stage shale and sandstone deposited alternatively deposited in the J2 and J3 and conglomerate mainly deposited in J1 and J4. At the beginning of this stage basalt or basaltic andesite extruded at 90-92 Ma and later rhyolitc and andesitic magma intruded the Jinan Basin at 90-89 Ma and 85-84 Ma respectively. These data indicate that the deposition had started from 97-92 Ma and continued at least until 85-84 Ma implying that the sedimentary sequence of the Jinan Basin can be correlated to the Yucheon Group in the Gyeongsang Basin. Rhyolitic volcanic rocks in and around the Jinan Basin are plotted on the VAG (Volcanic Arc Granite) field and basaltic to intermediated volcanic rocks are plotted on the CAB (continental arc basalt) fields in the tectonic discrimination diagrams. From the 84.5 Ma and 84.2 andesite in the center and southeastern parts of the Jinan Basin, 7.9~8.5kbar and 2.1~3.7kbar are for the depth of magma chamber These data suggest that the igneous rocks in the Jinan Basin had formed from mantle or crustal rocks due to the Cretaceous subduction and moved up to the depth of middle to upper crust forming magma chamber. The fault around the Jinan Basin may be the path of magma from deep part to middle to upper crust. Chapter 2. The study on the change of magma chamber during forming of the Baekdu volcano. The Baekdu volcano consists of basaltic plateau, basaltic shield and trachytic stratocone. The formation process of the Baekdu volcano is divided into four stages. In the first stage, basaltic plateau formed by fissure eruption during 28~6.5 Ma. After that, in the second stage, basaltic shield formed by fissure and central eruption at 6.5~0.31 Ma. In the third stage, trachytic stratocone formed on the basaltic shield during 0.25~0.09 Ma. Trachytic stratocone consists of Xiaobaishan, Lower, Middle and Upper trachyte from bottom to top with rhyolite and comendite. In the latest stage, ignimbrite was erupted explosively. During the basaltic plateau stage, the Dagusan basalt erupted at 11.98±0.2 7Ma and its magma chamber was expected to locate at the depth of ca. 16.8~17.0 kbar (ca. 55~56km). During the basaltic shield stage, the Toudao and Baishan basalts erupted at 6.50±0.86 Ma, 2.67±0.32 Ma and 1.09±0.03 Ma; the depth of magma chambers for each eruption were 4.1~5.5 kbar (ca. 15~18km), 6.2~7.8 kbar (ca. 20~26km) and 14.0~14.4 kbar (ca. 46~47km) respectively. The depth of magma chamber for the Xiaobaishan trachtye which erupted at 0.25±0.06 Ma forming the lowest part of the Baekdu strato cone, is estimated as 8.7kbar (ca. 28.7km). 5.6~6.1kbar (ca. 18~20km) and 11.5~13.6kbar (ca. 38~45km) depths of magma chambers are estimated for the Middle trachyte with eruption age of 0.07±0.01Ma and the comendite which erupted at 0.21±0.06Ma together with trachytic volcanic rocks. This study together with previous studies on the magma chambers under Bakdu volcano suggests that under the Baekdu volcano, various magma chambers had formed at depth of 14~18km, 18~20km, 20~25km, 28km, 38~44km, 46~47km and 55~56km respectively. During the basalt plateau stage, erupted magma may have come from the deepest magma chamber locating in the lithospheric mantle, whereas, during the shield and cone stages, erupted magma came from the three magma chambers which located in the continental crust. Basaltic to comenditic volcanic rocks in and around the Baekdu volcano are plotted on the WPG (Within Plate Granite) in the tectonic discrimination diagrams implying that the Backdu volcano formed in the within plate tectonic setting.

Time Series InSAR Techniques for Mapping Surface Deformation on the Augustine and Seguam volcanoes in the Aleutian Islands, Alaska

이창욱 연세대학교 대학원 2009 국내박사

There are approximately 130 volcanoes in Alaska extending over the 2,500-kilometer-long Aleutian Arc, and 50 volcanoes among them were confirmed having experienced around 230 eruptions since 1760. It implies that they had almost one eruption per year on average. Monitoring and studying hazardous volcanoes in Alaska are essential to record and to predict eruptive activity in order to mitigate volcanic hazards to lives and properties. This study focuses on the measurement of surface deformation of two active volcanoes in the Aleutian arc, Alaska, using a small baseline subset (SBAS) interferometic synthetic aperture radar (InSAR) technique and the retrieval of magma source parameters using Mogi model. First, a SBAS InSAR technique has been developed to study time-series deformation through a multiple-interferogram approach that reduces the atmospheric artifacts, DEM errors and other artifacts presented in the conventional InSAR analysis. Second, the improved SBAS InSAR technique has been applied to the Augustine Volcano to study ground surface deformation during 1992-2005 using synthetic aperture radar (SAR) data from three descending and three ascending satellite tracks acquired by European Remote Sensing Satellite (ERS) 1 and 2, and the Environment Satellite (ENVISAT). Interferograms during 1992 and 2005 show a subsidence of about 1-3 cm/year, caused by the contraction of pyroclastic flow deposits from the 1986 eruption. The deformations resulted from the two independent satellite tracks agree with each other, suggesting 2-8 cm overall uplift. GPS data acquired between September 2004 and October 2005 confirmed the SBAS InSAR measurements. A preliminary model using multiple sources of a contracting source at 2-4 km depth and an inflating source at 7-12 km fits the observed deformation reasonably well. Third, a time-series of ERS-1/2 radar interferograms have been generated and the SBAS InSAR processing has been also applied to study the deformation of the Seguam Volcano from 1992 to 2007. Location and volume changes of magma sources were modeled using the Mogi model. Subsidence, observed at each of three calderas on the Seguam Island, is more closely correlated with individual activity of shallow sources located directly below each caldera. These calderas show the subsidence rates of about 0.5-1.5 cm/year due to the process from the shallow source of 1.5-2 km depth by hydrothermal fluids, or thermoelastic contraction of lava flows through the volume changes from about -0.6x10-4 to -0.1x10-3 km3/year. However, the eastern caldera has experienced alternating subsidence and uplift processes in association with a deep source as well as a shallow sources. From time to time, the eastern caldera had the uplift patterns which corresponded to a volume change of about 0.1-0.2 x10-2 km3/year that were associated with deep source of 5 km in depth and might be resulted from magma intrusion. The observation period was divided into four sub-stages according to the deformation pattern. While the subsidence around the eastern caldera had been caused by deflation of shallow source, the uplift might have been influenced by a deep source. These results of precise surface deformation mapping with an improved SBAS InSAR technique provide better understandings of the dynamic magma plumbing systems in the Augustine and the Seguam volcanoes.

Time series InSAR rechniques for mapping surface deformation on the augustine and seguam volcanoes in the Aleutian Islands, Alaska

이창욱 Graduate School, Yonsei University 2009 국내박사

(The) volcanism in northeast Japan : a numerical model study

유수환 Graduate School, Yonsei University 2022 국내석사

In Northeast Japan, the Quaternary volcano clusters and the no–volcano zones between them imply extensive and scarce melting of the mantle wedge, respectively, but no quantitative study to explain the melt distribution and transport with realistic rheology and subduction condition has been conducted yet. Here, we conducted a series of two–dimensional numerical models by considering along–arc temperature variations in the mantle wedge expressed as high– (hot fingers) and low–temperature anomalies (deterred corner flow) with the slab dehydration, mantle (de)hydration, transport of free water and water bounded in mineral, flux melting and melt transport in the mantle wedge with realistic mantle rheology. Model calculations show that the high mantle temperature in the hot finger and the near–complete slab dehydration generate the extensive melting from the sub–arc to –backarc mantle, consistent with the melt distribution constrained by seismic tomography and the geochemically estimated melt production rate. Large melt fraction in the sub–arc mantle results in the enhanced melt buoyancy, indicating the high melt separation velocity. During the melt upward migration, the melt solidification occurs where the mantle solidus is lower than the melt temperature. Small melt fraction caused by the melt solidification results in the melt behavior dominated by the corner. Thus, the melt generated from the sub–arc to –backarc mantle is dragged by the corner flow and focused to the sub-arc mantle beneath the volcano clusters, consistent with the geographically focused volcanoes. In the meantime, the low–temperature anomaly and partial slab dehydration beneath the no–volcano zones generate the negligible melting and the partially dehydrated subducting slab transports the remaining water into the mantle transition zone through deep slab dehydration, which may be responsible for the intraplate volcanoes in Northeast Asia. 북동 일본에는 제4기에 형성된 화산 군집이 존재한다. 화산 군집 아래에는 방대한 맨틀의 유체 유입 용융이 발생하며 화산 군집 사이 맨틀에서의 부분 용융은 거의 일어나지 않는 것으로 알려졌다. 그러나 북동 일본 아래에서의 맨틀 부분 용융에 대한 정량적인 연구가 수행되지 않았다는 점에 주목하여 맨틀의 부분 용융과 마그마의 거동을 정량적으로 연구하였다. 이를 위하여 화산 군집 아래의 높은 온도의 맨틀과 그 사이의 낮은 온도의 맨틀을 고려한 2차원 컴퓨터 수치 모델링을 수행하였다. 섭입해양판의 탈수, 맨틀 쐐기의 흡∙탈수, 광물 속의 물과 자유수의 유동, 맨틀 쐐기에서의 유체 유입 용융 그리고 마그마의 유동을 정량적으로 계산하였다. 북동 일본의 화산 군집 아래 높은 온도 이상에 의해 발생한 섭입해양판의 완전한 탈수는 호 아래 맨틀부터 배호 아래 맨틀까지의 방대한 유체 유입 용융을 발생시키며 이러한 유체 유입 용융은 지화학적으로 유추된 마그마 발생량과 일치한다. 호 아래 맨틀의 방대한 마그마는 강한 부력을 일으켜 빠른 마그마 분리가 발생, 상승한다. 온도 감소에 따른 맨틀 점성도 증가와 마그마 고화에 의하여 낮은 깊이의 맨틀에서 마그마는 맨틀 쐐기의 구석 유동에 의해 거동이 지배된다. 그 결과 마그마는 호화산 군집 아래로 수렴하며, 마그마의 분포는 지진파 단층도로 파악된 분포와 잘 호응한다. 화산이 없는 지역 아래에서는 낮은 맨틀 온도와 부분적인 섭입해양판의 탈수로 무시할 정도의 부분 용융이 발생한다. 그 결과 북동 아시아의 판 내부 화산과 연관성이 있는 맨틀 전이대까지의 물의 전달은 부분적으로 탈수된 섭입해양판이 공급할 것으로 판단된다.

Imaging Trans-Crustal Magma Systems in the Central Andes With InSar, Gravity, and Rock Physics Analysis

MacQueen, Patricia Grace Cornell University ProQuest Dissertations & Theses 2023 해외박사(DDOD)

The most enduring mysteries in volcanology cannot be tackled by one method alone. Different methods give complementary insights on the same structures and processes. In this dissertation I use InSAR (Interferometric Synthetic Aperture Radar), gravimetry, and rock physics in concert with other data to investigate volcano-tectonic interactions and volcanic structure and life cycles. A major theme of my work is integrating geodetic methods with complementary data to synthesize a self-consistent picture of the volcanic system, including using rock physics to quantitatively link geology to geophysical parameters. The Central Volcanic Zone of the Andes contains informative end-members for studying the extremes of volcanic processes. Sabancaya volcano in Peru experienced some of the strongest earthquakes ever recorded near a volcano without coincident eruption, and Uturuncu volcano in Bolivia exhibits signs of unrest despite having no eruptions in over 250,000 years. At Sabancaya volcano I calculate a 4 year long InSAR time series, combining this with other InSAR time series and seismic, thermal, and geological data to determine that magmatic intrusion in fluid-saturated crust triggered the unusually strong seismicity at this volcano. I then turn to Uturuncu volcano, where I generate an updated density contrast model of the volcano's shallow subsurface. Combining this model with a published resistivity model, I argue that Uturuncu's unrest may be partially due to ongoing ore body formation. I build on this work with a quantitative, rock-physics based joint analysis of density contrast, resistivity, and seismic tomography models of Uturuncu's shallow subsurface. My self-consistent, petrologically informed analysis shows that shallow (<10 km) geophysical anomalies at Uturuncu are quantitatively consistent with a hydrothermal system with up to 8 vol.% of 3 wt.% NaCl brines and inconsistent with large zones of dacite melt or mush. At both Sabancaya and Uturuncu, my work demonstrates the key role of aqueous fluids in driving volcanic unrest and breaks new ground in synthesizing multiparameter data in the quest to understand the structure and workings of volcanic systems.

Nonlinear Propagation and Topographic Diffraction of Volcano Infrasound

Maher, Sean University of California, Santa Barbara ProQuest D 2022 해외박사(DDOD)

Volcanic eruptions emit sound waves that are typically dominant at infrasonic frequencies (~0.01–20 Hz) and that have been used to estimate eruption source parameters valuable for hazard mitigation. However, the accuracy of these estimates depends on the ability to recover the pressure-time history of the acoustic source, which may be distorted during propagation even at local recording distances (<15 km). We aim to quantify potential distortions caused by diffraction over topography and wave steepening during nonlinear propagation.To investigate the effects of topographic diffraction, we evaluate the ability of a thin screen approximation to predict amplitude losses over topography at Sakurajima Volcano, Japan. Using synthetic data from numerical modeling, we show that amplitude losses from diffraction over volcano topography are systematically less than predicted for a thin screen. We propose that attenuation by diffraction may be counteracted by acoustic focusing (constructive interference between reflections along concave slopes). We conclude that thin screens are inappropriate proxies for volcano topography, and maintain that numerical simulations are required to account for wavefield interactions with topography.To investigate the role of near-source nonlinear propagation in volcano infrasound, we apply a previously developed, quadspectral density-based nonlinearity indicator to observed and synthetic signals corresponding to explosive eruptions at Sakurajima Volcano, Japan and Yasur Volcano, Vanuatu. We hypothesize that significant nonlinearity will be expressed as energy transfer from low to high frequencies as the acoustic waves steepen towards shock waves. At Sakurajima Volcano we find evidence for spectral energy transfer in the synthetic data but inconclusive results from the observed signals, suggesting that nonlinearity signatures may be present but obscured by complicating factors (e.g., topography, wind, waveform undersampling). At Yasur Volcano we find evidence for nonlinearity in both synthetics and observations, suggesting that nonlinearity is better observed at short source-receiver distances and with higher sampling rates. At both volcanoes we estimate that cumulative spectral changes by nonlinear propagation are small (<1% of source levels). We conclude that, for signal amplitudes associated with low-level explosions common in field campaigns, nonlinear propagation does not introduce significant errors to acoustically-based source parameter estimates when compared to a linear assumption.

Atmospheric correction technique in SAR interferometry for monitoring volcanic activities

정정교 서울대학교 대학원 2013 국내석사

Ground deformation in volcano is a consequence of changes in magma chamber’s volume. Magma storage, migration and volume change is closely associated phenomena with the ground deformation. Therefore, measuring ground deformation provides important information to understand the volcanic activities. For some specific volcanoes, such as Shinmoedake volcano, ground deformation of even a few centimeters can occur before eruption. Thus, measuring ground deformation needs to be fairly accurate. SAR interferometry is a potential technique to measure the ground deformation accurately. One of the limitations in SAR interferometry, however, is atmospheric phase delay effects, which are induced when microwave propagates into the atmosphere. In this aspect, various methods for mitigating atmospheric phase delay effects have been developed. This study aims to mitigate the atmospheric phase delay especially in volcano because the stratified and turbulent atmospheric phase delay effects could severely contaminate the deformation patterns. First method used in this study is the atmospheric correction technique using MODIS data. Multispectral observation can measure the integrated water vapor in the atmosphere by analyzing ratios of water vapor absorbing channel and atmospheric window channel. It can be directly used for calculating the tropospheric phase delay effect caused by water vapor. Recent researches using multispectral datasets are restricted to approach using ENVISAT. Therefore, new approach is necessary in application using ALOS PALSAR. This study evaluates the applicability and possibility. In adequate temporal difference and cloud coverage, available datasets of MODIS successfully converted to the atmospheric phase delay corresponding to SAR acquisition time. However, there are some limitations in application into all dataset because of the cloud cover and temporal difference between the SAR acquisition time and MODIS acquisition time. In spite of limitations, the use of MODIS data in atmospheric correction yield better results and minimize misinterpreted errors. The WRF model complements the limitations of MODIS data. In this respect, an application of the WRF model in atmospheric correction of differential interferogram was carried out in the second methods. The estimated APS from the WRF model can explain the stratified APS involved in differential interferograms. However, the accuracy of model prediction should be evaluated. The direct use of the WRF model predictions for atmospheric correction yield errors for mitigating the turbulent APS and the small-scaled APS. Final approach is a time-series analysis. In model experiments, several properties of atmospheric phase screen (APS) are found out. The first is that APS could remain in a time-series analysis and mainly comes from the stratified APS. The second is that it is possible to estimate and minimize the stratified APS by using sufficient WRF models. In the case of the turbulent APS, time-weighting low pass filtering is capable to reduce it. Therefore, the main idea of the atmosphere corrected time-series analysis adopt the stratified APS and turbulent APS correction method using WRF model and time-weighting methods. In comparison with observational dataset such as GPS and MODIS dataset, the estimated ground deformation and APS from the atmosphere corrected method have low rms errors, and high correlation. Therefore, this method can be believed as an accurate approach for measuring the ground deformation in volcanic region.

Acoustic and Seismic Signature of Sustained Volcanic Eruptions

Gestrich, Julia E University of Alaska Fairbanks ProQuest Dissertati 2022 해외박사(DDOD)

Volcanic eruptions of any size can pose a significant risk to the life and livelihood of humans, as well as to infrastructure and the economy. Understanding the dynamics of an eruption is crucial to providing timely and accurate assessments of the eruption and associated hazard. Ideally the monitoring of volcanic unrest and eruption dynamics is done remotely to minimize exposure to volcanologists and maximize the spatial monitoring coverage of instruments. Another important factor is to have real-time data to facilitate rapid analysis and interpretation. Seismic and acoustic (infrasound) waves have proven useful in terms of remote real-time volcano monitoring. However, accurate interpretation of these signals is a challenge due to the complexity of each volcano and each eruption. In this dissertation I present three projects that aim to improve the interpretation of seismic and acoustic signals, specifically their spectral properties, generated by multiphase flow during an eruption. In Chapter 2 we derive a seismic tremor model for a source underground but above the fragmentation level where the gas and particles rush through the volcanic conduit. This physical model assumes ash particles and gas turbulence impact the conduit wall and exert a force that generates seismic waves and is recorded as eruption tremor. We show that it is possible to model the seismic spectral amplitude and shape of a large sustained volcanic eruption, the eruption of Pavlof Volcano in 2016, with particle impacts and turbulence as seismic sources. Our modeling provides a framework to 1) narrow down the parameters associated with eruption dynamics and source processes, and 2) highlight that seismic amplitude and mass eruption rate are not necessarily correlated. Both findings are crucial for the successful interpretation of seismic data during a sustained eruption. In Chapter 3 we move further up above the vent to investigate the acoustic expression of sustained eruptions. The rapid discharge of the multiphase flow through the relatively small vent has been successfully compared to jetting in the past. We develop an algorithm to automatically fit laboratory-derived jet noise spectral shapes (similarity spectra) to the spectrum of three volcanic eruptions: Mount St Helens 2005, Tungurahua 2006 and Kilauea 2018. Our quantitative analysis of the misfit between the jet noise spectra and volcanic eruption shows that: 1) the jet noise spectra show a very good fit during the eruption, so we can assume it produces a volcanic form of jet noise, 2) we can distinguish between non-eruptive noise and eruption by the higher misfit of the former and the lower misfit of the latter, and 3) changes in spectral shape correspond to changes in eruption dynamics, which are highlighted by changes in the misfit in time and frequency space. To further look into how changes in spectral properties correspond to changes in eruption dynamics, Chapter 4 focuses in detail on the eruption of fissure 8 on Kilauea volcano in 2018. With the knowledge that the eruption produced jet noise (Chapter 3) we apply jet noise scaling laws and develop a model that relates the changes in infrasound amplitude and peak frequency to changes in jet velocity and diameter. Our analysis shows that in mid-June the infrasound amplitude peaks and the peak frequency decreases. Our jet noise scaling model explains this change through a decrease in jet velocity and increase in jet diameter. This interpretation fits video observations that show a decrease in lava fountain height and a widening of the fountain base around the same time. Our work demonstrates the potential to estimate lava fountain dimensions from infrasound recordings that could be useful for real-time, remote monitoring.

Structural Seismology of the Arabian Plate and Volcano Seismology Near the Red Sea Rift Margin

Blanchette, Alexander Robert ProQuest Dissertations & Theses Stanford Universit 2022 해외박사(DDOD)

Brittle-failure earthquakes require that rocks deform via a brittle mechanism, instead of a viscous deformation mechanism. This requires that the material is cool, or that strain rates are high, to support such deformation. Exploiting the observation of brittle-failure earthquakes in the mantle lithosphere I was able to perform earthquake geothermometry. Combining this with surface measurements of heat flow, and the thickness of the crust and lithosphere, I determined that Harrat Lunayyir, Saudi Arabia, is out of thermal equilibrium due to having experienced a second stage of lithospheric thinning at 15--12 Ma. This second stage thinned the lithosphere to its present day 60-km thickness, following initial Red Sea extension which occurred ~27 Ma.The thickness of the crust beneath the Kingdom of Saudi Arabia was poorly mapped, with few historic data. I applied a conventional H-k stacking algorithm and included careful attention to stacking weights, sedimentary corrections for stations located on the Arabian Platform, and additional processing for noisy stations. Average crustal thickness (that is, depth to the Mohorovicic discontinuity [Moho] below the surface) beneath the Red Sea coastal plain (the rift margin) is 29 km, beneath the volcanic fields (locally known as harrats) is 35 km, beneath the Arabian Shield (excluding harrats) is 37 km, and beneath the Arabian Platform is 38 km. Crustal thinning appears not to extend east of the rift escarpment, suggesting uniform extension during Red Sea rifting that is no broader at depth than at the surface. I found no statistically significant difference between the total crustal thicknesses of the Arabian Shield and Platform. However, the average subsedimentary crustal thickness (that is, the crystalline crust) for stations on the Arabian Platform is 34 km, 3 km thinner than the crust of the Arabian Shield. There are no statistically significant differences between VP/VS ratios of the different geologic regions of Saudi Arabia. Similar VP/VS ratios, coupled with similar crustal thicknesses for harrats and the Arabian Shield, indicate that Cenozoic magmatism has contributed negligibly to crustal growth.Volcanic earthquakes, in particular those due to the migration of magmatic fluids, elicit much curiosity around the world (e.g., Iceland, Hawaii, Mount St. Helens, etc.) in the hopes of illuminating the internal dynamics of the magmatic system and improving eruption monitoring protocols. It is only recently that volcanic earthquakes in the lower-crust and lithospheric-mantle are being recognized. Harrat Lunayyir exhibits discrete episodic pulses of seismicity in the mantle lithosphere, over a timespan of > 20 years. The seismicity there includes a few earthquakes within the nominally aseismic lower-crust, and ample seismicity during the decade post-dike intrusion. It also exhibited numerous discrete pulses of seismicity that migrated from near the base of the crust to near the surface, for about a decade before the 2009 dike intrusion. This seismicity is driven by asthenosphere derived magmatic fluids (melt, or possibly) and the continued seismicity suggests there has been no appreciable depletion of the asthenospheric magma source.

Geodetic Exploration of the Kinematics and Fault Slip Rates of the Southeastern and Western Caribbean Plate Boundaries and the Caldera Dynamics of the Sierra Negra Volcano

Higgins, Machel The Pennsylvania State University ProQuest Dissert 2021 해외박사(DDOD)