Penny Wieser
@pennywieser.bsky.social
Assistant Prof studying Volcanoes. ♥️Microanalysis, Python 🐍, Open Science. Laser Radial sailor ⛵, Bike advocate 🚲. Chronically Ill (GI). She/her
Two bike accidents in 2 years, both cycling home from office hours. Can't decide if we should ban cars or ban office hours. Driver left hooked me across a two way cycle lane without even looking in his mirrors. Also second crash where helmet saved my head. #WearAHelmet #Lookinyourgoddamnmirrors
October 7, 2025 at 1:41 AM
Two bike accidents in 2 years, both cycling home from office hours. Can't decide if we should ban cars or ban office hours. Driver left hooked me across a two way cycle lane without even looking in his mirrors. Also second crash where helmet saved my head. #WearAHelmet #Lookinyourgoddamnmirrors
We suggest that at both volcanoes the mush piles are as large as they can be, adding more olivine causes material to flow into the rift zones, and they are unable to get any larger without this happening. Overall, we think the plumbing system is dominated by one main reservoir at 3-5 km depth.
September 30, 2025 at 3:23 PM
We suggest that at both volcanoes the mush piles are as large as they can be, adding more olivine causes material to flow into the rift zones, and they are unable to get any larger without this happening. Overall, we think the plumbing system is dominated by one main reservoir at 3-5 km depth.
Interesting, the degree of deformation (quantified by the grain orientation spread or linear intercept distances) and the proportion of diferent fabrics was very similar to Kīlauea. This is surprising - Mauna Loa is bigger, has been active much longer, so should have a more accumulated olivine.
September 30, 2025 at 3:22 PM
Interesting, the degree of deformation (quantified by the grain orientation spread or linear intercept distances) and the proportion of diferent fabrics was very similar to Kīlauea. This is surprising - Mauna Loa is bigger, has been active much longer, so should have a more accumulated olivine.
We also looked at olivine deformation systematics. The picrites in particular show beautiful subgrains forming. By looking at the strike of subgrain boundaries, their weighted burgers vectors, and misorientation axes, we were able to identify the olivine slip systems responsible
![Signatures of deformation in Mauna Loa olivines. The leftmost column shows an EBSD map with each pixel colored using an inverse-pole figure (IPF) key (inset) where the color shows both the magnitude and direction of the deviation from the mean orientation of the grain (defined as white), with black colors showing deviation in orientation from the mean by more than 3°. Deformation intensity visibly decreases with decreasing GOS from a-c, shown by colors getting less intense, and showing a narrower range of hues. The central column shows the WBVD, with [100] directions as blue, [010] as green, and [001] as red. Note, this is different from the WBVD color key used in Wieser et al. (2020), but this cannot be changed in the software Aztec Crystal. The rightmost column shows the misorientation axes across the black subgrain boundaries marked on the IPF map. The colorbar shows the intensity of the coloring, e.g. a value of 16 means the orientations are 16X more concentrated in that region than elsewhere.](https://cdn.bsky.app/img/feed_thumbnail/plain/did:plc:vvbdpfdpbmmrizpjylro2cdx/bafkreib767hz5byuaedq7ng4cjioumzod3cnv7ncejwoonxugkagwbbm7i@jpeg)
September 30, 2025 at 3:20 PM
We also looked at olivine deformation systematics. The picrites in particular show beautiful subgrains forming. By looking at the strike of subgrain boundaries, their weighted burgers vectors, and misorientation axes, we were able to identify the olivine slip systems responsible
The more observant will notice there is a LOT of scatter in SO2 mol%, and at a given pressure, some have SO2 and some dont. We think this is because of the sluggish diffusion of SO2, and rapid FI sealing off. Sarah Shi did a great job of modelling this. Takes minutes to get SO2 into the FI.
September 30, 2025 at 3:18 PM
The more observant will notice there is a LOT of scatter in SO2 mol%, and at a given pressure, some have SO2 and some dont. We think this is because of the sluggish diffusion of SO2, and rapid FI sealing off. Sarah Shi did a great job of modelling this. Takes minutes to get SO2 into the FI.
The higher mol% SO2 at a given pressure vs. Kīlauea is explained by SulfurX, and XANES measurements by Saper showing higher S6+ proportions. The early degassing accounts for the otherwise confusing precursory SO2 emissions reported by Ben Esse. I was so excited I saw this! doi.org/10.1007/s004...
September 30, 2025 at 3:16 PM
The higher mol% SO2 at a given pressure vs. Kīlauea is explained by SulfurX, and XANES measurements by Saper showing higher S6+ proportions. The early degassing accounts for the otherwise confusing precursory SO2 emissions reported by Ben Esse. I was so excited I saw this! doi.org/10.1007/s004...
The most exciting result is the fact that we found lots of SO2 in our Raman spectra - it is typically stated that SO2 only degasses in the upper few 100m in Hawaii (cyan DCompress model). Our data suggests it starts degassing at a few km. This is backed up by newer models (e.g. SulfurX)....3/N
September 30, 2025 at 3:13 PM
The most exciting result is the fact that we found lots of SO2 in our Raman spectra - it is typically stated that SO2 only degasses in the upper few 100m in Hawaii (cyan DCompress model). Our data suggests it starts degassing at a few km. This is backed up by newer models (e.g. SulfurX)....3/N
Our fluid inclusion storage depths are remarkably consistent across eruptions spanning 10 kyrs, and align extremely well with geophysical estimates of magma storage. They are a bit deeper than Kīlauea (centered at 3 km vs. 1-2 km). Seems shield stage magma storage is stable once established. 2/N
September 30, 2025 at 3:10 PM
Our fluid inclusion storage depths are remarkably consistent across eruptions spanning 10 kyrs, and align extremely well with geophysical estimates of magma storage. They are a bit deeper than Kīlauea (centered at 3 km vs. 1-2 km). Seems shield stage magma storage is stable once established. 2/N
Second open access Mauna Loa paper available! Here we investigate storage depths and degassing systematics using fluid inclusions, and olivine deformation using EBSD in lavas and tephras from 7 eruptions (1852-2022). TLDR: SO2 degasses earlier than expected doi.org/10.1007/s004...
September 30, 2025 at 3:09 PM
Second open access Mauna Loa paper available! Here we investigate storage depths and degassing systematics using fluid inclusions, and olivine deformation using EBSD in lavas and tephras from 7 eruptions (1852-2022). TLDR: SO2 degasses earlier than expected doi.org/10.1007/s004...
Way too hot in Berkeley this evening (33C), so headed down to spend a few hours in the amazing microclimate at the marina (21C). Bay area temperature gradients over 3 miles are something else. Caught an awesome sunset too.
September 24, 2025 at 3:02 AM
Way too hot in Berkeley this evening (33C), so headed down to spend a few hours in the amazing microclimate at the marina (21C). Bay area temperature gradients over 3 miles are something else. Caught an awesome sunset too.
We suggest that they form through melt-mush reaction in a olivine-dominated cumulate. Thanks to my great student Berenise, help from bluesky coauthors @alexbearden.bsky.social and @cljdevitre.bsky.social + many more!
September 23, 2025 at 3:17 PM
We suggest that they form through melt-mush reaction in a olivine-dominated cumulate. Thanks to my great student Berenise, help from bluesky coauthors @alexbearden.bsky.social and @cljdevitre.bsky.social + many more!
The only other interesting thing to say - these textures were originally intepreted as co-crystallization of Opx and Ol. But it becomes apparent with thin section scans the Opx are large oikocrysts, enclosing rounded olivines.
September 23, 2025 at 3:14 PM
The only other interesting thing to say - these textures were originally intepreted as co-crystallization of Opx and Ol. But it becomes apparent with thin section scans the Opx are large oikocrysts, enclosing rounded olivines.
Opx stability at low pressures at Mauna Loa is stabilized by the higher SiO2 content of these melts than
Kīlauea. Depending on the exact FC path, primary melts could have even higher SiO2, helping even more, pushing Opx stability to lower pressures.
Kīlauea. Depending on the exact FC path, primary melts could have even higher SiO2, helping even more, pushing Opx stability to lower pressures.
September 23, 2025 at 3:13 PM
Opx stability at low pressures at Mauna Loa is stabilized by the higher SiO2 content of these melts than
Kīlauea. Depending on the exact FC path, primary melts could have even higher SiO2, helping even more, pushing Opx stability to lower pressures.
Kīlauea. Depending on the exact FC path, primary melts could have even higher SiO2, helping even more, pushing Opx stability to lower pressures.
Another way we can test this - Take Opx bearing experiments and ask each model 'do you stabilize Opx'. The answer should be yes. Sadly, at <5 kbar, the models dont do a great job of Opx stability (a). Reflecting a lack of experimental constraints at the P-T conditions of interest (c-d).
September 23, 2025 at 3:10 PM
Another way we can test this - Take Opx bearing experiments and ask each model 'do you stabilize Opx'. The answer should be yes. Sadly, at <5 kbar, the models dont do a great job of Opx stability (a). Reflecting a lack of experimental constraints at the P-T conditions of interest (c-d).
Instead we need to look at the performance of the original pMELTS model used to show high pressures are needed for Opx. We model a variety of possible crystallization paths, and show pMELTS predicts far higher pressures of Opx stability than other models.
September 23, 2025 at 3:08 PM
Instead we need to look at the performance of the original pMELTS model used to show high pressures are needed for Opx. We model a variety of possible crystallization paths, and show pMELTS predicts far higher pressures of Opx stability than other models.
Berenise Rangel investigated the exact xenoliths analysed by Gaffney for her honours project (48g, 79a, 48i, 66d) using fluid inclusion barometry. I was actually pretty convinced she would find high pressures, but she didnt...In fact, her depths were very similar to my pressures obtained from tephra
September 23, 2025 at 3:05 PM
Berenise Rangel investigated the exact xenoliths analysed by Gaffney for her honours project (48g, 79a, 48i, 66d) using fluid inclusion barometry. I was actually pretty convinced she would find high pressures, but she didnt...In fact, her depths were very similar to my pressures obtained from tephra
Excited to share my new open-access paper looking at magma storage depths for these beautiful xenoliths from Mauna Loa Volcano. doi.org/10.1007/s004... 🧵below, TLDR - previous suggestions of ~20 km deep Opx crystallization are inconstant with fluid inclusion depths and thermodynamic modelling.
September 23, 2025 at 2:59 PM
Excited to share my new open-access paper looking at magma storage depths for these beautiful xenoliths from Mauna Loa Volcano. doi.org/10.1007/s004... 🧵below, TLDR - previous suggestions of ~20 km deep Opx crystallization are inconstant with fluid inclusion depths and thermodynamic modelling.
Already getting emails from my class!!!
September 22, 2025 at 10:19 AM
Already getting emails from my class!!!
First cold day of the semester, and the realization that spending a summer learning to wing foil means I have developed an anomalously muscley elbow joint/lower forearm and I now can't bend my arms in all my teaching blazers... 💪
September 4, 2025 at 5:41 PM
First cold day of the semester, and the realization that spending a summer learning to wing foil means I have developed an anomalously muscley elbow joint/lower forearm and I now can't bend my arms in all my teaching blazers... 💪
Undergraduate Isabelle Susman spreading the word about magma storage in American Samoa at today's MPS undergrad research fair. Isabelle is looking for PhDs and will be at GSA where you can all learn more! #ProudAdvisor
August 30, 2025 at 3:25 AM
Undergraduate Isabelle Susman spreading the word about magma storage in American Samoa at today's MPS undergrad research fair. Isabelle is looking for PhDs and will be at GSA where you can all learn more! #ProudAdvisor
Now my paper is submitted I have finally had to stop denying I need to teach 150 students in 2 weeks, and have managed to exceed the activation energy to start my course canvas page.
August 15, 2025 at 3:32 PM
Now my paper is submitted I have finally had to stop denying I need to teach 150 students in 2 weeks, and have managed to exceed the activation energy to start my course canvas page.
Flying around the bay today (with more crashes than you would want on a commerical flying object)! hydrofoils are truly the most amazing things. Physics is so cool that a 2000 cm2 piece of carbon fiber can lift a soaking wet me and a board into the air.
August 10, 2025 at 2:30 AM
Flying around the bay today (with more crashes than you would want on a commerical flying object)! hydrofoils are truly the most amazing things. Physics is so cool that a 2000 cm2 piece of carbon fiber can lift a soaking wet me and a board into the air.
VIBE lab group paddleboard/kayak outing to say goodbye to the wonderful @cljdevitre.bsky.social, the very first member of my lab group, who is starting as an Assistant Professor at UOttowa in Sept after nearly 3 years of fab fluid inclusion postdoc work🎉.
August 3, 2025 at 1:40 AM
VIBE lab group paddleboard/kayak outing to say goodbye to the wonderful @cljdevitre.bsky.social, the very first member of my lab group, who is starting as an Assistant Professor at UOttowa in Sept after nearly 3 years of fab fluid inclusion postdoc work🎉.
Spending the day tidying up all my code for a paper so the jupyter notebook for each figure and all its data it calls is in a tidy supplement. Great for FAIR principles, but also great for my sanity when doing revisions, and future Penny who is pretty sure she has already written code for that.
July 23, 2025 at 9:20 PM
Spending the day tidying up all my code for a paper so the jupyter notebook for each figure and all its data it calls is in a tidy supplement. Great for FAIR principles, but also great for my sanity when doing revisions, and future Penny who is pretty sure she has already written code for that.
Celebrating resubmitting a paper this morning! The bay area really is the most amazing natural playground - all you need is 3mm of neoprene and the world is your oyster. Finally making some progress with some sustained foil flights, and some accompanying large crashes!
July 17, 2025 at 11:53 PM
Celebrating resubmitting a paper this morning! The bay area really is the most amazing natural playground - all you need is 3mm of neoprene and the world is your oyster. Finally making some progress with some sustained foil flights, and some accompanying large crashes!