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Millions rely on dwindling Colorado River—but are kept 'in the dark' about fixes, critics say

Phys.org: Earth science - Mon, 10/06/2025 - 12:00

The Colorado River, which provides water across the Southwest, has lost about 20% of its flow in the last quarter-century, and its depleted reservoirs continue to decline. But negotiations aimed at addressing the water shortage are at an impasse, and leaders of environmental groups say the secrecy surrounding the talks is depriving the public of an opportunity to weigh in.

The real reasons Endurance sank—study finds Shackleton knew of ship's shortcomings

Phys.org: Earth science - Mon, 10/06/2025 - 10:00

Sir Ernest Shackleton's ship, Endurance, was crushed by Antarctic sea ice and sank in November 1915. Emblematic of the heroic age of Antarctic exploration, it is widely considered the strongest polar ship of its time, albeit with a fatal flaw—a weakness in the rudder that caused the ship to sink.

How marine heat waves reshape ocean food webs and slow deep sea carbon transport

Phys.org: Earth science - Mon, 10/06/2025 - 09:00

New research shows that marine heat waves can reshape ocean food webs, which in turn can slow the transport of carbon to the deep sea and hamper the ocean's ability to buffer against climate change.

A late monsoon sting in the tale in the Himalayas

EOS - Mon, 10/06/2025 - 07:25

Very heavy rainfall across Nepal, NE. India and Bhutan has triggered landslides that have killed at least 60 people.

Over the last few days, parts of the Himalayas have been hit by very high levels of rainfall, causing large numbers of damaging landslides. The picture is not yet fully clear, but Nepal and Bhutan, and Darjeeling in India, have been particularly badly hit.

Over on the wonderful Save the Hills blog, Praful Rao has documented the rainfall at in Darjeeling – for example, on 4 October 2025 Kurseong recorded 393 mm of rainfall, whilst in Kalimpong a peak intensity of about 150 mm per hour was recorded. The scale of this event is well captured by the Global Precipitation Measurement dataset from NASA – this is 24 hour precipitation to 14:30 UTC on 5 October 2025:-

24 hour precipitation in 14:30 on 5 October 2025 for South Asia. Data from NASA.

News reports from Nepal indicate that 47 people have been killed and more are missing. Of these fatalities, 37 are reported to have been the result of landslides in Ilam. The Kathmandu Post has started to document the events:-

“According to the District Administration Office, five people died in Suryodaya Municipality, six in Ilam Municipality, six in Sandakpur Rural Municipality, three in Mangsebung, eight in Maijogmai, eight in Deumai Municipality, and one in Phakphokthum Rural Municipality. Among the deceased are 17 men and 20 women, including eight children, the office said in its official report.”

The picture in NE India is also dire. In Darjeeling, a series of landslides have killed 23 people. These include 11 fatalities in Mirik and five in Nagrakata. Praful Rao has indicated that he will provide more detail on the landslides in Darjeeling on the Save the Hills blog in due course.

The rains have also caused extensive damage in Bhutan. At least five fatalities have been reported, mostly in “flash floods”. In this landscape, the term flash flood is usually used to describe channelised debris flows.

Of great concern is the reported situation at the Tala Hydroelectric Power Station dam on the Wangchu river in the Chukha district of Bhutan. Reports indicate that water has overflowed the structure due to a failure of the dam gates. According to Wikipedia, this dam is 92 metres tall, so a collapse would be a significant event. This is Bhutan’s largest hydropower facility, and dams are not usually designed to withstand a major overtopping event.

The situation across this region will be unclear for a while, but loyal readers will remember the late monsoon event in Nepal in 2024, in which over 200 people were killed. These events reflect changes in patterns of rainfall associated with anthropogenic climate change and changes in the pattern of vulnerability associated with poor development and construction activities. Neither are likely to improve in the next decade and beyond.

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Combined Boundary Element and Finite Volume Methods for Modeling Fluid-Induced Seismicity in Fault Networks within Low-Permeability Rocks

Geophysical Journal International - Mon, 10/06/2025 - 00:00

SummaryTo better understand the mechanics of injection-induced seismicity, we developed a two-dimensional numerical code to simulate both seismic and aseismic slip on non-planar faults and fault networks driven by fluid diffusion along permeable faults, in an impervious host rock. Our approach integrates a boundary element method to model fault slip governed by rate-and-state friction with a finite-volume method to simulate fluid diffusion along fault networks. We demonstrate the capabilities of the method with two illustrative examples: (1) fluid injection inducing slow slip on a primary rough, rate-strengthening fault, which subsequently triggers microseismicity on nearby secondary, smaller faults, and (2) fluid injection on a single fault in a network of intersecting faults, leading to fluid diffusion and reactivation of slip throughout the network. This work highlights the importance of distinguishing between mechanical and hydrological processes in the analysis of induced seismicity, providing a powerful tool for improving our understanding of fault behavior in response to fluid injection, in particular when a network of geometrically complex faults is involved.

3D joint inversion of induced polarization and self-potential data for ore body localization

Geophysical Journal International - Mon, 10/06/2025 - 00:00

SUMMARYIn mineral exploration, induced polarization and self-potential are two broadly used active and passive geophysical methods, respectively. In the case of ore bodies, both methods are associated with charge distributions associated with a secondary electrical field (induced polarization) and a source current density (self-potential). Both the chargeability and volumetric source current density distributions bring information regarding the shape of ore bodies. Therefore the joint inversion of these datasets is expected to better tomograms of ore bodies. A joint inversion approach is developed to combine both methods. The objective function to minimize includes two independent components plus a cross-gradient joint function. The use of the cross-gradient is justified from the underlying physics of the two geophysical problems at play. The structure of the cost function is tailored to overcome some problems like convergence and parameter determination in the inverse process. Two synthetic tests and a laboratory experiment are used to benchmark the proposed algorithm. We demonstrate that the joint inversion algorithm performs better than the localizations obtained from independent inversion approaches. To refine the interpretation of the shape of ores, we introduce an ore presence index using the chargeability and source current density resulting from the joint inversion algorithm. The K-Medoids clustering algorithm is used to automatically categorize the calculated ore presence index into different clusters. The cluster with larger values successfully identifies the ore bodies associated with strong chargeability and/or volumetric source current density.