Waves in lakes make waves in the Earth

Scientists at the University of Utah report that small seismic signals emanating from lakes can aid science. As a record of wave motion in a lake, they can reveal when a lake freezes over and when it thaws. And as a small, constant source of seismic energy in the surrounding earth, lake microseisms can shine a light on the geology surrounding a lake.

New study explains how continents leave their roots behind

In some areas of the seafloor, a tectonic mystery lies buried deep underground. The ocean floor contains some of the newest rock on Earth, but underneath these young oceanic plates are large swatches of much older continents that have been dislocated from their continental plates and overtaken by the younger, denser oceanic plate. Researchers have been puzzled by this phenomenon for some time: how does a continental plate leave some of itself behind?

Computer earthquake prediction in lab shows promise

By listening to the acoustic signal emitted by a laboratory-created earthquake, a computer science approach using machine learning can predict the time remaining before the fault fails. Not only does the work have potential significance to earthquake forecasting, but the approach is far-reaching, applicable to potentially all failure scenarios, including avalanches and other events.

Researchers investigate the lighter side of Earth’s inner core

Researchers report in a new study that a carbon compound called iron carbide, combined with small amounts of silicon impurities, may be an important component of the inner core. The researchers performed computer simulations to model how an iron and nickel core containing either iron carbide, or iron carbide with some silicon, compares to the density and other known characteristics of the inner core.

Recognizing seamount-forearc collisions at accretionary margins: Insights from discrete numerical simulations

We conducted discrete numerical simulations to examine the effects of seamount collisions with forearcs along actively accreting subduction margins. Modeled seamount interactions leave behind distinctive structures in overriding forearcs that differ from those found at non-accreting margins. Whereas accretion above a planar décollement produces evenly spaced thrust faults with uniform displacements, seamounts activate one or more large-offset splay faults that accommodate substantial offset. Locally oversteepened slopes develop above the seamounts, but in contrast to non-accreting margins, the steep slopes are transient. Renewed accretion following seamount passage allows the equilibrium surface slopes to recover. Seamounts also protect incoming strata in their wake, delaying formation of new thrust faults and increasing fault spacing. Weak horizons within accreting strata allow the décollement to step up above the seamount, further protecting deeper strata and vertically partitioning wedge deformation. Notably, all modeled faults form in sequence, in contrast to out-of-sequence faults found at non-accreting margins. Similar structures found at many accretionary margins, including Nankai (offshore Japan), suggest that we may underestimate the role of seamount interactions in many locations, with implications for our assessment of subduction hazards in these settings.

Xenoconformities and the stratigraphic record of paleoenvironmental change

Most interpretations of the stratigraphic record are founded on the premise that the depositional environments that produced it either have not changed appreciably through time, or else have changed very slowly. Paradoxically, some of the most important transitions in the sedimentary archive are those interpreted to reflect relatively rapid, comprehensive paleoenvironmental change. Recognition of the anomalous nature of such transitions is vital to accurately understanding their significance but is not systematically incorporated in current stratigraphic models. The new term “xenoconformity” is therefore proposed, and defined as a stratigraphic surface or gradational interval that records a fundamental, abrupt, and persistent change in sedimentary facies across basinal to global scales. Xenoconformities may mark major paleoenvironmental tipping points and signal transformations in how paleoenvironmental signals were transferred into the stratigraphic record.