In election years, ballot box success for governors also helps presidential candidates, but not the other way around

The US is not just electing a new president in 2016 – in 12 states voters will also be able to choose their next governor. In new research, Amuitz Garmendia Madariaga and H. Ege Ozen examine how presidential and gubernatorial candidates’ electoral fortunes are intertwined. They find that voters are more likely to cast a straight ticket ballots in presidential election years, and that successful gubernatorial candidates actually provide a vote boost for presidential candidates at the state level, not the other way around

Modelling the tsunami free oscillations in the Marquesas (French Polynesia)

The tsunami resonance inside basins (closed or semi-enclosed) depends on the period of the incident waves, reflection and energy dissipation, characteristics of the boundary and the geometry of the basin.When waves continuously enter the basin, they caus

Looking for two-sided coattail effects: Integrated parties and multilevel elections in the U.S.

In the context of the American federalism, integrated parties provide the necessary coordination mechanism for state and federal politicians to be electorally successful. This argument rests on the assumption that voters are able to observe the benefits of voting a straight ticket. We test this individual level explanation by using the CCES data. Moreover, at the aggregate level, we measure the so-called ‘two-sided’ coattail effects in concurrent multilevel elections in the U.S. since 1960. By using a simultaneous equation model, we estimate the reciprocal relationship between presidential and gubernatorial vote shares at the state level. While we find no consistent presidential coattails, we reveal robust and significant gubernatorial coattail effects on state-level presidential vote, underscoring the role of multilevel forces within parties in democratic federations

Frictional sliding without geometrical reflection symmetry

The dynamics of frictional interfaces play an important role in many physical systems spanning a broad range of scales. It is well-known that frictional interfaces separating two dissimilar materials couple interfacial slip and normal stress variations, a coupling that has major implications on their stability, failure mechanism and rupture directionality. In contrast, interfaces separating identical materials are traditionally assumed not to feature such a coupling due to symmetry considerations. We show, combining theory and experiments, that interfaces which separate bodies made of macroscopically identical materials, but lack geometrical reflection symmetry, generically feature such a coupling. We discuss two applications of this novel feature. First, we show that it accounts for a distinct, and previously unexplained, experimentally observed weakening effect in frictional cracks. Second, we demonstrate that it can destabilize frictional sliding which is otherwise stable. The emerging framework is expected to find applications in a broad range of systems.Comment: 14 pages, 5 figures + Supplementary Material. Minor change in the title, extended analysis in the second par

Stress Drop Variation of Deep‐Focus Earthquakes Based on Empirical Green’s Functions

We analyze source characteristics of global, deep‐focus (>350 km) earthquakes with moment magnitudes (Mw) larger than 6.0–8.2 using teleseismic P‐wave and S‐wave spectra and an empirical Green’s functions approach. We estimate the corner frequency assuming Brune’s source model and calculate stress drops assuming a circular crack model. Based on P‐wave and S‐wave spectra, the one standard deviation ranges are 3.5–369.8 and 8.2–328.9 MPa, respectively. Based on the P‐wave analysis, the median of our stress drop estimates is about a factor of 10 higher than the median stress drop of shallow earthquakes with the same magnitude estimated by Allmann and Shearer (2009, https://doi.org/10.1029/2008JB005821). This suggests that, on average, the shear stress of deep faults in the mantle transition zone is an order of magnitude higher than the shear stress of faults in the crust. The wide range of stress drops implies coexistence of multiple physical mechanisms.Plain Language SummaryThe change of shear stress (i.e., stress drop) during an earthquake is thought to be larger for deeper earthquakes than shallow earthquakes because of higher overburden pressure. However, the observational evidence for stress drop dependence on depth is still inconclusive. We estimate stress drops of earthquakes deeper than 400 km from recorded ground motion spectra. We find that the median stress drop of deep earthquakes is about one order of magnitude higher than the stress drop of shallow (<50 km) earthquakes. This implies that the shear stress of deep faults is moderately higher than of faults in the crust. The wide range of our stress drop estimates suggests that various mechanisms producing deep earthquakes coexist.Key PointsEmpiricalGreen’s functions are applied to analyze stress drops of deep‐focus earthquakesOne standard deviation ranges are 3.5–369.8 MPa for P waves and 8.2–328.9 MPa for S wavesThe median stress drops suggest that fault shear stress is an order of magnitude higher in the mantle than in the crustPeer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/154937/1/grl60493_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/154937/2/grl60493.pd

Nucleation of Laboratory Earthquakes: Quantitative Analysis and Scalings

In this study we use the precursory acoustic emission (AE) activity during the nucleation of stick-slip instability as a proxy to investigate foreshock occurrence prior to natural earthquakes. We report on three stick-slip experiments performed on cylindrical samples of Indian metagabbro under upper crustal stress conditions (30–60 MPa). AEs were continuously recorded by eight calibrated acoustic sensors during the experiments. Seismological parameters (moment magnitude, corner frequency and stress-drop) of the detected AEs (−8.8 ≤ Mw ≤ −7) follow the scaling law between moment magnitude and corner frequency that characterizes natural earthquakes. AE activity always increases toward failure and is driven by along fault slip velocity. The stacked AE foreshock sequences follow an inverse Omori type law, with a characteristic Omori time c inversely proportional to normal stress. AEs moment magnitudes increase toward failure, as manifested by a decrease in b-value from ∼1 to ∼0.5 at the end of the nucleation process. During nucleation, foreshocks migrate toward the mainshock epicenter location, and stabilize at a distance from the latter compatible with the predicted Rate-and-State nucleation size. Importantly, the nucleation characteristic timescale also scales inversely with applied normal stress and the expected nucleation size. Finally, we infer that foreshocks are the byproducts of the nucleation phase which is an almost fully aseismic process. Nevertheless, the seismic/aseismic energy release ratio continuously increases during nucleation, highlighting that, the nucleation process starts as a fully aseismic process, and evolves toward a cascading process at the onset of dynamic rupture