Abstract This letter compares the predictions of two expressions proposed for the porosity evolution in the context of rate and state friction. One (Segall & Rice, 1995,https://doi.org/10.1029/95jb02403) depends only on the sliding velocity; the other (Sleep, 1995,https://doi.org/10.1029/94jb03340) depends only on the state variable. Simulations of both are similar for velocity stepping and slide‐hold‐slide experiments. They differ significantly for normal effective stress jumps at constant sliding velocity. Segall and Rice (1995,https://doi.org/10.1029/95jb02403) predicts no change in the porosity; Sleep (1995,https://doi.org/10.1029/94jb03340) does. Simulation with a spring‐block model indicates that the magnitude of rapid slip events is essentially the same for the two formulations. Variations of porosity and induced pore pressure near rapid slip events are similar and consistent with experimental observations. Predicted porosity variations during slow slip intervals and the time at which rapid slip events occur are significantly different. The simulation indicates that changes in friction stress due to pore pressure changes exceed those due to rate and state effects. 
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                            Chasing Interannual Marine Paleovariability
                        
                    
    
            Abstract Several modes of tropical sea‐surface temperature (SST) variability operate on year‐to‐year (interannual) timescales and profoundly shape seasonal precipitation patterns across adjacent landmasses. Substantial uncertainty remains in addressing how SST variability will become altered under sustained greenhouse warming. Paleoceanographic estimates of changes in variability under past climatic states have emerged as a powerful method to clarify the sensitivity of interannual variability to climate forcing. Several approaches have been developed to investigate interannual SST variability within and beyond the observational period, primarily using marine calcifiers that afford subannual‐resolution sampling plans. Amongst these approaches, geochemical variations in coral skeletons are particularly attractive for their near‐monthly, continuous sampling resolution, and capacity to focus on SST anomalies after removing an annual cycle calculated over many years (represented as geochemical oscillations). Here we briefly review the paleoceanographic pursuit of interannual variability. We additionally highlight recent research documented by Ong et al., (2022,https://doi.org/10.1029/2022PA004483) who demonstrate the utility of Sr/Ca variations in capturing SST variability using a difficult‐to‐sample meandroid coral species,Colpophyllia natans, which is widespread across the Caribbean region and can be used to generate records spanning multiple centuries. 
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                            - Award ID(s):
- 2103077
- PAR ID:
- 10448251
- Publisher / Repository:
- DOI PREFIX: 10.1029
- Date Published:
- Journal Name:
- Paleoceanography and Paleoclimatology
- Volume:
- 38
- Issue:
- 8
- ISSN:
- 2572-4517
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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