Reading a 400,000-year record of earthquake frequency for an intraplate fault

Abstract

Our understanding of the frequency of large earthquakes at timescales longer than instrumental and historical records is based mostly on paleoseismic studies of fast-moving plate-boundary faults. Similar study of intraplate faults has been limited until now, because intraplate earthquake recurrence intervals are generally long (10s to 100s of thousands of years) relative to conventional paleoseismic records determined by trenching. Long-term variations in the earthquake recurrence intervals of intraplate faults therefore are poorly understood. Longer paleoseismic records for intraplate faults are required both to better quantify their earthquake recurrence intervals and to test competing models of earthquake frequency (e.g., time-dependent, time-independent, and clustered). We present the results of U-Th dating of calcite veins in the Loma Blanca normal fault zone, Rio Grande rift, New Mexico, United States, that constrain earthquake recurrence intervals over much of the past ∼550 ka-the longest direct record of seismic frequency documented for any fault to date. The 13 distinct seismic events delineated by this effort demonstrate that for >400 ka, the Loma Blanca fault produced periodic large earthquakes, consistent with a time-dependent model of earthquake recurrence. However, this time-dependent series was interrupted by a cluster of earthquakes at ∼430 ka. The carbon isotope composition of calcite formed during this seismic cluster records rapid degassing of CO 2 , suggesting an interval of anomalous fluid source. In concert with U-Th dates recording decreased recurrence intervals, we infer seismicity during this interval records faultvalve behavior. These data provide insight into the long-term seismic behavior of the Loma Blanca fault and, by inference, other intraplate faults.earthquake | fault | geochronology | seismic | hazard R ecent increases in the rate of seismicity associated with subsurface wastewater injection have generated substantial interest in the seismic cycles of intraplate faults (1-4). Unfortunately, increasing seismicity in the continental interior has outpaced our understanding of the processes that govern natural earthquake recurrence on these faults. The seismic cycles of plate boundary faults are much better known, although the exact nature of their earthquake recurrence distributions remains much debated (5, 6). At the heart of this debate lies a fundamental question: Are seismogenic faults ever controlled by a stress-renewal process that can be approximated by elastic rebound theory? The latter states that stress buildup will be accommodated elastically until shear stress on the fault reaches a threshold value that will allow failure.If seismogenic faults are governed by a renewal process, then elastic rebound theory predicts that earthquakes will be produced quasiperiodically (7) (i.e., occur at regular intervals and therefore be "time-dependent") with steady tectonic loading. However, an alternative view posits that spatial and temporal variations in fault strength and/or mechan...

Are U‐Th Dates Correlated With Historical Records of Earthquakes? Constraints From Coseismic Carbonate Veins Within the North Anatolian Fault Zone

“…Eventually, as listed in the following, there might be some important challenges of using this method solely as a paleoseismological technique: Since the carbonate bands may not be uniform along the entire fracture (Brogi & Capezzuoli, ), one crosscut of a vein could be insufficient for reconstructing the whole paleoseismic history of an area. Even if the fluid discharge and related carbonate precipitation start simultaneously with the earthquake (Brogi & Capezzuoli, ; Montgomery & Manga, ; Muir‐wood & King, ), the time it takes a coseismic band to reach its maximum thickness depends on several variables (Altunel & Karabacak, ; Karabacak et al, ; Mesci et al, ). Therefore, it is important that dating should be performed from the closest section of each band to the fracture wall (i.e., the plane where the precipitation first starts; Williams et al, ; Capezzuoli et al, ). Although each alternate band in a vein is in close relation with repeated fault reactivation, each vein may not record all seismic releases around the region. First, for a good coseismic carbonate record to be created the earthquake must have an intensity (I > VI, like our 1430 AD peak) to allow the opening of the planar fracture and second, have a close epicenter ( d < 200 km, unlike 1668 AD and 1939 AD events) that will allow permeability enhancement (Parvin et al, ; Shi et al, ). …”

Recurrence Interval Analysis on Electricity Consumption of an Office Building in China

“…Therefore, RIA enables us to analyze the profile of volatility in different magnitudes, and it does not have to make the presumption that the load between past and future should follow specific functional relationships [23]. Owing to its wide application, RIA is now used in diverse fields, including the study of climate [24], earthquake activities [25], heartbeat monitoring [26], and financial volatility [27].…”

A New Perspective on Improving Hospital Energy Administration Based on Recurrence Interval Analysis

“…Based on the extreme event that has happened at a specific time, this method can estimate the recurrence probability of next one. This method has been proved efficient in forecasting nature hazards and financial market volatilities [20][21][22]. In practice, by analyzing the characteristics of the recurrence intervals of extreme power fluctuations, our study can help the energy administrator to forecast the hospital power system risk, both in probability and magnitude.…”

“…So far, this RIA method has proved to be effective in forecasting natural hazards, financial market volatility, and electricity consumption features in units of enterprise and office building [11,[20][21][22][23]. Also, the introduction of high-frequent data is able to reflect the instantaneous fluctuation of power consumption, which does count for much more in hospital energy administration than daily data.…”