Tremor–genic slow slip regions may be deeper and warmer and may slip slower than non–tremor–genic regions

Journal Article · Thu Sep 17 00:00:00 EDT 2015 · Geochemistry, Geophysics, Geosystems

DOI:https://doi.org/10.1002/2015GC005895· OSTI ID:1221797

Montgomery-Brown, E. K. ^[1]; Syracuse, E. M. ^[2]

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1. United States Geological Survey, Menlo Park, CA (United States)
2. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

The slow slip events (SSEs) are observed worldwide and often coincide with tectonic tremor. Notable examples of SSEs lacking observed tectonic tremor, however, occur beneath Kilauea Volcano, Hawaii, the Boso Peninsula, Japan, {near San Juan Bautista on the San Andreas Fault, California, and recently in Central Ecuador. These SSEs are similar to other worldwide SSEs in many ways (e.g., size or duration), but lack the concurrent tectonic tremor observed elsewhere; instead they trigger swarms of regular earthquakes. We investigate the physical conditions that may distinguish these non-tremor-genic SSEs from those associated with tectonic tremor including: slip velocity, pressure, temperature, fluids and fault asperities, although we cannot eliminate the possibility that tectonic tremor may be obscured in highly attenuating regions. Slip velocities of SSEs at Kilauea Volcano (~10⁻⁶ m/s) and Boso Peninsula (~10⁻⁷ m/s) are among the fastest SSEs worldwide. Kilauea Volcano, the Boso Peninsula and Central Ecuador are also among the shallowest SSEs worldwide, and thus have lower confining pressures and cooler temperatures in their respective slow slip zones. {Fluids also likely contribute to tremor generation, and no corresponding zone of high v_p/v_s has been noted at Kilauea or Boso. We suggest that the relatively faster slip velocities at Kilauea Volcano and the Boso Peninsula result from specific physical conditions that may also be responsible for triggering swarms of regular earthquakes adjacent to the slow slip, while different conditions produce slower SSE velocities elsewhere and trigger tectonic tremor.

• Research Organization: Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
• Sponsoring Organization: USDOE
• Grant/Contract Number: EAR-PF-846959; AC52-06NA25396
• OSTI ID: 1221797
• Report Number(s): LA-UR-15-23280
• Journal Information: Geochemistry, Geophysics, Geosystems, Journal Name: Geochemistry, Geophysics, Geosystems; ISSN 1525-2027
• Publisher: American Geophysical Union
• Country of Publication: United States
• Language: English

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