Relationship Between Dike Injection and <i>b</i> ?Value for Volcanic Earthquake Swarms

Dike swarms are the fossil remains of regions crust that have undergone repeated magma injections. Volcanic earthquake and geodetic measurements are, at least in part, a record active injection fluids (water, gas, or magma) into fractures. Here, we link these two ways observing magmatic systems by noting dike thicknesses magnitudes share similar scaling parameters. In Jurassic Independence swarm eastern California median thickness is ?1 m, to other worldwide, but glacially polished exposures reveal typical comprises number dikelets lognormally distributed with mean ?0.1 m. Assuming dikes fill penny-shaped cracks given aspect ratio, moment magnitude diking event can be estimated. A Monte Carlo simulation dike-induced earthquakes based on observed variations yields frequency-magnitude distribution remarkably like volcanic swarms, b-value ?1.7. We suggest composed dikelets, as well plutons built incrementally sheet intrusions, physical complements seismic some palpable expression incremental emplacement.