Brodsky has extensively studied the physics of earthquakes.[6][7] She has investigated what causes earthquakes to trigger, as well as their
hydrogeology and
fault zone structure.[8] The impact of earthquakes on subsequent earthquakes ('triggering') is still not well understood. Brodsky demonstrated that seismic waves can trigger regional seismicity.[9] She found that dynamic stress waves from one earthquake can initiate further earthquakes.[10] She has challenged the idea that static stress controls earthquake triggering, and found that aftershocks have similar distributions as main shocks.[10][11] She showed that using the amplitude of previous earthquakes it is possible to predict
earthquake triggering at all distances.[12] By studying the
Salton Sea geothermal field, Brodsky showed that there was a relationship between human activity and seismic activity.[13] Fault slips can cause nearby rocks to fracture, changing the shape of the surface underneath them and turning the rocks on the floor into powder.
Brodsky and collaborators demonstrated that seismic waves can unclog fractures, altering the
permeability of fractured rocks.[14] Her work furthermore identified that the build-up of pressure can cause changes in
groundwater during earthquakes.[15] After
earthquakes, Brodsky has drilled deep within the
fault zone to monitor the temperature.[16] She studied the
2011 Tōhoku earthquake and tsunami, finding a series of temperature pulses that occur due to the flow of fluids through a zone of increased
permeability. Immediately after an earthquake, the fault zone can be damaged and have higher permeability, but heals within a few months.[17] Generally, earthquakes are triggered when tectonic stress overcomes friction, and Brodsky became interested in what causes this friction in the first place. Brodsky has shown that the coefficient of friction after the
2011 Tōhoku earthquake and tsunami was considerably lower than expected.[18] Alongside earthquakes, Brodsky studies
volcanoes,
geysers,
landslides and rivers.[19] Occasionally, volcanoes are triggered by distant earthquakes. Brodsky predicted that, alongside growth of bubbles and overturn of magma chambers,
volcanoes could be triggered by failure of rocks surrounding a
magma chamber.[19]