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The Hawaiian Islands have many earthquakes, generally triggered by and related to volcanic activity. Seismic activity, as a result, is currently highest in the southern part of the chain. Both historical and modern earthquake databases have correlated higher magnitude earthquakes with flanks of active volcanoes, such as Mauna Loa and Kilauea. The combination of erosional forces, which cause slumping and landslides, with the pressure exerted by rising magma put a great amount of stress on the volcanic flanks. The stress is released when the slope fails, or slips, causing an earthquake. This type of seismicity is unique because the forces driving the system are not always consistent over time, since rates of volcanic activity fluctuate. Seismic hazard near active, seaward volcanic flanks is high, partially due to the especially unpredictable nature of the forces that trigger earthquakes, and partially because these events occur at relatively shallow depths. Flank earthquakes typically occur at depths ranging from 5 to 20 km, increasing the hazard to local infrastructure and communities. Earthquakes and landslides on the island chain have also been known to cause tsunamis.

Plate Movement and Deformation
Global plate motion models have determined that Iceland is rifting at a rate of approximately 18-19 mm/yr. Several processes contribute to the movement and deformation of the Icelandic landmass, such as the spreading plate boundary, active volcanism, seismic activity, and glacial activity. With time, it's believed that the result of these forces will be to create new plate boundaries, with the potential for the formation of new micro-tectonic plates.

The rate of plate rifting, or spreading, varies across the island, but generally is the greatest near zones of more active volcanism. In fact, volcanism on Iceland can be characterized by the amount of crustal spreading in each region. These distinctions reveal that regions of older, less active volcanism are split by regions of younger activity, revealing the location and trend of the active rifting zones. Most earthquakes in Iceland are recorded at or near these zones, correlated with active volcanoes and motion of the spreading boundary, often expressed as system of transform faults.

Glaciation on Iceland has a significant impact on erosional patterns, the formation of volcanic landforms, and the movement of the crust. Glacial isostatic adjustment as a response to the retreat of glacial systems since the 1890's shows a horizontal displacement of a few millimeters per year. Vertical rebound is much greater, with thinning of glaciers resulting in approximately 30 mm/yr of vertical motion. Extended periods of monitoring suggest that the rate of vertical motion of Iceland is increasing, as glaciers continue to be depleted.

Himalayan Seismicity
Just in case: https://www.nature.com/articles/s43017-021-00143-1