Almost everything we know about this earthquake comes from one man. Stepan Krasheninnikov, a Russian explorer and naturalist, published his account in 1755 as part of his Description of Kamchatka Land. His report, based on interviews with survivors and his own observations of the transformed landscape, remains the primary source for one of the most powerful earthquakes in recorded history. Krasheninnikov described the shaking as extremely violent and lasting fifteen minutes, a duration almost unimaginable. Homes belonging to the native Itelmen were obliterated. Aftershocks continued striking even as the tsunami arrived, and they persisted into the spring of 1738, months of secondary tremors that gave the traumatized population no respite. His was the clinical eye of an Enlightenment-era scientist recording data at the edge of the known world, but the scale of devastation comes through clearly.

Krasheninnikov recorded two distinct tsunami waves. The first measured three sazhen, an old Russian unit equaling roughly 6.3 meters, enough to inundate the coast. Then came the second wave: 30 sazhen, approximately 63 meters, a wall of water that obliterated settlements and killed an unknown number of the peninsula's indigenous inhabitants. Modern seismologists have studied the 1737 event extensively, comparing it to the 1952 Severo-Kurilsk earthquake, the only other event of comparable magnitude sourced from the same subduction zone. The 1737 tsunami is thought to be at least as large as the 1952 event, and possibly larger, making it the most destructive ever generated in the Kamchatka-Kuril region. The force of the tsunami was so extreme that it stripped away dirt and sand from the Second Kuril Strait, exposing the basement rocks beneath. The ocean did not simply flood the land; it excavated it.

Perhaps the most haunting detail in Krasheninnikov's account is what happened to the landscape itself. Co-seismic deformation, the permanent shifting of the Earth's surface during the earthquake, was so drastic along the coasts that the surviving indigenous people could not locate their own settlements. This was not disorientation from trauma. The coastline had physically changed. Land that had been above water was now submerged. Beaches had vanished. Familiar landmarks were gone. The earthquake did not simply damage the human world built atop the peninsula; it rearranged the peninsula itself. For a people whose entire existence depended on knowing the coast, its fishing spots, its sheltered coves, its seasonal patterns, this geographic erasure was as catastrophic as the wave that preceded it.

The 1737 earthquake was generated by thrust faulting along the Kuril-Kamchatka Trench, where the Pacific Plate dives beneath the Okhotsk microplate at about 86 millimeters per year. This subduction zone has produced multiple magnitude 9-class earthquakes over the centuries: the 1737 event, an estimated 9.0 in 1841, and the confirmed 9.0 in 1952. The pattern is not coincidental. The geometry of the trench, the rate of convergence, and the mechanical properties of the plate boundary make this one of the most seismically active regions on Earth. Studies using tsunami data have calculated the 1737 event at a moment magnitude of 9.3, which would place it among the most powerful earthquakes in recorded human history. The Kamchatka-Kuril subduction zone does not produce moderate earthquakes and call it a century. It builds stress for generations, then releases it all at once.