Revealed that a region of Guatemala long considered low seismic risk had experienced a magnitude 7.5–7.75 earthquake, reassessing future hazard assessments.
Key Facts
- Estimated Magnitude
- 7.5 to 7.75 Mw
- Maximum Intensity
- IX (Violent) on Mercalli scale
- Depth
- 30.0 km km
- Area Affected (≥ intensity VII)
- At least 13,000 km² km²
- Deaths Reported
- At least 23
- Causative Fault
- Chixoy-Polochic Fault
By the Numbers
Location
Cause → Event → Consequence
The earthquake resulted from movement along the Chixoy-Polochic Fault, a major geological structure in Guatemala. The rupture occurred at a depth of 30 km, releasing energy consistent with a large magnitude event in a zone that planners had not widely recognized as highly seismically active.
On 22 July 1816 at 15:30 UTC, a earthquake of estimated magnitude 7.5 to 7.75 struck Guatemala, reaching a maximum perceived intensity of IX (Violent) on the Mercalli scale. The area experiencing shaking of intensity VII or greater covered at least 13,000 km², and at least 23 deaths were reported.
Discovery of this event 175 years later, through analysis of historical documents, demonstrated that portions of Guatemala previously considered low-risk were vulnerable to very large earthquakes. This finding prompted a reassessment of seismic hazard in the region and highlighted the importance of historical record research in earthquake risk planning.
Human Cost
Each dot represents approximately 10,000 deaths. Total estimated: 23 (earthquake)