4.3
magnitude
3.1
magnitude
3.6
magnitude
3.6
magnitude
3.3
magnitude
3.6
magnitude
3.4
magnitude
3.4
magnitude
3.2
magnitude
3.5
magnitude
4.0
magnitude
5.0
magnitude
5.0
magnitude
3.6
magnitude
3.1
magnitude
3.2
magnitude
3.3
magnitude
3.0
magnitude
3.1
magnitude
5.3
magnitude
3.9
magnitude
3.1
magnitude
4.1
magnitude
4.2
magnitude
3.8
magnitude
3.3
magnitude
3.3
magnitude
3.3
magnitude
3.0
magnitude
3.0
magnitude
advertisement
The Quake Tracker displays quakes from the past 30 days with magnitudes above 3.0 in Northern California, 4.0 in Southern California, 5.0 in the United States, and 7.0 in North America. Quakes below magnitude 3.0 are often not felt and do not appear on this map.
Intensity contours show how strongly a quake was felt and are displayed on the Quake Tracker when available. Rather than a gauge of pure shaking, intensity takes into account the effects on people and damage to infrastructure. The measure is designated using Roman numerals.
A quake at intensity III can be felt near the epicenter, but with no damage to structures. An intensity VII quake is widely felt and can destroy poorly built structures. At intensity VIII and beyond, structural engineers help determine how to categorize the quake based on observable damage, which can include rails bent, bridges destroyed and buildings shifted off their foundations.
Our optional fault layer shows fault lines from the USGS that cross the Bay Area that have seen evidence of seismic activity in the last 150 years. These faults are considered “active” and are likely to cause another earthquake.
All data in this project comes from the U.S. Geological Survey. Visit the agency’s site to opt into its Earthquake Notification Service.
Design & Development
Evan Wagstaff • evan.wagstaff@sfchronicle.com • @ evanwagstaff
Hilary Fung • hilary.fung@sfchronicle.com • @ hil_fung