Last week’s twin major earthquakes caused only minor injuries near the epicenter in Ridgecrest, Calif.
But about 95 miles northeast of the epicenter, authorities are investigating whether one of the quakes caused the death of a man found under a vehicle in Pahrump, Nev.
What do we know about the death?
Deputies with the Nye County Sheriff’s Office found the 56-year-old man Tuesday beneath the Jeep in Pahrump, a town on the California-Nevada border about 95 miles northeast of the epicenter area near Ridgecrest.
Sgt. Adam Tippetts said in a news release that the man was last seen alive July 3 at a local gas station.
His name has been withheld, pending notification of next of kin.
What do we know about the intensity of the quakes?
The worst shaking — “violent,” or intensity level 9 on the Modified Mercalli Intensity Scale — was limited to a geographically small and unpopulated region in the Mojave Desert during Friday’s quake.
“Severe,” or intensity level 8, shaking was felt in Ridgecrest, population 29,000. That was worse shaking than what was felt on Independence Day.
The highest-populated areas of California on Friday night felt only “weak” or “light” shaking of intensity level 4 or less, including Los Angeles and San Francisco, as well as Nevada.
The question is whether the shaking was strong enough to cause the accident in Pahrump.
Here is a USGS explanation of quake intensity levels.
Intensity 10: Extreme — some well-built wooden structures destroyed; most masonry and frame structures destroyed with foundations. Rails bent.
Intensity 9: Violent — damage considerable in specially designed structures; well-designed frame structures thrown out of plumb. Damage great in substantial buildings, with partial collapse. Buildings shifted off foundations.
Intensity 8: Severe — damage slight in specially designed structures; considerable damage in ordinary substantial buildings with partial collapse. Damage great in poorly built structures. Fall of chimneys, factory stacks, columns, monuments, walls. Heavy furniture overturned.
Intensity 7: Very strong — damage negligible in buildings of good design and construction; slight to moderate in well-built ordinary structures; considerable damage in poorly built or badly designed structures; some chimneys broken.
Intensity 6: Strong — felt by all, many frightened. Some heavy furniture moved; a few instances of fallen plaster. Damage slight.
Intensity 5: Moderate — felt by nearly everyone; many awakened. Some dishes, windows broken. Unstable objects overturned. Pendulum clocks may stop.
Intensity 4: Light — felt indoors by many, outdoors by few during the day. At night, some awakened. Dishes, windows, doors disturbed; walls make cracking sound. Sensation like heavy truck striking building. Standing cars rocked noticeably.
Intensity 3: Weak — felt quite noticeably by people indoors, especially on upper floors of buildings. Many people do not recognize it as an earthquake. Standing cars may rock slightly. Vibrations similar to the passing of a truck. Duration estimated.
Intensity 2: Weak — felt only by a few people at rest, especially on upper floors of buildings.
Intensity 1: Not felt — not felt except by a very few under especially favorable conditions.
The magnitude 7.1 earthquake started at an epicenter 10 miles northeast of central Ridgecrest. But it occurred on a fault that focused the worst shaking waves away from Ridgecrest and Trona, to the northwest and southeast, respectively, and into sparsely populated areas, Caltech seismologist Egill Hauksson said.
Where do we stand with aftershocks?
Aftershocks from the recent quakes near Ridgecrest are decreasing in both frequency and magnitude, and seismologists say they expect the pattern to continue.
The earthquakes on July 4 and 5 were the strongest to hit the area in 20 years. Thousands of aftershocks have already been reported, and scientists have said they expect thousands more — about 34,000 over the next six months.
But since an initial cluster of magnitude 5 and above quakes that struck in the hours following the 7.1 temblor, the aftershocks have been subsiding in intensity and striking less often, an analysis of seismological data shows.
Hauksson said late Monday the earthquake sequence seemed to be quieting more quickly than initially anticipated.