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Mono County got an early wakeup call on Wednesday, Aug. 24, when a magnitude-4.2 earthquake struck the area just before 5 a.m.

According to the U.S. Geological Survey, the tremblor shook parts of the Central and Eastern Sierra at 4:59:51 a.m. The epicenter was located about 9 miles southeast of Mammoth Lakes and roughly 11 miles west of Tom’s Place, at a depth of 6.1 miles.

So far, there have been no reports of serious injury or damage from the quake, which lasted about 10 seconds or so.

The Eastern Sierra joins other locations around the country that have experienced earthquake activity earlier this week. On Monday night, southern Colorado was hit by a magnitude-5.3 quake. That was followed by a similar magnitude-5.8 temblor that struck central Virginia on Tuesday afternoon. And Tuesday night, a magnitude 3.6 quake rumbled through the Bay Area.

The Mammoth quake was classified as a level IV, which is “light,” according to the USGS scale.

“Well, it finally happened, as we expected. We have 2 laboratory confirmed cases of pertussis – whooping cough – in Mammoth Lakes,” reported Mono County Health Officer Dr. Rick Johnson in a Mono Gram released Thursday afternoon.

According to Johnson’s report, one case is a 4-year old, the other an 8-year old. Johnson said both are doing well, and the families have been notified and treated appropriately. There does not appear to be any relationship between the two cases, he added.

Public Health, in cooperation with Sierra Park Pediatrics, Sierra Park Family Medicine, Mammoth Hospital Infection Control Nurse, is conducting the epidemiological investigation in order to identify close contacts. Thus far, this involves extended family in and out of the county, Swim Team, Mammoth Kids Corner, and persons at a sleepover birthday party.

According to Dr. Rick Johnson, Public Health Officer for Mono and Inyo counties, Inyo County recently diagnosed its second case of pertussis, more commonly known as whooping cough. That patient was at last report doing well, but whooping cough has emerged as a serious illness that is currently experiencing epidemic levels in California.

During the first six months of this year, 1,496 cases of pertussis were reported in California, a five-fold increase from 2009 when 258 cases were reported in the same time period.

In addition, approximately 700 possible cases of pertussis are under investigation. Six infants, all under three months of age, have died from pertussis this year. Unimmunized or incompletely immunized young infants are particularly vulnerable.

Mono County and Long Valley residents felt more shaking during the early morning hours on Thursday, due to a magnitude-3.8 earthquake that sent an early wake up call to numerous locals and visitors. The U.S. Geological Survey said Thursday morning that the quake, the second relatively substantial one within the past week, struck at 4:40 a.m. local time and was located along the Hilton Creek fault, about 10 miles east-southeast of Mammoth not far from the Green Church road area.

A similar quake last Saturday night at 11:16:26 p.m. local time, a magnitude-3.5 earthquake, woke up some area residents who had just turned in. The weekend event’s shaking only lasted 5-10 seconds, as opposed to Thursday morning’s quake, which lasted considerably longer. According the U.S.G.S., the epicenter was located approximately 10 miles east-southeast of Mammoth Lakes along the same Hilton Creek fault.

The U.S. Geological Survey classified both quakes as Type II-III, or “Weak.” No reports of injuries or damage accompanied any of the U.S.G.S. reports.

It’s unclear whether several lesser shakers (most of which went unnoticed) are entirely related to both the Saturday night and Thursday morning quakes, as numerous such small quakes are typical in this region of California. Volcanic activity accounts for minor Type I day-to-day quakes that can number in the dozens each week. U.S.G.S. technicians, however, said the two major events on Saturday and Thursday appear to be tectonic in nature, also not unusual.

“We’re not unduly concerned, but we’re keeping an eye on the activity,” said a U.S.G.S. spokesperson.

Mono County residents may have felt some shaking during the late hours of Saturday night, caused by a magnitude-3.5 earthquake that rattled the area. The shaking lasted roughly 5-10 seconds, and was classified by the U.S. Geological Survey as a Type II-III, or “Weak” quake, but it still got the attention of a few locals. At least 30 reports were called or e-mailed into the U.S.G.S. website by Sunday.

According the U.S.G.S., the epicenter was located approximately 10 miles east-southeast of Mammoth Lakes. The quake struck at 11:16:26 p.m. local time, at a depth of 7.8 kilometers or 4.8 miles.

Another smaller quake, this one a magnitude-1.2, occurred a few minutes later at 11:54:11 p.m. This one, however, was located 12 miles north of Mammoth Lakes, at a depth of 3.1 kilometers or 1.9 miles.

No reports of injuries or damage accompanied the U.S.G.S. report.

A 1.5-magnitude quake that may or may not have been an aftershock occurred at 11:59:27 a.m. on Sunday. That event, located 15 miles south-southeast of Mammoth Lakes, lasted just 3 seconds, at a depth of 6.2 kilometers or 3.9 miles.

It’s unclear whether the two smaller events were aftershocks related to the Saturday night quake, as numerous small quakes are typical in this region of California.

Residents of Lone Pine were awakened early Thursday morning — VERY early, around 3:01 a.m. — by a series of earthquakes, the largest of which was a magnitude-5.1 on the Richter Scale, that rattled that area of the Eastern Sierra.

The largest temblor was located about 18 miles southeast of Lone Pine along the east shore of the Owens River, and was followed during the next three hours by several smaller quakes ranging in magnitude between 3.0 and 3.5.
Inyo County Sheriff’s Department spokesperson Faith Felton said no damages or injuries were reported.
Quakes with magnitudes of about 5.4 have previously occurred in the area in recent years, according to U.S. Geological Survey geophysicist Randy Baldwin.
Thursday’s events were centered primarily in a rural area near Sequoia National Park. Lone Pine and its surrounding areas are located about 180 miles northeast of Los Angeles.