Barometric Pressure METAR Code
I have been reporting barometric pressure for some time now and as well as the actual inches of mercury have been including is statement as to the pressure trend (rising, steady, falling). So far this trend statement has been subjective based on what the pressure has been the past couple of hours before the observation. Tonight I investigated METARs -- routine meteorological observations reported at the end of each hour (51 minutes after the hour) -- and found that there are actually standards for making this assessment and the gradations are much finer than what I have heretofore reported. So wherever possible I will report by the following scale.
| Rising higher than 3 hours ago | 0 | increasing then decreasing |
| 1 | increasing then steady or increasing then increasing more slowly | |
| 2 | increasing steadily or unsteadily | |
| 3 | decreasing or steady, then increasing or increasing then increasing more rapidly | |
| Steady same as three hour ago | 0 | increasing then decreasing |
| 4 | steady | |
| 5 | decreasing then increasing | |
| Falling lower than 3 hours ago | 5 | decreasing then increasing |
| 6 | decreasing then steady or decreasing then decreasing more slowly | |
| 7 | decreasing steadily or unsteadily | |
| 8 | steady or increasing then decreasing or decreasing then decreasing more rapidly |
With all of the shaking that has been and is still going on in Chile
and its movement to the east I was wondering how it might be affecting all of the big new telescopes down there.
I looked up their locations and plotted them in Google Earth along with the locations of the earthquakes greater than Richter magnitude 4.5 (automatically plotted based on a KMZ file from USGS.
Based on the strength of the initial and strongest temblor and the descriptions of the Richter scale (below) it doesn't seem like any of the scopes should have been effected by the shaking but if any of them use polar alignment, which is doubtful in this day and age, they would probably need to be realigned or otherwise adjusted. There was also an elevation change across the continent so that probably needed checking out and possibly compensating for as well.
Richter Magnitude Scale for Earthquake Severity
The Richter Scale is a measure of the energy released beneath the Earth's surface at the epicenter of the earthquake.
| Richter Magnitude | Descriptor | Probable Effects | Frequency |
|---|---|---|---|
| <2.0 | Micro | microearthquakes not felt | ~8,000/day |
| 2.0 - 2.9 | Minor | generally not felt but recorded | ~1,000/day |
| 3.0 - 3.9 | often felt but rarely cause< damage | ~49,000/year | |
| 4.0 - 4.9 | Light | Noticeable shaking of indoor items, rattling noises Significant damage unlikely | 6,200/year |
| 5.0 - 5.9 | Moderate | Can cause major damage to poorly constructed buildings over small regions. At most slight damage to well-designed buildings | 800/year |
| 6.0 - 6.9 | Strong | Can be destructive in areas up to about 160 kilometres (100 mi) across in populated areas | 120/year |
| 7.0 - 7.9 | Major | Can cause serious damage over larger areas | 18/year |
| 8.0 - 8.9 | Great | Can cause serious damage in areas several hundred miles across | 1/year |
| 9.0 - 9.9 | Devastating in areas several thousand miles across | 1/20 years | |
| 10.0+ | Epic | Never recorded | extremely rare none recorded |
| based on Wikipedia | |||
Modified Mercalli Intensity Scale
The Modified Mercalli Intensity scale measures the impact of the earthquake at the surface of the Earth.
| Category | Description | Corresponding Richter | |
|---|---|---|---|
| I. Instrumental | Not felt by many people unless in favourable conditions. | 1.0 - 3.0 | |
| II. Feeble | Felt only by a few people at best, especially on the upper floors of buildings. Delicately suspended objects may swing. | 3.0 - 3.9 | |
| III. Slight | Felt quite noticeably by people indoors, especially on the upper floors of buildings. Many do not recognize it as an earthquake. Standing motor cars may rock slightly. Vibration similar to the passing of a truck. Duration estimated. | ||
| IV. Moderate | Felt indoors by many people, outdoors by few people during the day. At night, some awakened. Dishes, windows, doors disturbed; walls make cracking sound. Sensation like heavy truck striking building. Standing motor cars rock noticeably. Dishes and windows rattle alarmingly. | 4.0 - 4.9 | |
| V. Rather Strong | Felt outside by most, may not be felt by some outside in non-favourable conditions. Dishes and windows may break and large bells will ring. Vibrations like large train passing close to house. | ||
| VI. Strong | Felt by all; many frightened and run outdoors, walk unsteadily. Windows, dishes, glassware broken; books fall off shelves; some heavy furniture moved or overturned; a few instances of fallen plaster. Damage slight. | 5.0 - 5.9 | |
| VII. Very Strong | Difficult to stand; furniture broken; damage negligible in building 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. Noticed by people driving motor cars. | 6.0 - 6.9 | |
| VIII. Destructive | Damage slight in specially designed structures; considerable in ordinary substantial buildings with partial collapse. Damage great in poorly built structures. Fall of chimneys, factory stacks, columns, monuments, walls. Heavy furniture moved. | 7.0+ | |
| IX. Ruinous | General panic; 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. | 6.0 - 6.9 | |
| X. Disastroud | Some well built wooden structures destroyed; most masonry and frame structures destroyed with foundation. Rails bent. | ||
| XI. Very Disasterous | Few, if any masonry structures remain standing. Bridges destroyed. Rails bent greatly. | ||
| XII. Catastrophic | Total damage - Everything is destroyed. Total destruction. Lines of sight and level distorted. Objects thrown into the air. The ground moves in waves or ripples. Large amounts of rock move position. | ||
| after Wikipedia | |||
Gerassimos Papadopoulos and Fumihiko Imamura Tsunami Intensity Scale
| Category | Wave Height | (a) effects on humans (b)effect on objects including boats (c) damage to buildings |
|---|---|---|
| I. Not Felt | 0 | |
| II. Scarcely Felt | 0 | (a) Felt by few people onboard small vessels. Not observed on the coast. (b) No effect. (c) No damage. |
| III. Weak | 0 | (a) Felt by most people onboard small vessels. Observed by a few people on the coast. (b) No effect. (c) No damage. |
| IV. Largely Observed | 0 | (a) Felt by all onboard small vessels and by few people onboard large vessels. Observed by most people on the coast. (b)Few small vessels move slightly onshore. (c) No damage. |
| V. Strong | 1 m | Felt by all onboard large vessels and observed by all on the coast. Few people are frightened and run to higher ground. (b) Many small vessels move strongly onshore, few of them crash into each other or overturn. Traces of sand layer are left behind on ground with favorable circumstances. Limited flooding of cultivated land. (c) Limited flooding of outdoor facilities (such as gardens) of near-shore structures. |
| VI. Slightly Damaging | 2 m | Many people are frightened and run to higher ground. (b) Most small vessels move violently onshore, crash strongly into each other, or overturn. (c) Damage and flooding in a few wooden structures. Most masonry buildings withstand. |
| VII. Damaging | 4 m | (a) Many people are frightened and try to run to higher ground. (b) Many small vessels damaged. Few large vessels oscillate violently. Objects of variable size and stability overturn and drift. Sand layer and accumulations of pebbles are left behind. Few aquaculture rafts washed away. (c) Many wooden structures damaged, few are demolished or washed away. Damage of grade 1 and flooding in a few masonry buildings. |
| VIII. Heavily Damaging | 4 m | (a) All people escape to higher ground, a few are washed away. (b) Most of the small vessels are damaged, many are washed away. Few large vessels are moved ashore or crash into each other. Big objects are drifted away. Erosion and littering of the beach. Extensive flooding. Slight damage in tsunami-control forests and stop drifts. Many aquaculture rafts washed away, few partially damaged. (c) Most wooden structures are washed away or demolished. Damage of grade 2 in a few masonry buildings. Most reinforced-concrete buildings sustain damage, in a few damage of grade 1 and flooding is observed. |
| IX. Destructive | 8 m | (a) Many people are washed away. (b) Most small vessels are destroyed or washed away. Many large vessels are moved violently ashore, few are destroyed. Extensive erosion and littering of the beach. Local ground subsidence. Partial destruction in tsunami-control forests and stop drifts. Most aquaculture rafts washed away, many partially damaged. (c) Damage of grade 3 in many masonry buildings, few reinforced-concrete buildings suffer from damage grade 2. |
| X. Very Destructive | 8 m [12 m ??] | (a) General panic. Most people are washed away. (b) Most large vessels are moved violently ashore, many are destroyed or collide with buildings. Small boulders from the sea bottom are moved inland. Cars overturned and drifted. Oil spills, fires start. Extensive ground subsidence. (c) Damage of grade 4 in many masonry buildings, few reinforced-concrete buildings suffer from damage grade 3. Artificial embankments collapse, port breakwaters damaged. |
| XI. Devastating | 16 m | (a) (b) Lifelines interrupted. Extensive fires. Water backwash drifts cars and other objects into the sea. Big boulders from sea bottom are moved inland.(c) Damage of grade 5 in many masonry buildings. Few reinforced-concrete buildings suffer from damage grade 4, many suffer from damage grade 3. |
| XII. Completely Devasating | 32 m | (a) (b) (c) Practically all masonry buildings demolished. Most reinforced-concrete buildings suffer from at least damage grade 3. |
| based on About.com: Geology | ||
