“Sorry, out busy, try again later.”

Posted on January 30, 2023 by Kristi Fink

“Are we having more earthquakes lately?”

Depends – how long of a timeframe does “lately” equal? A month? year? Decade? Era? Many large, powerful earthquakes have been in the news lately…. it does seem like the Earth “is busy” and we should “ask again later.” This month is not yet over, and we have already recorded several large magnitude, global events here in Spring, TX at Raspberry Shake Station R5DDF. Take a look ~ unless otherwise noted, no significant damages or human loss was incurred from these events.

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Why save the best for last (in the month)? These INTRIGUING OBSERVATIONS were made at Station R5DDF; apparently, a few polar degrees does matter to epicentral distance….take these events shown in Figures 1a and 1b – both earthquakes had the same magnitude (M7.0), occurred in the same region of the World AND had similar hypocenter depths – NOTE that one event was detected and recorded at our site location, and the other event was not. How can we explain these observations?

Figure 1a. January 08, 2023, 12:32 UTC – (Vanuatu) A magnitude M7.0 earthquake occurred in this area of the Ring of Fire. A 0.2 to 1.2 Hz BP filter has been applied to the extracted seismogram – no apparent signal is observed. The epicentral distance is approximately 104 polar degrees away from Spring, TX.

Figure 1b. January 18, 2023, 06:06 UTC – (Indonesia) The same magnitude, an M7.0, earthquake occurred in nearby Indonesia. The same 0.2 to 1.2 Hz BP filter has been applied to the extracted seismogram. The epicentral distance of this event is approximately 128 polar degrees away. How can we explain these two observations?

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Figure 2. January 09, 2023, 17:47 UTC – (Indonesia) A very powerful magnitude M7.6 earthquake occurred in Indonesia – not a new geologic experience for the region. A 0.5 Hz LP filter has been applied to the extracted seismogram.

Figure 3. January 20, 2023, 11:23 UTC – (Guadeloupe, Caribbean Sea) a large magnitude M6.2 earthquake occurred offshore this tiny island – the hypocenter was approximately 166km deep. A 0.5 Hz LP filter has been applied to the extracted seismogram.

Figure 4. January 20, 2023, 22:09 UTC – (Argentina) a very powerful magnitude M6.8 (and deep!) earthquake shook this Country. A 0.5 Hz LP filter has been applied to the extracted seismogram.

Figure 5. January 24, 2023, 18:37 UTC – (Argentina) a strong after-shock (also, deep) earthquake occurred near the main shock’s epicenter. The magnitude M6.4 event caused little to no damage because the epicenter was not nearby populous areas. A 0.8 Hz LP filter has been applied to the extracted seismogram.