The USGS has confirmed a magnitude 4.5 earthquake with its epicentre 137 km NNE of Maumere, Indonesia, occurring at 11:47 UTC on Tuesday, July 21, 2026. The event's focal depth — 550.1 km — is a key factor in understanding how this earthquake was experienced at the surface.
Why Depth Matters
At a focal depth of 550.1 km, this is a deep earthquake (below 300 km), occurring well within Earth's mantle. Deep earthquakes are a distinctive feature of subduction zones where cold oceanic crust descends into the mantle. Despite the large magnitude, the extreme depth means surface shaking is distributed over a vast area and is considerably less intense at any single point than a shallow event of equivalent magnitude.
Depth is one of the most critical but least discussed parameters of any earthquake. Two earthquakes of identical magnitude can have dramatically different surface effects depending on how deep the rupture originates. Significant damage can occur to vulnerable structures — particularly unreinforced masonry, old adobe buildings, and poorly maintained older construction. Well-engineered modern buildings are designed to withstand this level of shaking with minimal structural impact, though contents may shift and non-structural elements (ceilings, partitions) can be damaged.
Magnitude 4.5: What the Science Says
On the moment magnitude scale, 4.5 represents a moderate earthquake. Moderate earthquakes are felt by virtually everyone near the epicentre. Strong shaking lasting 10–30 seconds can topple unsecured items, crack plaster, and cause poorly anchored objects to fall. Aftershocks are common following moderate events.
A magnitude 4.5 earthquake releases approximately roughly 500 tonnes of TNT of energy. For comparison, this exceeds the energy released by most conventional explosive events and is sufficient to shift tectonic stress in measurable ways across a wide region.
Tectonic Setting
Indonesia is located on the Pacific Ring of Fire at the junction of multiple major tectonic plates, including the Indo-Australian, Eurasian, and Pacific plates. With over 17,000 islands along active fault lines and subduction zones, it is among the world's most earthquake-prone nations.
This region's seismic history is an important reminder that earthquake risk is a long-term reality that requires sustained preparedness. Indonesia experiences thousands of earthquakes each year. Major events in recent decades include the 2004 Indian Ocean earthquake and tsunami (M9.1–9.3), the 2006 Yogyakarta earthquake, and the 2018 Sulawesi earthquake and tsunami. The country has invested heavily in tsunami warning infrastructure since 2004.
Practical Safety Information
Regardless of the earthquake's depth or magnitude, standard safety procedures apply. Understanding the type of building you live or work in is one of the most important steps in earthquake preparedness. Older unreinforced masonry buildings and soft-storey apartment buildings are significantly more vulnerable than modern reinforced concrete or steel-frame structures. If you have concerns, consult a structural engineer.
Agree on an out-of-area contact that family members can reach if local communications are disrupted. Identify two meeting points: one near your home and one further away. Practise earthquake drills, especially with children and elderly household members.
BMKG (Badan Meteorologi, Klimatologi, dan Geofisika) operates Indonesia's earthquake and tsunami warning system. Coastal communities should move to higher ground immediately after strong shaking without waiting for an official warning.
Track This Event
All seismic data for this event is being updated in real time as the USGS refines its measurements. Initial magnitude and depth estimates are sometimes revised as more seismograph stations report in — a process that typically completes within hours of the event. Follow updates on our live earthquake map and consider submitting a felt report if you experienced this earthquake directly.
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